Hindawi Publishing CorporationJournal of Analytical Methods in ChemistryVolume 2013 Article ID 803767 8 pageshttpdxdoiorg1011552013803767
Research ArticleThe Use of 771015840881015840-Tetracyanoquinodimethane for theSpectrophotometric Determination of Some Primary AminesApplication to Real Water Samples
Theiarsquoa N Al-Sabha and Najwa M Al-Karemy
Chemistry Department College of Education Mosul University Mosul 00964 Iraq
Correspondence should be addressed toTheiarsquoa N Al-Sabha dr theiaayahoocouk
Received 2 May 2013 Revised 15 August 2013 Accepted 20 August 2013
Academic Editor Antonio Ruiz Medina
Copyright copy 2013 T N Al-Sabha and N M Al-Karemy This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited
A sensitive simple and accurate spectrophotometric method was developed for the quantitative determination of some primaryaliphatic and aromatic amines that is ethylamine 12-diaminopropane aniline p-aminophenol and benzidine The method isbased on the interaction of these amines in aqueous medium with 771015840881015840-tetracyanoquinodimethane (TCNQ) reagent in thepresence of a buffer solution and surfactant (in the case of aromatic amines) to form charge-transfer complexes measurable atmaximumwavelengths ranging between 323 and 511 nm Beerrsquos law is obeyed over the concentration ranges of 0025 and 30120583gmLand the molar absorptivity is ranged between 8977 times 103 and 58034 times 104 Lsdotmolminus1sdotcmminus1 for these aminesThemethod was appliedfor the determination of benzidine in the river sea and tap waters The TCNQ complexes with the previously mentioned amineswere formed in the ratio of 1 1 amine TCNQ and their stability constants ranged between 878 times 104 and 1844 times 105 Lsdotmolminus1
1 Introduction
A great number of aromatic amines are of considerableimportance in industrial toxicological and pharmaceuticalaspects [1] Short-chain aliphatic amines are presented widelyin the aquatic environment due to their widespread use inseveral industrial chemical and manufacturing applications[2 3] Also these amines are common components of biologi-cal systems as degradation products of organicmaterials suchas amino acids and proteins In addition to hygienic problemsdue to stinging smell these compounds may be hazardousto human health as they are sensitizers and irritants to skineyes mucus membranes and respiratory tract Also they canreact with certain nitrogen-containing compounds to formnitrosamines which are potentially carcinogenic substances[4]
The charge-transfer (CT) reactions had been widelystudied spectrophotometrically in the determination ofaliphatic and aromatic amines that are easy to be determined
based on CT complex formation with some electron 120587-acceptors such as chloranil [5ndash7] 23-dichloro-56-dicyano-14-benzoquinone (DDQ) [8] fluoranil [9] dinitroben-zene [10] 1-fluro-24-dinitrobenzene [11] and 1-chloro-24-dinitrobenzene [12] Most of the previous methods sufferfrom the lack of sensitivity and selectivity and the estima-tion of these compounds is applied in organic medium7788-Tetracyanoquinodimethane (TCNQ) is strong elec-tron acceptor and applied in the determination of severalelectron donor drugs containing primary secondary ortertiary amino group and the review of the literature inthe last decade had been mainly concentrated on the CT-complexes spectral studies [13ndash18]
The present research aims chiefly to develop a sensi-tive selective simple and quick spectrophotometric methodfor the determination of samples of primary aliphatic andaromatic amines namely ethylamine 12-diaminopropaneaniline p-aminophenol and benzidine in aqueous solutionwith TCNQ reagent by measuring the absorbance at 120582max
2 Journal of Analytical Methods in Chemistry
of new charge-transfer absorption band and without anyderivatization or catalysis In addition to applying themethodfor determination of benzidine in various water samples
2 Experimental
21 Apparatus All absorption measurements were madeon a Shimadzu UV-210A double-beam spectrophotometersupplied with a digital printer DP80Z and matched 1 cmoptical silica cells
22 Reagents All reagents used were of analytical grade andobtained from Fluka and BDH companies
(1) TCNQ solution (1 times 10minus3M) is prepared freshly bydissolving 00102 g of 771015840881015840-tetracyanoquinodime-thane in absolute acetone or acetonitrile solventfor determination of aromatic or aliphatic aminesrespectively and diluted to the mark in 50mL volu-metric flask with the same solvent
(2) Standard solutions of primary aliphatic and aro-matic amines (100 120583gmL) are prepared individuallyby dissolving 001 g of pure amine(ethylamine 12-diaminopropane aniline m-aminophenol and ben-zidine) in 5mL ethanol and diluted to the markwith distilled water in 100mL volumetric flask Thesesolutions were further diluted with water to requiredconcentrations for working solutions
(3) Phosphate buffer solutions of pH values 602 986and 1065 were prepared by mixing various volumesof 02M potassium dihydrogen orthophosphate solu-tion with 02M potassium hydroxide solution andadjusted with pH meter type Philips (PW9420)
(4) Cetylpyridinium chloride (CPC) and cityltrimethy-lammonium bromide (CTAB) surfactants were pre-pared in 01 concentration by dissolving 01 g inwarm distilled water and the volume was completedto 100mL in calibrated flask
3 General Procedures
31 Determination of Primary Aliphatic Amines Aliquots ofstandard primary amine solutions of ethylamine and 12-diaminopropane were transferred separately into a series of10mL calibrated flasks To each of these were added 05 and10mL of 1 times 10minus3M TCNQ and the solutions were heatedat 40 and 50∘C for 20 and 30min for ethylamine and 12-diaminopropane respectively then the solutions were cooledto room temperature and diluted to the mark with distilledwater The absorbances of the complexes were measured at464 and 470 nm for the previous amines respectively againstcorresponding reagent blank
32 Determination of Primary Aromatic Amines Aliquots ofstandard primary amine solutions of aniline p-aminophenoland benzidine were transferred separately into a series of10mL calibrated flasks To each of these were added the opti-mum amounts of TCNQ phosphate buffer solution andCPC
01
310 350 390 430 470 510 550 590 630 670 710 750
290 310 330 350 370
02
03
04
05
06
07
Abso
rban
ce
(a)
(b)
(c)
Wavelength (nm) for (b) and (c)
Wavelength (nm) for (a)
Figure 1 Absorption spectra for the complexes of 05mL of1 times 10minus3M TCNQ with (a) 2120583gmL aniline (b) 2 120583gmL p-aminophenol and (c) 075 120583gmL benzidine versus blank reagent
660420 900820740500 580
01
02
03
05
04
Abso
rban
ce
Wavelength (nm )
(a)
(b)
Figure 2 Absorption spectra for the complexes of 05mL of 1 times10minus3M TCNQ and (a) 1 120583gmL ethylamine and (b) 2120583gmL 12-diaminopropane versus blank
(or CTAB in the case of benzidine) according to the orderof addition as listed in Table 3 The solutions were dilutedto the mark with distilled water and the absorbances of thecomplexes were measured at room temperature immediately(in the case of p-aminophenol the solutions were heated at40∘C for 5min and cooled to room temperature then dilutedto the mark with distilled water) at 323 511 and 500 nm foraniline p-aminophenol and benzidine respectively
4 Results and Discussion
41 Absorption Spectrum of the CT Complexes Primary aro-matic and aliphatic amines react with TCNQ in the presenceof phosphate buffer solution (in the case of aromatic amines)to give a red coloured complexes with maximum absorptionspectra at 511 500 464 and 470 nm for p-aminophenolbenzidine ethylamine and 12-diaminopropane respectivelywhereas aniline gave a yellow coloured complex at 323 nm(Figures 1 and 2) and their reagent blanks gave maximumabsorption at 320 nm for p-aminophenol and benzidine
Journal of Analytical Methods in Chemistry 3
whereas they gave it at 395 nm for aniline and 832 nm forethylamine and 12-diaminopropane under their optimumconditions
42 Effect of Solvent Different solvents such as acetonitrileacetone ethanol methanol dioxane and water were testedas reactionmedia for interaction between amines and TCNQ120587-acceptor It was found that TCNQ reagent reacted withprimary secondary and tertiary aliphatic and aromaticamines in the medium of previous solvents and produceddifferent colours but using water as a solvent for amines andacetonitrile or acetone for TCNQ and dilution with waterselective reactions between TCNQ and primary aliphatic andaromatic amines occurred and forming coloured 119899-120587 charge-transfer complexeswithmaximumabsorption at wavelengthsranged between 323 and 511 nm for given amines whereasother amines were either unreacted or gave low absorptionresponse Therefore this system of solvents is recommendedin our method
43 Effect of pH and Buffer Solutions The effect of pH onthe absorption of the complexes produced by the reactionof TCNQ with primary amines was studied using differentpHs ranging from 2 to 12 It was found that these complexesare formed in the final pH of 986 602 and 1065 for p-aminophenol aniline and benzidine respectively by addi-tion of NaOH solution and decreases in absorbances werefound through addition of HCl which may be attributedto the liberation of hydrogen cyanide whereas it was foundthat the absorbances of aliphatic amines were decreasedthrough addition of NaOH or HCl and the final pHs oftheir reaction solutions were 720 and 662 for ethylamineand 12-diaminopropane respectively Different buffers of thesame pHvalues as mentioned before were prepared by usingcarbonate borate phosphate ammonia and citrate buffers toinvestigate the sensitivity of the amine-TCNQ complexes Itwas found that phosphate buffer solution (KH
2PO4+ KOH)
increased the sensitivity for the aromatic amine-TCNQcomplexes (Table 1) and caused a bathochromic shift for p-aminophenol (460 997888rarr 475 nm) whereas the absorbances ofaliphatic amine-TCNQ complexes were decreased Howeverthe amounts of phosphate buffer solution at fixed pH valuesas cited before for aromatic amines were studied and foundto be 05 10 and 08mL which are the optimum amountsfor aniline p-aminophenol and benzidine respectively andwhich are recommended in the subsequent experiments
44 Effect of Reaction Time and Temperature The reactiontime was determined by following the color development atroom temperature (28∘C) and in thermostatically controlledwater bath at different temperatures up to 50 plusmn 1∘C Theabsorbance was measured at 5- and 10-minute intervalsagainst reagent blank treated similarly It was observedthat the absorbance reached maximum after addition ofthe reagent solution immediately at room temperature foraniline and benzidine after 5min at 40∘C for p-aminophenoland after 20 and 30min at 40 and 50∘C for ethylamineand 12-diaminopropane respectively and the stability of
Table 1 Effect of buffer solutions on the absorbance of aromaticamine-TCNQ complexes
Type of buffer solutionAbsorbance of TCNQ complex with
mdash mdash 0216lowastAbsorbance at 460 nmlowastlowastAbsorbance at 475 nm
their absorbances was achieved after cooling to the roomtemperature (Table 3)These temperatures and reaction timeswere chosen for colour development
45 Effect of TCNQ Concentration The effect of changingthe TCNQ concentration (02ndash20mL of 1 times 10minus3M) on theabsorbance of solution containing a fixed amount of eachprimary amine (10120583gmLminus1) was studied It is evident that theabsorbance increases with increasing TCNQ concentrationand reached maximum on using 05mL of 1 times 10minus3MTCNQ for aniline p-aminophenol benzidine and 12-diaminopropane and 10mL for ethylamine (Table 3)There-fore these concentrations were used in all subsequent work
46 Effect of Surfactant Effect of various surfactants includ-ing CTAB CPC tween-80 and triton x-100 of 01 concen-tration was tested It was found that the cationic surfactantsCPC and CATB caused a bathochromic shift with increasingin the sensitivity for aromatic amines (Table 2) while itdecreased the sensitivity of aliphatic amines However 05ndash30mL of 01 CPC were tested on the absorption of 25and 15 120583gmLminus1 aniline and p-aminophenol respectively and02ndash20mL of 01 CTAB on the absorption of 10 120583gmLminus1benzidine in the presence of phosphate buffer solution It wasfound that 05mL of CPC is the optimum amount for anilineand p-aminophenol and 1mL of CTAB for benzidine whichis recommended in subsequent experiments
47 Effect of Order of Addition In order to obtain the highcolour intensity the order of addition of reagents for aromaticamines should be followed as given in the Table 3 otherwisea loss in colour intensity was observed
However the optimum reaction conditions for develop-ing the colour intensity of primary amine-TCNQ complexesare summarized in Table 3
4 Journal of Analytical Methods in Chemistry
Table 2 Effect of surfactants on the absorption of aromatic amine-TCNQ complexes
Under the experimental conditions described in Table 3standard calibration curves of CT complexes for aliphatic andaromatic amines with TCNQ were constructed by plottingabsorbance versus concentrationThe correlation coefficientsranged from 09961 to 09993 indicating good linearityBeerrsquos law is obeyed in the ranges cited in Table 4 and themolar absorptivity values indicate the high sensitivity of themethod
6 Precision and Accuracy
Six replicate measurements are performed at three differentconcentrations of each amineThe relative standard deviationand recovery results indicated the high precision andaccuracy of the proposed method (Table 5)
7 Interferences
The interference from various organic nitrogen compoundsincluding secondary tertiary amines and amides in addition
to sodium chloride n-hexane and glucose on the deter-mination of 1 120583gmL of p-aminophenol (as an example forprimary aromatic amines) and 05120583gmL of ethylamine (asan example for primary aliphatic amines) was examined Itwas found that these compounds did not affect the recoveryin the range from 5 120583gmL of triethylamine to 2500120583gmL ofacrylamide for ethylamine and from 5 120583gmL of diethylamineto 100 120583gmL of acetanilide for p-aminophenol The resultsare summarized in Table 6
8 Application to Real Water Samples
The described method was applied to the analysis of ben-zidine in tap river and sea waters Three different concen-trations 25 50 and 10 120583gmL of benzidine were added tothe various filtered volumes of tap Dijlla river and syntheticsea waters [20] in final volume of 10mL and treated asdescribed in the previous general procedure The results inTable 7 indicated that benzidine could be determined in thepresence of small volumes of tap and river waters but aninterference was observed in the presence of small volumes
Journal of Analytical Methods in Chemistry 5
Table 5 Precision and accuracy data for primary amines determi-nation obtained by the proposed method
of sea water this may be attributed to the formation of metal-ligand complexes
9 Stoichiometry
The stoichiometry of the reaction of primary amines withTCNQ was studied by Jobrsquos method [21] using solutionsof equimolar (1 times 10minus3M) of each primary aliphatic andaromatic amines and TCNQ reagent (1 times 10minus4M in the caseof benzidine) The results obtained in Figure 3 show that 1 1amine to reagent was formed This indicates that only oneamino group is responsible for the formation of the products
10 Stability Constant ofAmine-TCNQ Complexes
The apparent stability constant was estimated by compar-ing the absorbance of a solution containing stoichiometricamounts of the primary amine and TCNQ (As) to onecontaining an excessive (optimum) amount of TCNQ reagent(Am) The average conditional stability constants of thecomplexes are calculated by the following equation
Kc = 1 minus 1205721205722119862
120572 = Am minus AsAm
(1)
where Kc is the association constant (Lsdotmolminus1) 120572 the dissoci-ation degree and 119862 the concentration of the complex whichis equal to the concentration of primary amine The resultsshown in Table 8 indicate that the complexes are relativelystable
11 Reaction Mechanism
The nature of the reaction between primary amines in aque-ous solution and TCNQ reagent is not clearly understoodMost of the spectrophotometric methods with TCNQ [22ndash26] are based on the charge-transfer interaction of radicalanion TCNQminus with the radical cation donors (D+) formed inacetonitrile medium leading to enhancement of the absorp-tion bands of TCNQ reagent in acetonitrile solvent at 840825 762 and 742 nm However in the present work it wasobserved that the complexes are formed in aqueous mediumin the ratio of 1 1 amine TCNQ with the appearance of anew absorption bands at 464 470 323 511 and 500 nmfor ethylamine 12-diaminopropane aniline p-aminophenoland benzidine respectively which is not shown by either ofthe components present in solution which may be attributedto the complete transfer of the unshared pair of electronson the nitrogen atom to TCNQ reagent and assigned as acharge-transfer complex absorption bands On this basis atentative reactionmechanismhas been proposed and given inScheme 1
12 Comparison with Other ReportedSpectrophotometric Methods
A comparison of some parameters linearity range andsensitivity of the current method with those of some otherreported spectrophotometric methods using different 120587-acceptors was described (Table 9) It is quite clear thatcurrent method is more sensitive than the reported methodsand all the charge-transfer complexes of TCNQ reagenthaving maximum absorption at visible regions except ofTCNQ-aniline complex appears at UV region
13 Conclusion
The proposed method is simple rapid sensitive and eco-nomical compared to already reported methods and does
6 Journal of Analytical Methods in Chemistry
Table 7 Determination of benzidine in different waters
Water Benzidine added (120583gmL) Recovery of benzidine found per mL of water005 01 03 05 10 15
not require any pretreatment of the primary amines orextraction procedure and has a good accuracy and precisionOn the other hand in terms of simplicity and expense themethod could be considered superior in comparison with thepreviously reported methods especially with those based onnonaqueous medium
References
[1] Kirk-Othmer Encyclopedia of Chemical Technology John Wileyamp Sons New York NY USA 3rd edition 1979
[2] E Psillakis andN Kalogerakis ldquoApplication of solventmicroex-traction to the analysis of nitroaromatic explosives in watersamplesrdquo Journal of Chromatography A vol 907 no 1-2 pp 211ndash219 2001
[3] R Belloli B Barletta E Bolzacchini S Meinardi M Orlandiand B Rindone ldquoDetermination of toxic nitrophenols inthe atmosphere by high-performance liquid chromatographyrdquoJournal of ChromatographyA vol 846 no 1-2 pp 277ndash281 1999
[4] J Namiesnik A Jastrzebska and B Zygmust ldquoDeterminationof volatile aliphatic amines in air by solid-phase microextrac-tion coupled with gas chromatography with flame ionizationdetectionrdquo Journal of Chromatography A vol 1016 no 1 pp 1ndash92003
[5] P C Dwivedi andA K Banga ldquoInteraction of primary aliphaticamines with chloranil Kinetic and spectroscopic studiesrdquoJournal of Physical Chemistry vol 85 no 12 pp 1768ndash1769 1981
[6] R E Smith and W R Davis ldquoSpectrophotometric determina-tion of amines with p-chloranilrdquo Analytical Chemistry vol 56no 13 pp 2345ndash2349 1984
[7] T N Al-Sabha Spectrophotometric micro determination of someorganic nitrogen compounds (amines and aldoximes) and theirbinary mixtures with chloranil [MS thesis] Mosul UniversityMosul Iraq 1984
[8] T N Al-Sabha The use of chargendashtransfer complex in selectivespectrophotometric determination of amines and application topharmaceutical preparations [PhD thesis] Mosul UniversityMosul Iraq 1997
8 Journal of Analytical Methods in Chemistry
[9] G K Hanna Application of charge transfer technique in traceanalysis [MS thesis] Mosul University Mosul Iraq 1986
[10] J O Singh J D Anunziata D Jorge and J J Silber ldquon-120587electron donor-acceptor complexes II Aliphatic amines withdinitrobenzenesrdquo Canadian Journal of Chemistry vol 63 no 4pp 903ndash907 1985
[11] L Forlani E Marianucci and P E Todesco ldquoCatalysis in nucle-ophilic aromatic substitution reactions Kinetic behaviour of 2-hydroxypyridine and related compounds in reaction between1-fluoro24-dinitrobenzene and aminesrdquo Gazzetta Chimica Ital-iana vol 122 p 9349 1992
[12] L Forlani ldquoCatalysis in nucleophilic aromatic substitutionreactionsThe presence of molecular complexes on the pathwayof reactions between 1-fluoro- and 1-chloro-24-dinitrobenzeneand aliphatic aminesrdquo Journal of the Chemical Society vol 8 pp1525ndash1530 1993
[13] R S Bakry A F M El Walily and S F Belal ldquoSpectropho-tometric determination of some phenolic sympathomimeticdrugs through reaction with 26-dihaloquinone chlorimidesrdquoMikrochimica Acta vol 127 no 1-2 pp 89ndash93 1997
[14] A S Amin G O El-Sayed and Y M Issa ldquoUtility of certain120587-acceptors for the spectrophotometric determination of nor-floxacinrdquo Analyst vol 120 no 4 pp 1189ndash1193 1995
[15] C S P Sastry K R Rao and D S Prasad ldquoDetermination ofcefadroxil by three simple spectrophotometric methods usingoxidative coupling reactionsrdquo Microchimica Acta vol 126 no1-2 pp 167ndash172 1997
[16] F A Aly F Belal and M I Walash ldquoColorimetric determina-tion of prenalterol hydrochloride in dosage formsrdquo Journal ofPharmaceutical and Biomedical Analysis vol 12 no 7 pp 955ndash958 1994
[17] F L Zhao B Z Xu Z Q Zhang and S Y Tong ldquoStudy onthe charge-transfer reaction between 7788-tetracyanoquinodi-methane and drugsrdquo Journal of Pharmaceutical and BiomedicalAnalysis vol 21 no 2 pp 355ndash360 1999
[18] C S P Sastry B S Sastry J V Rao and R R Krishna ldquoSpec-trophotometric methods for the determination of tolnaftaterdquoTalanta vol 40 no 4 pp 571ndash576 1993
[19] T N Al-Sabha and O A Al-Taee ldquoSpectrophotometric deter-mination of p-aminophenol and m-aminophenol in theiradmixture using tetracyanoethylene in aqueous mediumrdquo Jour-nal of National Chemistry vol 28 pp 572ndash584 2007
[20] A Henriksen ldquoAn automatic method for determining nitrateand nitrite in fresh and saline watersrdquo The Analyst vol 90 no1067 pp 83ndash88 1965
[21] P Job Spectrochemical Methods of Analysis Wiley IntersienceNew York NY USA 1971
[22] A Taha andG Rucker ldquoUtility of pi-acceptors in alkaloid assayrdquoArchiv Der Pharmazie vol 310 pp 485ndash494 1977
[23] H F Askal G A Saleh and N M Omar ldquoUtility of certain120587-acceptors for the spectrophotometric determination of somepenicillinsrdquo Analyst vol 116 no 4 pp 387ndash390 1991
[24] M M Abdel-Khalek M E Abdel-Hamid and M S MahrousldquoUse of 7788-tetracyanoquinodimethane in the colorimetricdetermination of some antihistaminesrdquo Journal of the Associa-tion of Official Analytical Chemists vol 68 no 5 pp 1057ndash10591985
[25] H Salem ldquoSpectrophotometric determination of 120573-adrenergicblocking agents in pharmaceutical formulationsrdquo Journal ofPharmaceutical and Biomedical Analysis vol 29 no 3 pp 527ndash538 2002
[26] G G Mohamed S M Khalil M A Zayed and M A E-HEl-Shall ldquo26-Dichloroquinone chlorimide and 7788-tetracy-anoquinodimethane reagents for the spectrophotometric deter-mination of salbutamol in pure and dosage formsrdquo Journal ofPharmaceutical and Biomedical Analysis vol 28 no 6 pp 1127ndash1133 2002
of new charge-transfer absorption band and without anyderivatization or catalysis In addition to applying themethodfor determination of benzidine in various water samples
2 Experimental
21 Apparatus All absorption measurements were madeon a Shimadzu UV-210A double-beam spectrophotometersupplied with a digital printer DP80Z and matched 1 cmoptical silica cells
22 Reagents All reagents used were of analytical grade andobtained from Fluka and BDH companies
(1) TCNQ solution (1 times 10minus3M) is prepared freshly bydissolving 00102 g of 771015840881015840-tetracyanoquinodime-thane in absolute acetone or acetonitrile solventfor determination of aromatic or aliphatic aminesrespectively and diluted to the mark in 50mL volu-metric flask with the same solvent
(2) Standard solutions of primary aliphatic and aro-matic amines (100 120583gmL) are prepared individuallyby dissolving 001 g of pure amine(ethylamine 12-diaminopropane aniline m-aminophenol and ben-zidine) in 5mL ethanol and diluted to the markwith distilled water in 100mL volumetric flask Thesesolutions were further diluted with water to requiredconcentrations for working solutions
(3) Phosphate buffer solutions of pH values 602 986and 1065 were prepared by mixing various volumesof 02M potassium dihydrogen orthophosphate solu-tion with 02M potassium hydroxide solution andadjusted with pH meter type Philips (PW9420)
(4) Cetylpyridinium chloride (CPC) and cityltrimethy-lammonium bromide (CTAB) surfactants were pre-pared in 01 concentration by dissolving 01 g inwarm distilled water and the volume was completedto 100mL in calibrated flask
3 General Procedures
31 Determination of Primary Aliphatic Amines Aliquots ofstandard primary amine solutions of ethylamine and 12-diaminopropane were transferred separately into a series of10mL calibrated flasks To each of these were added 05 and10mL of 1 times 10minus3M TCNQ and the solutions were heatedat 40 and 50∘C for 20 and 30min for ethylamine and 12-diaminopropane respectively then the solutions were cooledto room temperature and diluted to the mark with distilledwater The absorbances of the complexes were measured at464 and 470 nm for the previous amines respectively againstcorresponding reagent blank
32 Determination of Primary Aromatic Amines Aliquots ofstandard primary amine solutions of aniline p-aminophenoland benzidine were transferred separately into a series of10mL calibrated flasks To each of these were added the opti-mum amounts of TCNQ phosphate buffer solution andCPC
01
310 350 390 430 470 510 550 590 630 670 710 750
290 310 330 350 370
02
03
04
05
06
07
Abso
rban
ce
(a)
(b)
(c)
Wavelength (nm) for (b) and (c)
Wavelength (nm) for (a)
Figure 1 Absorption spectra for the complexes of 05mL of1 times 10minus3M TCNQ with (a) 2120583gmL aniline (b) 2 120583gmL p-aminophenol and (c) 075 120583gmL benzidine versus blank reagent
660420 900820740500 580
01
02
03
05
04
Abso
rban
ce
Wavelength (nm )
(a)
(b)
Figure 2 Absorption spectra for the complexes of 05mL of 1 times10minus3M TCNQ and (a) 1 120583gmL ethylamine and (b) 2120583gmL 12-diaminopropane versus blank
(or CTAB in the case of benzidine) according to the orderof addition as listed in Table 3 The solutions were dilutedto the mark with distilled water and the absorbances of thecomplexes were measured at room temperature immediately(in the case of p-aminophenol the solutions were heated at40∘C for 5min and cooled to room temperature then dilutedto the mark with distilled water) at 323 511 and 500 nm foraniline p-aminophenol and benzidine respectively
4 Results and Discussion
41 Absorption Spectrum of the CT Complexes Primary aro-matic and aliphatic amines react with TCNQ in the presenceof phosphate buffer solution (in the case of aromatic amines)to give a red coloured complexes with maximum absorptionspectra at 511 500 464 and 470 nm for p-aminophenolbenzidine ethylamine and 12-diaminopropane respectivelywhereas aniline gave a yellow coloured complex at 323 nm(Figures 1 and 2) and their reagent blanks gave maximumabsorption at 320 nm for p-aminophenol and benzidine
Journal of Analytical Methods in Chemistry 3
whereas they gave it at 395 nm for aniline and 832 nm forethylamine and 12-diaminopropane under their optimumconditions
42 Effect of Solvent Different solvents such as acetonitrileacetone ethanol methanol dioxane and water were testedas reactionmedia for interaction between amines and TCNQ120587-acceptor It was found that TCNQ reagent reacted withprimary secondary and tertiary aliphatic and aromaticamines in the medium of previous solvents and produceddifferent colours but using water as a solvent for amines andacetonitrile or acetone for TCNQ and dilution with waterselective reactions between TCNQ and primary aliphatic andaromatic amines occurred and forming coloured 119899-120587 charge-transfer complexeswithmaximumabsorption at wavelengthsranged between 323 and 511 nm for given amines whereasother amines were either unreacted or gave low absorptionresponse Therefore this system of solvents is recommendedin our method
43 Effect of pH and Buffer Solutions The effect of pH onthe absorption of the complexes produced by the reactionof TCNQ with primary amines was studied using differentpHs ranging from 2 to 12 It was found that these complexesare formed in the final pH of 986 602 and 1065 for p-aminophenol aniline and benzidine respectively by addi-tion of NaOH solution and decreases in absorbances werefound through addition of HCl which may be attributedto the liberation of hydrogen cyanide whereas it was foundthat the absorbances of aliphatic amines were decreasedthrough addition of NaOH or HCl and the final pHs oftheir reaction solutions were 720 and 662 for ethylamineand 12-diaminopropane respectively Different buffers of thesame pHvalues as mentioned before were prepared by usingcarbonate borate phosphate ammonia and citrate buffers toinvestigate the sensitivity of the amine-TCNQ complexes Itwas found that phosphate buffer solution (KH
2PO4+ KOH)
increased the sensitivity for the aromatic amine-TCNQcomplexes (Table 1) and caused a bathochromic shift for p-aminophenol (460 997888rarr 475 nm) whereas the absorbances ofaliphatic amine-TCNQ complexes were decreased Howeverthe amounts of phosphate buffer solution at fixed pH valuesas cited before for aromatic amines were studied and foundto be 05 10 and 08mL which are the optimum amountsfor aniline p-aminophenol and benzidine respectively andwhich are recommended in the subsequent experiments
44 Effect of Reaction Time and Temperature The reactiontime was determined by following the color development atroom temperature (28∘C) and in thermostatically controlledwater bath at different temperatures up to 50 plusmn 1∘C Theabsorbance was measured at 5- and 10-minute intervalsagainst reagent blank treated similarly It was observedthat the absorbance reached maximum after addition ofthe reagent solution immediately at room temperature foraniline and benzidine after 5min at 40∘C for p-aminophenoland after 20 and 30min at 40 and 50∘C for ethylamineand 12-diaminopropane respectively and the stability of
Table 1 Effect of buffer solutions on the absorbance of aromaticamine-TCNQ complexes
Type of buffer solutionAbsorbance of TCNQ complex with
mdash mdash 0216lowastAbsorbance at 460 nmlowastlowastAbsorbance at 475 nm
their absorbances was achieved after cooling to the roomtemperature (Table 3)These temperatures and reaction timeswere chosen for colour development
45 Effect of TCNQ Concentration The effect of changingthe TCNQ concentration (02ndash20mL of 1 times 10minus3M) on theabsorbance of solution containing a fixed amount of eachprimary amine (10120583gmLminus1) was studied It is evident that theabsorbance increases with increasing TCNQ concentrationand reached maximum on using 05mL of 1 times 10minus3MTCNQ for aniline p-aminophenol benzidine and 12-diaminopropane and 10mL for ethylamine (Table 3)There-fore these concentrations were used in all subsequent work
46 Effect of Surfactant Effect of various surfactants includ-ing CTAB CPC tween-80 and triton x-100 of 01 concen-tration was tested It was found that the cationic surfactantsCPC and CATB caused a bathochromic shift with increasingin the sensitivity for aromatic amines (Table 2) while itdecreased the sensitivity of aliphatic amines However 05ndash30mL of 01 CPC were tested on the absorption of 25and 15 120583gmLminus1 aniline and p-aminophenol respectively and02ndash20mL of 01 CTAB on the absorption of 10 120583gmLminus1benzidine in the presence of phosphate buffer solution It wasfound that 05mL of CPC is the optimum amount for anilineand p-aminophenol and 1mL of CTAB for benzidine whichis recommended in subsequent experiments
47 Effect of Order of Addition In order to obtain the highcolour intensity the order of addition of reagents for aromaticamines should be followed as given in the Table 3 otherwisea loss in colour intensity was observed
However the optimum reaction conditions for develop-ing the colour intensity of primary amine-TCNQ complexesare summarized in Table 3
4 Journal of Analytical Methods in Chemistry
Table 2 Effect of surfactants on the absorption of aromatic amine-TCNQ complexes
Under the experimental conditions described in Table 3standard calibration curves of CT complexes for aliphatic andaromatic amines with TCNQ were constructed by plottingabsorbance versus concentrationThe correlation coefficientsranged from 09961 to 09993 indicating good linearityBeerrsquos law is obeyed in the ranges cited in Table 4 and themolar absorptivity values indicate the high sensitivity of themethod
6 Precision and Accuracy
Six replicate measurements are performed at three differentconcentrations of each amineThe relative standard deviationand recovery results indicated the high precision andaccuracy of the proposed method (Table 5)
7 Interferences
The interference from various organic nitrogen compoundsincluding secondary tertiary amines and amides in addition
to sodium chloride n-hexane and glucose on the deter-mination of 1 120583gmL of p-aminophenol (as an example forprimary aromatic amines) and 05120583gmL of ethylamine (asan example for primary aliphatic amines) was examined Itwas found that these compounds did not affect the recoveryin the range from 5 120583gmL of triethylamine to 2500120583gmL ofacrylamide for ethylamine and from 5 120583gmL of diethylamineto 100 120583gmL of acetanilide for p-aminophenol The resultsare summarized in Table 6
8 Application to Real Water Samples
The described method was applied to the analysis of ben-zidine in tap river and sea waters Three different concen-trations 25 50 and 10 120583gmL of benzidine were added tothe various filtered volumes of tap Dijlla river and syntheticsea waters [20] in final volume of 10mL and treated asdescribed in the previous general procedure The results inTable 7 indicated that benzidine could be determined in thepresence of small volumes of tap and river waters but aninterference was observed in the presence of small volumes
Journal of Analytical Methods in Chemistry 5
Table 5 Precision and accuracy data for primary amines determi-nation obtained by the proposed method
of sea water this may be attributed to the formation of metal-ligand complexes
9 Stoichiometry
The stoichiometry of the reaction of primary amines withTCNQ was studied by Jobrsquos method [21] using solutionsof equimolar (1 times 10minus3M) of each primary aliphatic andaromatic amines and TCNQ reagent (1 times 10minus4M in the caseof benzidine) The results obtained in Figure 3 show that 1 1amine to reagent was formed This indicates that only oneamino group is responsible for the formation of the products
10 Stability Constant ofAmine-TCNQ Complexes
The apparent stability constant was estimated by compar-ing the absorbance of a solution containing stoichiometricamounts of the primary amine and TCNQ (As) to onecontaining an excessive (optimum) amount of TCNQ reagent(Am) The average conditional stability constants of thecomplexes are calculated by the following equation
Kc = 1 minus 1205721205722119862
120572 = Am minus AsAm
(1)
where Kc is the association constant (Lsdotmolminus1) 120572 the dissoci-ation degree and 119862 the concentration of the complex whichis equal to the concentration of primary amine The resultsshown in Table 8 indicate that the complexes are relativelystable
11 Reaction Mechanism
The nature of the reaction between primary amines in aque-ous solution and TCNQ reagent is not clearly understoodMost of the spectrophotometric methods with TCNQ [22ndash26] are based on the charge-transfer interaction of radicalanion TCNQminus with the radical cation donors (D+) formed inacetonitrile medium leading to enhancement of the absorp-tion bands of TCNQ reagent in acetonitrile solvent at 840825 762 and 742 nm However in the present work it wasobserved that the complexes are formed in aqueous mediumin the ratio of 1 1 amine TCNQ with the appearance of anew absorption bands at 464 470 323 511 and 500 nmfor ethylamine 12-diaminopropane aniline p-aminophenoland benzidine respectively which is not shown by either ofthe components present in solution which may be attributedto the complete transfer of the unshared pair of electronson the nitrogen atom to TCNQ reagent and assigned as acharge-transfer complex absorption bands On this basis atentative reactionmechanismhas been proposed and given inScheme 1
12 Comparison with Other ReportedSpectrophotometric Methods
A comparison of some parameters linearity range andsensitivity of the current method with those of some otherreported spectrophotometric methods using different 120587-acceptors was described (Table 9) It is quite clear thatcurrent method is more sensitive than the reported methodsand all the charge-transfer complexes of TCNQ reagenthaving maximum absorption at visible regions except ofTCNQ-aniline complex appears at UV region
13 Conclusion
The proposed method is simple rapid sensitive and eco-nomical compared to already reported methods and does
6 Journal of Analytical Methods in Chemistry
Table 7 Determination of benzidine in different waters
Water Benzidine added (120583gmL) Recovery of benzidine found per mL of water005 01 03 05 10 15
not require any pretreatment of the primary amines orextraction procedure and has a good accuracy and precisionOn the other hand in terms of simplicity and expense themethod could be considered superior in comparison with thepreviously reported methods especially with those based onnonaqueous medium
References
[1] Kirk-Othmer Encyclopedia of Chemical Technology John Wileyamp Sons New York NY USA 3rd edition 1979
[2] E Psillakis andN Kalogerakis ldquoApplication of solventmicroex-traction to the analysis of nitroaromatic explosives in watersamplesrdquo Journal of Chromatography A vol 907 no 1-2 pp 211ndash219 2001
[3] R Belloli B Barletta E Bolzacchini S Meinardi M Orlandiand B Rindone ldquoDetermination of toxic nitrophenols inthe atmosphere by high-performance liquid chromatographyrdquoJournal of ChromatographyA vol 846 no 1-2 pp 277ndash281 1999
[4] J Namiesnik A Jastrzebska and B Zygmust ldquoDeterminationof volatile aliphatic amines in air by solid-phase microextrac-tion coupled with gas chromatography with flame ionizationdetectionrdquo Journal of Chromatography A vol 1016 no 1 pp 1ndash92003
[5] P C Dwivedi andA K Banga ldquoInteraction of primary aliphaticamines with chloranil Kinetic and spectroscopic studiesrdquoJournal of Physical Chemistry vol 85 no 12 pp 1768ndash1769 1981
[6] R E Smith and W R Davis ldquoSpectrophotometric determina-tion of amines with p-chloranilrdquo Analytical Chemistry vol 56no 13 pp 2345ndash2349 1984
[7] T N Al-Sabha Spectrophotometric micro determination of someorganic nitrogen compounds (amines and aldoximes) and theirbinary mixtures with chloranil [MS thesis] Mosul UniversityMosul Iraq 1984
[8] T N Al-Sabha The use of chargendashtransfer complex in selectivespectrophotometric determination of amines and application topharmaceutical preparations [PhD thesis] Mosul UniversityMosul Iraq 1997
8 Journal of Analytical Methods in Chemistry
[9] G K Hanna Application of charge transfer technique in traceanalysis [MS thesis] Mosul University Mosul Iraq 1986
[10] J O Singh J D Anunziata D Jorge and J J Silber ldquon-120587electron donor-acceptor complexes II Aliphatic amines withdinitrobenzenesrdquo Canadian Journal of Chemistry vol 63 no 4pp 903ndash907 1985
[11] L Forlani E Marianucci and P E Todesco ldquoCatalysis in nucle-ophilic aromatic substitution reactions Kinetic behaviour of 2-hydroxypyridine and related compounds in reaction between1-fluoro24-dinitrobenzene and aminesrdquo Gazzetta Chimica Ital-iana vol 122 p 9349 1992
[12] L Forlani ldquoCatalysis in nucleophilic aromatic substitutionreactionsThe presence of molecular complexes on the pathwayof reactions between 1-fluoro- and 1-chloro-24-dinitrobenzeneand aliphatic aminesrdquo Journal of the Chemical Society vol 8 pp1525ndash1530 1993
[13] R S Bakry A F M El Walily and S F Belal ldquoSpectropho-tometric determination of some phenolic sympathomimeticdrugs through reaction with 26-dihaloquinone chlorimidesrdquoMikrochimica Acta vol 127 no 1-2 pp 89ndash93 1997
[14] A S Amin G O El-Sayed and Y M Issa ldquoUtility of certain120587-acceptors for the spectrophotometric determination of nor-floxacinrdquo Analyst vol 120 no 4 pp 1189ndash1193 1995
[15] C S P Sastry K R Rao and D S Prasad ldquoDetermination ofcefadroxil by three simple spectrophotometric methods usingoxidative coupling reactionsrdquo Microchimica Acta vol 126 no1-2 pp 167ndash172 1997
[16] F A Aly F Belal and M I Walash ldquoColorimetric determina-tion of prenalterol hydrochloride in dosage formsrdquo Journal ofPharmaceutical and Biomedical Analysis vol 12 no 7 pp 955ndash958 1994
[17] F L Zhao B Z Xu Z Q Zhang and S Y Tong ldquoStudy onthe charge-transfer reaction between 7788-tetracyanoquinodi-methane and drugsrdquo Journal of Pharmaceutical and BiomedicalAnalysis vol 21 no 2 pp 355ndash360 1999
[18] C S P Sastry B S Sastry J V Rao and R R Krishna ldquoSpec-trophotometric methods for the determination of tolnaftaterdquoTalanta vol 40 no 4 pp 571ndash576 1993
[19] T N Al-Sabha and O A Al-Taee ldquoSpectrophotometric deter-mination of p-aminophenol and m-aminophenol in theiradmixture using tetracyanoethylene in aqueous mediumrdquo Jour-nal of National Chemistry vol 28 pp 572ndash584 2007
[20] A Henriksen ldquoAn automatic method for determining nitrateand nitrite in fresh and saline watersrdquo The Analyst vol 90 no1067 pp 83ndash88 1965
[21] P Job Spectrochemical Methods of Analysis Wiley IntersienceNew York NY USA 1971
[22] A Taha andG Rucker ldquoUtility of pi-acceptors in alkaloid assayrdquoArchiv Der Pharmazie vol 310 pp 485ndash494 1977
[23] H F Askal G A Saleh and N M Omar ldquoUtility of certain120587-acceptors for the spectrophotometric determination of somepenicillinsrdquo Analyst vol 116 no 4 pp 387ndash390 1991
[24] M M Abdel-Khalek M E Abdel-Hamid and M S MahrousldquoUse of 7788-tetracyanoquinodimethane in the colorimetricdetermination of some antihistaminesrdquo Journal of the Associa-tion of Official Analytical Chemists vol 68 no 5 pp 1057ndash10591985
[25] H Salem ldquoSpectrophotometric determination of 120573-adrenergicblocking agents in pharmaceutical formulationsrdquo Journal ofPharmaceutical and Biomedical Analysis vol 29 no 3 pp 527ndash538 2002
[26] G G Mohamed S M Khalil M A Zayed and M A E-HEl-Shall ldquo26-Dichloroquinone chlorimide and 7788-tetracy-anoquinodimethane reagents for the spectrophotometric deter-mination of salbutamol in pure and dosage formsrdquo Journal ofPharmaceutical and Biomedical Analysis vol 28 no 6 pp 1127ndash1133 2002
whereas they gave it at 395 nm for aniline and 832 nm forethylamine and 12-diaminopropane under their optimumconditions
42 Effect of Solvent Different solvents such as acetonitrileacetone ethanol methanol dioxane and water were testedas reactionmedia for interaction between amines and TCNQ120587-acceptor It was found that TCNQ reagent reacted withprimary secondary and tertiary aliphatic and aromaticamines in the medium of previous solvents and produceddifferent colours but using water as a solvent for amines andacetonitrile or acetone for TCNQ and dilution with waterselective reactions between TCNQ and primary aliphatic andaromatic amines occurred and forming coloured 119899-120587 charge-transfer complexeswithmaximumabsorption at wavelengthsranged between 323 and 511 nm for given amines whereasother amines were either unreacted or gave low absorptionresponse Therefore this system of solvents is recommendedin our method
43 Effect of pH and Buffer Solutions The effect of pH onthe absorption of the complexes produced by the reactionof TCNQ with primary amines was studied using differentpHs ranging from 2 to 12 It was found that these complexesare formed in the final pH of 986 602 and 1065 for p-aminophenol aniline and benzidine respectively by addi-tion of NaOH solution and decreases in absorbances werefound through addition of HCl which may be attributedto the liberation of hydrogen cyanide whereas it was foundthat the absorbances of aliphatic amines were decreasedthrough addition of NaOH or HCl and the final pHs oftheir reaction solutions were 720 and 662 for ethylamineand 12-diaminopropane respectively Different buffers of thesame pHvalues as mentioned before were prepared by usingcarbonate borate phosphate ammonia and citrate buffers toinvestigate the sensitivity of the amine-TCNQ complexes Itwas found that phosphate buffer solution (KH
2PO4+ KOH)
increased the sensitivity for the aromatic amine-TCNQcomplexes (Table 1) and caused a bathochromic shift for p-aminophenol (460 997888rarr 475 nm) whereas the absorbances ofaliphatic amine-TCNQ complexes were decreased Howeverthe amounts of phosphate buffer solution at fixed pH valuesas cited before for aromatic amines were studied and foundto be 05 10 and 08mL which are the optimum amountsfor aniline p-aminophenol and benzidine respectively andwhich are recommended in the subsequent experiments
44 Effect of Reaction Time and Temperature The reactiontime was determined by following the color development atroom temperature (28∘C) and in thermostatically controlledwater bath at different temperatures up to 50 plusmn 1∘C Theabsorbance was measured at 5- and 10-minute intervalsagainst reagent blank treated similarly It was observedthat the absorbance reached maximum after addition ofthe reagent solution immediately at room temperature foraniline and benzidine after 5min at 40∘C for p-aminophenoland after 20 and 30min at 40 and 50∘C for ethylamineand 12-diaminopropane respectively and the stability of
Table 1 Effect of buffer solutions on the absorbance of aromaticamine-TCNQ complexes
Type of buffer solutionAbsorbance of TCNQ complex with
mdash mdash 0216lowastAbsorbance at 460 nmlowastlowastAbsorbance at 475 nm
their absorbances was achieved after cooling to the roomtemperature (Table 3)These temperatures and reaction timeswere chosen for colour development
45 Effect of TCNQ Concentration The effect of changingthe TCNQ concentration (02ndash20mL of 1 times 10minus3M) on theabsorbance of solution containing a fixed amount of eachprimary amine (10120583gmLminus1) was studied It is evident that theabsorbance increases with increasing TCNQ concentrationand reached maximum on using 05mL of 1 times 10minus3MTCNQ for aniline p-aminophenol benzidine and 12-diaminopropane and 10mL for ethylamine (Table 3)There-fore these concentrations were used in all subsequent work
46 Effect of Surfactant Effect of various surfactants includ-ing CTAB CPC tween-80 and triton x-100 of 01 concen-tration was tested It was found that the cationic surfactantsCPC and CATB caused a bathochromic shift with increasingin the sensitivity for aromatic amines (Table 2) while itdecreased the sensitivity of aliphatic amines However 05ndash30mL of 01 CPC were tested on the absorption of 25and 15 120583gmLminus1 aniline and p-aminophenol respectively and02ndash20mL of 01 CTAB on the absorption of 10 120583gmLminus1benzidine in the presence of phosphate buffer solution It wasfound that 05mL of CPC is the optimum amount for anilineand p-aminophenol and 1mL of CTAB for benzidine whichis recommended in subsequent experiments
47 Effect of Order of Addition In order to obtain the highcolour intensity the order of addition of reagents for aromaticamines should be followed as given in the Table 3 otherwisea loss in colour intensity was observed
However the optimum reaction conditions for develop-ing the colour intensity of primary amine-TCNQ complexesare summarized in Table 3
4 Journal of Analytical Methods in Chemistry
Table 2 Effect of surfactants on the absorption of aromatic amine-TCNQ complexes
Under the experimental conditions described in Table 3standard calibration curves of CT complexes for aliphatic andaromatic amines with TCNQ were constructed by plottingabsorbance versus concentrationThe correlation coefficientsranged from 09961 to 09993 indicating good linearityBeerrsquos law is obeyed in the ranges cited in Table 4 and themolar absorptivity values indicate the high sensitivity of themethod
6 Precision and Accuracy
Six replicate measurements are performed at three differentconcentrations of each amineThe relative standard deviationand recovery results indicated the high precision andaccuracy of the proposed method (Table 5)
7 Interferences
The interference from various organic nitrogen compoundsincluding secondary tertiary amines and amides in addition
to sodium chloride n-hexane and glucose on the deter-mination of 1 120583gmL of p-aminophenol (as an example forprimary aromatic amines) and 05120583gmL of ethylamine (asan example for primary aliphatic amines) was examined Itwas found that these compounds did not affect the recoveryin the range from 5 120583gmL of triethylamine to 2500120583gmL ofacrylamide for ethylamine and from 5 120583gmL of diethylamineto 100 120583gmL of acetanilide for p-aminophenol The resultsare summarized in Table 6
8 Application to Real Water Samples
The described method was applied to the analysis of ben-zidine in tap river and sea waters Three different concen-trations 25 50 and 10 120583gmL of benzidine were added tothe various filtered volumes of tap Dijlla river and syntheticsea waters [20] in final volume of 10mL and treated asdescribed in the previous general procedure The results inTable 7 indicated that benzidine could be determined in thepresence of small volumes of tap and river waters but aninterference was observed in the presence of small volumes
Journal of Analytical Methods in Chemistry 5
Table 5 Precision and accuracy data for primary amines determi-nation obtained by the proposed method
of sea water this may be attributed to the formation of metal-ligand complexes
9 Stoichiometry
The stoichiometry of the reaction of primary amines withTCNQ was studied by Jobrsquos method [21] using solutionsof equimolar (1 times 10minus3M) of each primary aliphatic andaromatic amines and TCNQ reagent (1 times 10minus4M in the caseof benzidine) The results obtained in Figure 3 show that 1 1amine to reagent was formed This indicates that only oneamino group is responsible for the formation of the products
10 Stability Constant ofAmine-TCNQ Complexes
The apparent stability constant was estimated by compar-ing the absorbance of a solution containing stoichiometricamounts of the primary amine and TCNQ (As) to onecontaining an excessive (optimum) amount of TCNQ reagent(Am) The average conditional stability constants of thecomplexes are calculated by the following equation
Kc = 1 minus 1205721205722119862
120572 = Am minus AsAm
(1)
where Kc is the association constant (Lsdotmolminus1) 120572 the dissoci-ation degree and 119862 the concentration of the complex whichis equal to the concentration of primary amine The resultsshown in Table 8 indicate that the complexes are relativelystable
11 Reaction Mechanism
The nature of the reaction between primary amines in aque-ous solution and TCNQ reagent is not clearly understoodMost of the spectrophotometric methods with TCNQ [22ndash26] are based on the charge-transfer interaction of radicalanion TCNQminus with the radical cation donors (D+) formed inacetonitrile medium leading to enhancement of the absorp-tion bands of TCNQ reagent in acetonitrile solvent at 840825 762 and 742 nm However in the present work it wasobserved that the complexes are formed in aqueous mediumin the ratio of 1 1 amine TCNQ with the appearance of anew absorption bands at 464 470 323 511 and 500 nmfor ethylamine 12-diaminopropane aniline p-aminophenoland benzidine respectively which is not shown by either ofthe components present in solution which may be attributedto the complete transfer of the unshared pair of electronson the nitrogen atom to TCNQ reagent and assigned as acharge-transfer complex absorption bands On this basis atentative reactionmechanismhas been proposed and given inScheme 1
12 Comparison with Other ReportedSpectrophotometric Methods
A comparison of some parameters linearity range andsensitivity of the current method with those of some otherreported spectrophotometric methods using different 120587-acceptors was described (Table 9) It is quite clear thatcurrent method is more sensitive than the reported methodsand all the charge-transfer complexes of TCNQ reagenthaving maximum absorption at visible regions except ofTCNQ-aniline complex appears at UV region
13 Conclusion
The proposed method is simple rapid sensitive and eco-nomical compared to already reported methods and does
6 Journal of Analytical Methods in Chemistry
Table 7 Determination of benzidine in different waters
Water Benzidine added (120583gmL) Recovery of benzidine found per mL of water005 01 03 05 10 15
not require any pretreatment of the primary amines orextraction procedure and has a good accuracy and precisionOn the other hand in terms of simplicity and expense themethod could be considered superior in comparison with thepreviously reported methods especially with those based onnonaqueous medium
References
[1] Kirk-Othmer Encyclopedia of Chemical Technology John Wileyamp Sons New York NY USA 3rd edition 1979
[2] E Psillakis andN Kalogerakis ldquoApplication of solventmicroex-traction to the analysis of nitroaromatic explosives in watersamplesrdquo Journal of Chromatography A vol 907 no 1-2 pp 211ndash219 2001
[3] R Belloli B Barletta E Bolzacchini S Meinardi M Orlandiand B Rindone ldquoDetermination of toxic nitrophenols inthe atmosphere by high-performance liquid chromatographyrdquoJournal of ChromatographyA vol 846 no 1-2 pp 277ndash281 1999
[4] J Namiesnik A Jastrzebska and B Zygmust ldquoDeterminationof volatile aliphatic amines in air by solid-phase microextrac-tion coupled with gas chromatography with flame ionizationdetectionrdquo Journal of Chromatography A vol 1016 no 1 pp 1ndash92003
[5] P C Dwivedi andA K Banga ldquoInteraction of primary aliphaticamines with chloranil Kinetic and spectroscopic studiesrdquoJournal of Physical Chemistry vol 85 no 12 pp 1768ndash1769 1981
[6] R E Smith and W R Davis ldquoSpectrophotometric determina-tion of amines with p-chloranilrdquo Analytical Chemistry vol 56no 13 pp 2345ndash2349 1984
[7] T N Al-Sabha Spectrophotometric micro determination of someorganic nitrogen compounds (amines and aldoximes) and theirbinary mixtures with chloranil [MS thesis] Mosul UniversityMosul Iraq 1984
[8] T N Al-Sabha The use of chargendashtransfer complex in selectivespectrophotometric determination of amines and application topharmaceutical preparations [PhD thesis] Mosul UniversityMosul Iraq 1997
8 Journal of Analytical Methods in Chemistry
[9] G K Hanna Application of charge transfer technique in traceanalysis [MS thesis] Mosul University Mosul Iraq 1986
[10] J O Singh J D Anunziata D Jorge and J J Silber ldquon-120587electron donor-acceptor complexes II Aliphatic amines withdinitrobenzenesrdquo Canadian Journal of Chemistry vol 63 no 4pp 903ndash907 1985
[11] L Forlani E Marianucci and P E Todesco ldquoCatalysis in nucle-ophilic aromatic substitution reactions Kinetic behaviour of 2-hydroxypyridine and related compounds in reaction between1-fluoro24-dinitrobenzene and aminesrdquo Gazzetta Chimica Ital-iana vol 122 p 9349 1992
[12] L Forlani ldquoCatalysis in nucleophilic aromatic substitutionreactionsThe presence of molecular complexes on the pathwayof reactions between 1-fluoro- and 1-chloro-24-dinitrobenzeneand aliphatic aminesrdquo Journal of the Chemical Society vol 8 pp1525ndash1530 1993
[13] R S Bakry A F M El Walily and S F Belal ldquoSpectropho-tometric determination of some phenolic sympathomimeticdrugs through reaction with 26-dihaloquinone chlorimidesrdquoMikrochimica Acta vol 127 no 1-2 pp 89ndash93 1997
[14] A S Amin G O El-Sayed and Y M Issa ldquoUtility of certain120587-acceptors for the spectrophotometric determination of nor-floxacinrdquo Analyst vol 120 no 4 pp 1189ndash1193 1995
[15] C S P Sastry K R Rao and D S Prasad ldquoDetermination ofcefadroxil by three simple spectrophotometric methods usingoxidative coupling reactionsrdquo Microchimica Acta vol 126 no1-2 pp 167ndash172 1997
[16] F A Aly F Belal and M I Walash ldquoColorimetric determina-tion of prenalterol hydrochloride in dosage formsrdquo Journal ofPharmaceutical and Biomedical Analysis vol 12 no 7 pp 955ndash958 1994
[17] F L Zhao B Z Xu Z Q Zhang and S Y Tong ldquoStudy onthe charge-transfer reaction between 7788-tetracyanoquinodi-methane and drugsrdquo Journal of Pharmaceutical and BiomedicalAnalysis vol 21 no 2 pp 355ndash360 1999
[18] C S P Sastry B S Sastry J V Rao and R R Krishna ldquoSpec-trophotometric methods for the determination of tolnaftaterdquoTalanta vol 40 no 4 pp 571ndash576 1993
[19] T N Al-Sabha and O A Al-Taee ldquoSpectrophotometric deter-mination of p-aminophenol and m-aminophenol in theiradmixture using tetracyanoethylene in aqueous mediumrdquo Jour-nal of National Chemistry vol 28 pp 572ndash584 2007
[20] A Henriksen ldquoAn automatic method for determining nitrateand nitrite in fresh and saline watersrdquo The Analyst vol 90 no1067 pp 83ndash88 1965
[21] P Job Spectrochemical Methods of Analysis Wiley IntersienceNew York NY USA 1971
[22] A Taha andG Rucker ldquoUtility of pi-acceptors in alkaloid assayrdquoArchiv Der Pharmazie vol 310 pp 485ndash494 1977
[23] H F Askal G A Saleh and N M Omar ldquoUtility of certain120587-acceptors for the spectrophotometric determination of somepenicillinsrdquo Analyst vol 116 no 4 pp 387ndash390 1991
[24] M M Abdel-Khalek M E Abdel-Hamid and M S MahrousldquoUse of 7788-tetracyanoquinodimethane in the colorimetricdetermination of some antihistaminesrdquo Journal of the Associa-tion of Official Analytical Chemists vol 68 no 5 pp 1057ndash10591985
[25] H Salem ldquoSpectrophotometric determination of 120573-adrenergicblocking agents in pharmaceutical formulationsrdquo Journal ofPharmaceutical and Biomedical Analysis vol 29 no 3 pp 527ndash538 2002
[26] G G Mohamed S M Khalil M A Zayed and M A E-HEl-Shall ldquo26-Dichloroquinone chlorimide and 7788-tetracy-anoquinodimethane reagents for the spectrophotometric deter-mination of salbutamol in pure and dosage formsrdquo Journal ofPharmaceutical and Biomedical Analysis vol 28 no 6 pp 1127ndash1133 2002
Under the experimental conditions described in Table 3standard calibration curves of CT complexes for aliphatic andaromatic amines with TCNQ were constructed by plottingabsorbance versus concentrationThe correlation coefficientsranged from 09961 to 09993 indicating good linearityBeerrsquos law is obeyed in the ranges cited in Table 4 and themolar absorptivity values indicate the high sensitivity of themethod
6 Precision and Accuracy
Six replicate measurements are performed at three differentconcentrations of each amineThe relative standard deviationand recovery results indicated the high precision andaccuracy of the proposed method (Table 5)
7 Interferences
The interference from various organic nitrogen compoundsincluding secondary tertiary amines and amides in addition
to sodium chloride n-hexane and glucose on the deter-mination of 1 120583gmL of p-aminophenol (as an example forprimary aromatic amines) and 05120583gmL of ethylamine (asan example for primary aliphatic amines) was examined Itwas found that these compounds did not affect the recoveryin the range from 5 120583gmL of triethylamine to 2500120583gmL ofacrylamide for ethylamine and from 5 120583gmL of diethylamineto 100 120583gmL of acetanilide for p-aminophenol The resultsare summarized in Table 6
8 Application to Real Water Samples
The described method was applied to the analysis of ben-zidine in tap river and sea waters Three different concen-trations 25 50 and 10 120583gmL of benzidine were added tothe various filtered volumes of tap Dijlla river and syntheticsea waters [20] in final volume of 10mL and treated asdescribed in the previous general procedure The results inTable 7 indicated that benzidine could be determined in thepresence of small volumes of tap and river waters but aninterference was observed in the presence of small volumes
Journal of Analytical Methods in Chemistry 5
Table 5 Precision and accuracy data for primary amines determi-nation obtained by the proposed method
of sea water this may be attributed to the formation of metal-ligand complexes
9 Stoichiometry
The stoichiometry of the reaction of primary amines withTCNQ was studied by Jobrsquos method [21] using solutionsof equimolar (1 times 10minus3M) of each primary aliphatic andaromatic amines and TCNQ reagent (1 times 10minus4M in the caseof benzidine) The results obtained in Figure 3 show that 1 1amine to reagent was formed This indicates that only oneamino group is responsible for the formation of the products
10 Stability Constant ofAmine-TCNQ Complexes
The apparent stability constant was estimated by compar-ing the absorbance of a solution containing stoichiometricamounts of the primary amine and TCNQ (As) to onecontaining an excessive (optimum) amount of TCNQ reagent(Am) The average conditional stability constants of thecomplexes are calculated by the following equation
Kc = 1 minus 1205721205722119862
120572 = Am minus AsAm
(1)
where Kc is the association constant (Lsdotmolminus1) 120572 the dissoci-ation degree and 119862 the concentration of the complex whichis equal to the concentration of primary amine The resultsshown in Table 8 indicate that the complexes are relativelystable
11 Reaction Mechanism
The nature of the reaction between primary amines in aque-ous solution and TCNQ reagent is not clearly understoodMost of the spectrophotometric methods with TCNQ [22ndash26] are based on the charge-transfer interaction of radicalanion TCNQminus with the radical cation donors (D+) formed inacetonitrile medium leading to enhancement of the absorp-tion bands of TCNQ reagent in acetonitrile solvent at 840825 762 and 742 nm However in the present work it wasobserved that the complexes are formed in aqueous mediumin the ratio of 1 1 amine TCNQ with the appearance of anew absorption bands at 464 470 323 511 and 500 nmfor ethylamine 12-diaminopropane aniline p-aminophenoland benzidine respectively which is not shown by either ofthe components present in solution which may be attributedto the complete transfer of the unshared pair of electronson the nitrogen atom to TCNQ reagent and assigned as acharge-transfer complex absorption bands On this basis atentative reactionmechanismhas been proposed and given inScheme 1
12 Comparison with Other ReportedSpectrophotometric Methods
A comparison of some parameters linearity range andsensitivity of the current method with those of some otherreported spectrophotometric methods using different 120587-acceptors was described (Table 9) It is quite clear thatcurrent method is more sensitive than the reported methodsand all the charge-transfer complexes of TCNQ reagenthaving maximum absorption at visible regions except ofTCNQ-aniline complex appears at UV region
13 Conclusion
The proposed method is simple rapid sensitive and eco-nomical compared to already reported methods and does
6 Journal of Analytical Methods in Chemistry
Table 7 Determination of benzidine in different waters
Water Benzidine added (120583gmL) Recovery of benzidine found per mL of water005 01 03 05 10 15
not require any pretreatment of the primary amines orextraction procedure and has a good accuracy and precisionOn the other hand in terms of simplicity and expense themethod could be considered superior in comparison with thepreviously reported methods especially with those based onnonaqueous medium
References
[1] Kirk-Othmer Encyclopedia of Chemical Technology John Wileyamp Sons New York NY USA 3rd edition 1979
[2] E Psillakis andN Kalogerakis ldquoApplication of solventmicroex-traction to the analysis of nitroaromatic explosives in watersamplesrdquo Journal of Chromatography A vol 907 no 1-2 pp 211ndash219 2001
[3] R Belloli B Barletta E Bolzacchini S Meinardi M Orlandiand B Rindone ldquoDetermination of toxic nitrophenols inthe atmosphere by high-performance liquid chromatographyrdquoJournal of ChromatographyA vol 846 no 1-2 pp 277ndash281 1999
[4] J Namiesnik A Jastrzebska and B Zygmust ldquoDeterminationof volatile aliphatic amines in air by solid-phase microextrac-tion coupled with gas chromatography with flame ionizationdetectionrdquo Journal of Chromatography A vol 1016 no 1 pp 1ndash92003
[5] P C Dwivedi andA K Banga ldquoInteraction of primary aliphaticamines with chloranil Kinetic and spectroscopic studiesrdquoJournal of Physical Chemistry vol 85 no 12 pp 1768ndash1769 1981
[6] R E Smith and W R Davis ldquoSpectrophotometric determina-tion of amines with p-chloranilrdquo Analytical Chemistry vol 56no 13 pp 2345ndash2349 1984
[7] T N Al-Sabha Spectrophotometric micro determination of someorganic nitrogen compounds (amines and aldoximes) and theirbinary mixtures with chloranil [MS thesis] Mosul UniversityMosul Iraq 1984
[8] T N Al-Sabha The use of chargendashtransfer complex in selectivespectrophotometric determination of amines and application topharmaceutical preparations [PhD thesis] Mosul UniversityMosul Iraq 1997
8 Journal of Analytical Methods in Chemistry
[9] G K Hanna Application of charge transfer technique in traceanalysis [MS thesis] Mosul University Mosul Iraq 1986
[10] J O Singh J D Anunziata D Jorge and J J Silber ldquon-120587electron donor-acceptor complexes II Aliphatic amines withdinitrobenzenesrdquo Canadian Journal of Chemistry vol 63 no 4pp 903ndash907 1985
[11] L Forlani E Marianucci and P E Todesco ldquoCatalysis in nucle-ophilic aromatic substitution reactions Kinetic behaviour of 2-hydroxypyridine and related compounds in reaction between1-fluoro24-dinitrobenzene and aminesrdquo Gazzetta Chimica Ital-iana vol 122 p 9349 1992
[12] L Forlani ldquoCatalysis in nucleophilic aromatic substitutionreactionsThe presence of molecular complexes on the pathwayof reactions between 1-fluoro- and 1-chloro-24-dinitrobenzeneand aliphatic aminesrdquo Journal of the Chemical Society vol 8 pp1525ndash1530 1993
[13] R S Bakry A F M El Walily and S F Belal ldquoSpectropho-tometric determination of some phenolic sympathomimeticdrugs through reaction with 26-dihaloquinone chlorimidesrdquoMikrochimica Acta vol 127 no 1-2 pp 89ndash93 1997
[14] A S Amin G O El-Sayed and Y M Issa ldquoUtility of certain120587-acceptors for the spectrophotometric determination of nor-floxacinrdquo Analyst vol 120 no 4 pp 1189ndash1193 1995
[15] C S P Sastry K R Rao and D S Prasad ldquoDetermination ofcefadroxil by three simple spectrophotometric methods usingoxidative coupling reactionsrdquo Microchimica Acta vol 126 no1-2 pp 167ndash172 1997
[16] F A Aly F Belal and M I Walash ldquoColorimetric determina-tion of prenalterol hydrochloride in dosage formsrdquo Journal ofPharmaceutical and Biomedical Analysis vol 12 no 7 pp 955ndash958 1994
[17] F L Zhao B Z Xu Z Q Zhang and S Y Tong ldquoStudy onthe charge-transfer reaction between 7788-tetracyanoquinodi-methane and drugsrdquo Journal of Pharmaceutical and BiomedicalAnalysis vol 21 no 2 pp 355ndash360 1999
[18] C S P Sastry B S Sastry J V Rao and R R Krishna ldquoSpec-trophotometric methods for the determination of tolnaftaterdquoTalanta vol 40 no 4 pp 571ndash576 1993
[19] T N Al-Sabha and O A Al-Taee ldquoSpectrophotometric deter-mination of p-aminophenol and m-aminophenol in theiradmixture using tetracyanoethylene in aqueous mediumrdquo Jour-nal of National Chemistry vol 28 pp 572ndash584 2007
[20] A Henriksen ldquoAn automatic method for determining nitrateand nitrite in fresh and saline watersrdquo The Analyst vol 90 no1067 pp 83ndash88 1965
[21] P Job Spectrochemical Methods of Analysis Wiley IntersienceNew York NY USA 1971
[22] A Taha andG Rucker ldquoUtility of pi-acceptors in alkaloid assayrdquoArchiv Der Pharmazie vol 310 pp 485ndash494 1977
[23] H F Askal G A Saleh and N M Omar ldquoUtility of certain120587-acceptors for the spectrophotometric determination of somepenicillinsrdquo Analyst vol 116 no 4 pp 387ndash390 1991
[24] M M Abdel-Khalek M E Abdel-Hamid and M S MahrousldquoUse of 7788-tetracyanoquinodimethane in the colorimetricdetermination of some antihistaminesrdquo Journal of the Associa-tion of Official Analytical Chemists vol 68 no 5 pp 1057ndash10591985
[25] H Salem ldquoSpectrophotometric determination of 120573-adrenergicblocking agents in pharmaceutical formulationsrdquo Journal ofPharmaceutical and Biomedical Analysis vol 29 no 3 pp 527ndash538 2002
[26] G G Mohamed S M Khalil M A Zayed and M A E-HEl-Shall ldquo26-Dichloroquinone chlorimide and 7788-tetracy-anoquinodimethane reagents for the spectrophotometric deter-mination of salbutamol in pure and dosage formsrdquo Journal ofPharmaceutical and Biomedical Analysis vol 28 no 6 pp 1127ndash1133 2002
of sea water this may be attributed to the formation of metal-ligand complexes
9 Stoichiometry
The stoichiometry of the reaction of primary amines withTCNQ was studied by Jobrsquos method [21] using solutionsof equimolar (1 times 10minus3M) of each primary aliphatic andaromatic amines and TCNQ reagent (1 times 10minus4M in the caseof benzidine) The results obtained in Figure 3 show that 1 1amine to reagent was formed This indicates that only oneamino group is responsible for the formation of the products
10 Stability Constant ofAmine-TCNQ Complexes
The apparent stability constant was estimated by compar-ing the absorbance of a solution containing stoichiometricamounts of the primary amine and TCNQ (As) to onecontaining an excessive (optimum) amount of TCNQ reagent(Am) The average conditional stability constants of thecomplexes are calculated by the following equation
Kc = 1 minus 1205721205722119862
120572 = Am minus AsAm
(1)
where Kc is the association constant (Lsdotmolminus1) 120572 the dissoci-ation degree and 119862 the concentration of the complex whichis equal to the concentration of primary amine The resultsshown in Table 8 indicate that the complexes are relativelystable
11 Reaction Mechanism
The nature of the reaction between primary amines in aque-ous solution and TCNQ reagent is not clearly understoodMost of the spectrophotometric methods with TCNQ [22ndash26] are based on the charge-transfer interaction of radicalanion TCNQminus with the radical cation donors (D+) formed inacetonitrile medium leading to enhancement of the absorp-tion bands of TCNQ reagent in acetonitrile solvent at 840825 762 and 742 nm However in the present work it wasobserved that the complexes are formed in aqueous mediumin the ratio of 1 1 amine TCNQ with the appearance of anew absorption bands at 464 470 323 511 and 500 nmfor ethylamine 12-diaminopropane aniline p-aminophenoland benzidine respectively which is not shown by either ofthe components present in solution which may be attributedto the complete transfer of the unshared pair of electronson the nitrogen atom to TCNQ reagent and assigned as acharge-transfer complex absorption bands On this basis atentative reactionmechanismhas been proposed and given inScheme 1
12 Comparison with Other ReportedSpectrophotometric Methods
A comparison of some parameters linearity range andsensitivity of the current method with those of some otherreported spectrophotometric methods using different 120587-acceptors was described (Table 9) It is quite clear thatcurrent method is more sensitive than the reported methodsand all the charge-transfer complexes of TCNQ reagenthaving maximum absorption at visible regions except ofTCNQ-aniline complex appears at UV region
13 Conclusion
The proposed method is simple rapid sensitive and eco-nomical compared to already reported methods and does
6 Journal of Analytical Methods in Chemistry
Table 7 Determination of benzidine in different waters
Water Benzidine added (120583gmL) Recovery of benzidine found per mL of water005 01 03 05 10 15
not require any pretreatment of the primary amines orextraction procedure and has a good accuracy and precisionOn the other hand in terms of simplicity and expense themethod could be considered superior in comparison with thepreviously reported methods especially with those based onnonaqueous medium
References
[1] Kirk-Othmer Encyclopedia of Chemical Technology John Wileyamp Sons New York NY USA 3rd edition 1979
[2] E Psillakis andN Kalogerakis ldquoApplication of solventmicroex-traction to the analysis of nitroaromatic explosives in watersamplesrdquo Journal of Chromatography A vol 907 no 1-2 pp 211ndash219 2001
[3] R Belloli B Barletta E Bolzacchini S Meinardi M Orlandiand B Rindone ldquoDetermination of toxic nitrophenols inthe atmosphere by high-performance liquid chromatographyrdquoJournal of ChromatographyA vol 846 no 1-2 pp 277ndash281 1999
[4] J Namiesnik A Jastrzebska and B Zygmust ldquoDeterminationof volatile aliphatic amines in air by solid-phase microextrac-tion coupled with gas chromatography with flame ionizationdetectionrdquo Journal of Chromatography A vol 1016 no 1 pp 1ndash92003
[5] P C Dwivedi andA K Banga ldquoInteraction of primary aliphaticamines with chloranil Kinetic and spectroscopic studiesrdquoJournal of Physical Chemistry vol 85 no 12 pp 1768ndash1769 1981
[6] R E Smith and W R Davis ldquoSpectrophotometric determina-tion of amines with p-chloranilrdquo Analytical Chemistry vol 56no 13 pp 2345ndash2349 1984
[7] T N Al-Sabha Spectrophotometric micro determination of someorganic nitrogen compounds (amines and aldoximes) and theirbinary mixtures with chloranil [MS thesis] Mosul UniversityMosul Iraq 1984
[8] T N Al-Sabha The use of chargendashtransfer complex in selectivespectrophotometric determination of amines and application topharmaceutical preparations [PhD thesis] Mosul UniversityMosul Iraq 1997
8 Journal of Analytical Methods in Chemistry
[9] G K Hanna Application of charge transfer technique in traceanalysis [MS thesis] Mosul University Mosul Iraq 1986
[10] J O Singh J D Anunziata D Jorge and J J Silber ldquon-120587electron donor-acceptor complexes II Aliphatic amines withdinitrobenzenesrdquo Canadian Journal of Chemistry vol 63 no 4pp 903ndash907 1985
[11] L Forlani E Marianucci and P E Todesco ldquoCatalysis in nucle-ophilic aromatic substitution reactions Kinetic behaviour of 2-hydroxypyridine and related compounds in reaction between1-fluoro24-dinitrobenzene and aminesrdquo Gazzetta Chimica Ital-iana vol 122 p 9349 1992
[12] L Forlani ldquoCatalysis in nucleophilic aromatic substitutionreactionsThe presence of molecular complexes on the pathwayof reactions between 1-fluoro- and 1-chloro-24-dinitrobenzeneand aliphatic aminesrdquo Journal of the Chemical Society vol 8 pp1525ndash1530 1993
[13] R S Bakry A F M El Walily and S F Belal ldquoSpectropho-tometric determination of some phenolic sympathomimeticdrugs through reaction with 26-dihaloquinone chlorimidesrdquoMikrochimica Acta vol 127 no 1-2 pp 89ndash93 1997
[14] A S Amin G O El-Sayed and Y M Issa ldquoUtility of certain120587-acceptors for the spectrophotometric determination of nor-floxacinrdquo Analyst vol 120 no 4 pp 1189ndash1193 1995
[15] C S P Sastry K R Rao and D S Prasad ldquoDetermination ofcefadroxil by three simple spectrophotometric methods usingoxidative coupling reactionsrdquo Microchimica Acta vol 126 no1-2 pp 167ndash172 1997
[16] F A Aly F Belal and M I Walash ldquoColorimetric determina-tion of prenalterol hydrochloride in dosage formsrdquo Journal ofPharmaceutical and Biomedical Analysis vol 12 no 7 pp 955ndash958 1994
[17] F L Zhao B Z Xu Z Q Zhang and S Y Tong ldquoStudy onthe charge-transfer reaction between 7788-tetracyanoquinodi-methane and drugsrdquo Journal of Pharmaceutical and BiomedicalAnalysis vol 21 no 2 pp 355ndash360 1999
[18] C S P Sastry B S Sastry J V Rao and R R Krishna ldquoSpec-trophotometric methods for the determination of tolnaftaterdquoTalanta vol 40 no 4 pp 571ndash576 1993
[19] T N Al-Sabha and O A Al-Taee ldquoSpectrophotometric deter-mination of p-aminophenol and m-aminophenol in theiradmixture using tetracyanoethylene in aqueous mediumrdquo Jour-nal of National Chemistry vol 28 pp 572ndash584 2007
[20] A Henriksen ldquoAn automatic method for determining nitrateand nitrite in fresh and saline watersrdquo The Analyst vol 90 no1067 pp 83ndash88 1965
[21] P Job Spectrochemical Methods of Analysis Wiley IntersienceNew York NY USA 1971
[22] A Taha andG Rucker ldquoUtility of pi-acceptors in alkaloid assayrdquoArchiv Der Pharmazie vol 310 pp 485ndash494 1977
[23] H F Askal G A Saleh and N M Omar ldquoUtility of certain120587-acceptors for the spectrophotometric determination of somepenicillinsrdquo Analyst vol 116 no 4 pp 387ndash390 1991
[24] M M Abdel-Khalek M E Abdel-Hamid and M S MahrousldquoUse of 7788-tetracyanoquinodimethane in the colorimetricdetermination of some antihistaminesrdquo Journal of the Associa-tion of Official Analytical Chemists vol 68 no 5 pp 1057ndash10591985
[25] H Salem ldquoSpectrophotometric determination of 120573-adrenergicblocking agents in pharmaceutical formulationsrdquo Journal ofPharmaceutical and Biomedical Analysis vol 29 no 3 pp 527ndash538 2002
[26] G G Mohamed S M Khalil M A Zayed and M A E-HEl-Shall ldquo26-Dichloroquinone chlorimide and 7788-tetracy-anoquinodimethane reagents for the spectrophotometric deter-mination of salbutamol in pure and dosage formsrdquo Journal ofPharmaceutical and Biomedical Analysis vol 28 no 6 pp 1127ndash1133 2002
not require any pretreatment of the primary amines orextraction procedure and has a good accuracy and precisionOn the other hand in terms of simplicity and expense themethod could be considered superior in comparison with thepreviously reported methods especially with those based onnonaqueous medium
References
[1] Kirk-Othmer Encyclopedia of Chemical Technology John Wileyamp Sons New York NY USA 3rd edition 1979
[2] E Psillakis andN Kalogerakis ldquoApplication of solventmicroex-traction to the analysis of nitroaromatic explosives in watersamplesrdquo Journal of Chromatography A vol 907 no 1-2 pp 211ndash219 2001
[3] R Belloli B Barletta E Bolzacchini S Meinardi M Orlandiand B Rindone ldquoDetermination of toxic nitrophenols inthe atmosphere by high-performance liquid chromatographyrdquoJournal of ChromatographyA vol 846 no 1-2 pp 277ndash281 1999
[4] J Namiesnik A Jastrzebska and B Zygmust ldquoDeterminationof volatile aliphatic amines in air by solid-phase microextrac-tion coupled with gas chromatography with flame ionizationdetectionrdquo Journal of Chromatography A vol 1016 no 1 pp 1ndash92003
[5] P C Dwivedi andA K Banga ldquoInteraction of primary aliphaticamines with chloranil Kinetic and spectroscopic studiesrdquoJournal of Physical Chemistry vol 85 no 12 pp 1768ndash1769 1981
[6] R E Smith and W R Davis ldquoSpectrophotometric determina-tion of amines with p-chloranilrdquo Analytical Chemistry vol 56no 13 pp 2345ndash2349 1984
[7] T N Al-Sabha Spectrophotometric micro determination of someorganic nitrogen compounds (amines and aldoximes) and theirbinary mixtures with chloranil [MS thesis] Mosul UniversityMosul Iraq 1984
[8] T N Al-Sabha The use of chargendashtransfer complex in selectivespectrophotometric determination of amines and application topharmaceutical preparations [PhD thesis] Mosul UniversityMosul Iraq 1997
8 Journal of Analytical Methods in Chemistry
[9] G K Hanna Application of charge transfer technique in traceanalysis [MS thesis] Mosul University Mosul Iraq 1986
[10] J O Singh J D Anunziata D Jorge and J J Silber ldquon-120587electron donor-acceptor complexes II Aliphatic amines withdinitrobenzenesrdquo Canadian Journal of Chemistry vol 63 no 4pp 903ndash907 1985
[11] L Forlani E Marianucci and P E Todesco ldquoCatalysis in nucle-ophilic aromatic substitution reactions Kinetic behaviour of 2-hydroxypyridine and related compounds in reaction between1-fluoro24-dinitrobenzene and aminesrdquo Gazzetta Chimica Ital-iana vol 122 p 9349 1992
[12] L Forlani ldquoCatalysis in nucleophilic aromatic substitutionreactionsThe presence of molecular complexes on the pathwayof reactions between 1-fluoro- and 1-chloro-24-dinitrobenzeneand aliphatic aminesrdquo Journal of the Chemical Society vol 8 pp1525ndash1530 1993
[13] R S Bakry A F M El Walily and S F Belal ldquoSpectropho-tometric determination of some phenolic sympathomimeticdrugs through reaction with 26-dihaloquinone chlorimidesrdquoMikrochimica Acta vol 127 no 1-2 pp 89ndash93 1997
[14] A S Amin G O El-Sayed and Y M Issa ldquoUtility of certain120587-acceptors for the spectrophotometric determination of nor-floxacinrdquo Analyst vol 120 no 4 pp 1189ndash1193 1995
[15] C S P Sastry K R Rao and D S Prasad ldquoDetermination ofcefadroxil by three simple spectrophotometric methods usingoxidative coupling reactionsrdquo Microchimica Acta vol 126 no1-2 pp 167ndash172 1997
[16] F A Aly F Belal and M I Walash ldquoColorimetric determina-tion of prenalterol hydrochloride in dosage formsrdquo Journal ofPharmaceutical and Biomedical Analysis vol 12 no 7 pp 955ndash958 1994
[17] F L Zhao B Z Xu Z Q Zhang and S Y Tong ldquoStudy onthe charge-transfer reaction between 7788-tetracyanoquinodi-methane and drugsrdquo Journal of Pharmaceutical and BiomedicalAnalysis vol 21 no 2 pp 355ndash360 1999
[18] C S P Sastry B S Sastry J V Rao and R R Krishna ldquoSpec-trophotometric methods for the determination of tolnaftaterdquoTalanta vol 40 no 4 pp 571ndash576 1993
[19] T N Al-Sabha and O A Al-Taee ldquoSpectrophotometric deter-mination of p-aminophenol and m-aminophenol in theiradmixture using tetracyanoethylene in aqueous mediumrdquo Jour-nal of National Chemistry vol 28 pp 572ndash584 2007
[20] A Henriksen ldquoAn automatic method for determining nitrateand nitrite in fresh and saline watersrdquo The Analyst vol 90 no1067 pp 83ndash88 1965
[21] P Job Spectrochemical Methods of Analysis Wiley IntersienceNew York NY USA 1971
[22] A Taha andG Rucker ldquoUtility of pi-acceptors in alkaloid assayrdquoArchiv Der Pharmazie vol 310 pp 485ndash494 1977
[23] H F Askal G A Saleh and N M Omar ldquoUtility of certain120587-acceptors for the spectrophotometric determination of somepenicillinsrdquo Analyst vol 116 no 4 pp 387ndash390 1991
[24] M M Abdel-Khalek M E Abdel-Hamid and M S MahrousldquoUse of 7788-tetracyanoquinodimethane in the colorimetricdetermination of some antihistaminesrdquo Journal of the Associa-tion of Official Analytical Chemists vol 68 no 5 pp 1057ndash10591985
[25] H Salem ldquoSpectrophotometric determination of 120573-adrenergicblocking agents in pharmaceutical formulationsrdquo Journal ofPharmaceutical and Biomedical Analysis vol 29 no 3 pp 527ndash538 2002
[26] G G Mohamed S M Khalil M A Zayed and M A E-HEl-Shall ldquo26-Dichloroquinone chlorimide and 7788-tetracy-anoquinodimethane reagents for the spectrophotometric deter-mination of salbutamol in pure and dosage formsrdquo Journal ofPharmaceutical and Biomedical Analysis vol 28 no 6 pp 1127ndash1133 2002
not require any pretreatment of the primary amines orextraction procedure and has a good accuracy and precisionOn the other hand in terms of simplicity and expense themethod could be considered superior in comparison with thepreviously reported methods especially with those based onnonaqueous medium
References
[1] Kirk-Othmer Encyclopedia of Chemical Technology John Wileyamp Sons New York NY USA 3rd edition 1979
[2] E Psillakis andN Kalogerakis ldquoApplication of solventmicroex-traction to the analysis of nitroaromatic explosives in watersamplesrdquo Journal of Chromatography A vol 907 no 1-2 pp 211ndash219 2001
[3] R Belloli B Barletta E Bolzacchini S Meinardi M Orlandiand B Rindone ldquoDetermination of toxic nitrophenols inthe atmosphere by high-performance liquid chromatographyrdquoJournal of ChromatographyA vol 846 no 1-2 pp 277ndash281 1999
[4] J Namiesnik A Jastrzebska and B Zygmust ldquoDeterminationof volatile aliphatic amines in air by solid-phase microextrac-tion coupled with gas chromatography with flame ionizationdetectionrdquo Journal of Chromatography A vol 1016 no 1 pp 1ndash92003
[5] P C Dwivedi andA K Banga ldquoInteraction of primary aliphaticamines with chloranil Kinetic and spectroscopic studiesrdquoJournal of Physical Chemistry vol 85 no 12 pp 1768ndash1769 1981
[6] R E Smith and W R Davis ldquoSpectrophotometric determina-tion of amines with p-chloranilrdquo Analytical Chemistry vol 56no 13 pp 2345ndash2349 1984
[7] T N Al-Sabha Spectrophotometric micro determination of someorganic nitrogen compounds (amines and aldoximes) and theirbinary mixtures with chloranil [MS thesis] Mosul UniversityMosul Iraq 1984
[8] T N Al-Sabha The use of chargendashtransfer complex in selectivespectrophotometric determination of amines and application topharmaceutical preparations [PhD thesis] Mosul UniversityMosul Iraq 1997
8 Journal of Analytical Methods in Chemistry
[9] G K Hanna Application of charge transfer technique in traceanalysis [MS thesis] Mosul University Mosul Iraq 1986
[10] J O Singh J D Anunziata D Jorge and J J Silber ldquon-120587electron donor-acceptor complexes II Aliphatic amines withdinitrobenzenesrdquo Canadian Journal of Chemistry vol 63 no 4pp 903ndash907 1985
[11] L Forlani E Marianucci and P E Todesco ldquoCatalysis in nucle-ophilic aromatic substitution reactions Kinetic behaviour of 2-hydroxypyridine and related compounds in reaction between1-fluoro24-dinitrobenzene and aminesrdquo Gazzetta Chimica Ital-iana vol 122 p 9349 1992
[12] L Forlani ldquoCatalysis in nucleophilic aromatic substitutionreactionsThe presence of molecular complexes on the pathwayof reactions between 1-fluoro- and 1-chloro-24-dinitrobenzeneand aliphatic aminesrdquo Journal of the Chemical Society vol 8 pp1525ndash1530 1993
[13] R S Bakry A F M El Walily and S F Belal ldquoSpectropho-tometric determination of some phenolic sympathomimeticdrugs through reaction with 26-dihaloquinone chlorimidesrdquoMikrochimica Acta vol 127 no 1-2 pp 89ndash93 1997
[14] A S Amin G O El-Sayed and Y M Issa ldquoUtility of certain120587-acceptors for the spectrophotometric determination of nor-floxacinrdquo Analyst vol 120 no 4 pp 1189ndash1193 1995
[15] C S P Sastry K R Rao and D S Prasad ldquoDetermination ofcefadroxil by three simple spectrophotometric methods usingoxidative coupling reactionsrdquo Microchimica Acta vol 126 no1-2 pp 167ndash172 1997
[16] F A Aly F Belal and M I Walash ldquoColorimetric determina-tion of prenalterol hydrochloride in dosage formsrdquo Journal ofPharmaceutical and Biomedical Analysis vol 12 no 7 pp 955ndash958 1994
[17] F L Zhao B Z Xu Z Q Zhang and S Y Tong ldquoStudy onthe charge-transfer reaction between 7788-tetracyanoquinodi-methane and drugsrdquo Journal of Pharmaceutical and BiomedicalAnalysis vol 21 no 2 pp 355ndash360 1999
[18] C S P Sastry B S Sastry J V Rao and R R Krishna ldquoSpec-trophotometric methods for the determination of tolnaftaterdquoTalanta vol 40 no 4 pp 571ndash576 1993
[19] T N Al-Sabha and O A Al-Taee ldquoSpectrophotometric deter-mination of p-aminophenol and m-aminophenol in theiradmixture using tetracyanoethylene in aqueous mediumrdquo Jour-nal of National Chemistry vol 28 pp 572ndash584 2007
[20] A Henriksen ldquoAn automatic method for determining nitrateand nitrite in fresh and saline watersrdquo The Analyst vol 90 no1067 pp 83ndash88 1965
[21] P Job Spectrochemical Methods of Analysis Wiley IntersienceNew York NY USA 1971
[22] A Taha andG Rucker ldquoUtility of pi-acceptors in alkaloid assayrdquoArchiv Der Pharmazie vol 310 pp 485ndash494 1977
[23] H F Askal G A Saleh and N M Omar ldquoUtility of certain120587-acceptors for the spectrophotometric determination of somepenicillinsrdquo Analyst vol 116 no 4 pp 387ndash390 1991
[24] M M Abdel-Khalek M E Abdel-Hamid and M S MahrousldquoUse of 7788-tetracyanoquinodimethane in the colorimetricdetermination of some antihistaminesrdquo Journal of the Associa-tion of Official Analytical Chemists vol 68 no 5 pp 1057ndash10591985
[25] H Salem ldquoSpectrophotometric determination of 120573-adrenergicblocking agents in pharmaceutical formulationsrdquo Journal ofPharmaceutical and Biomedical Analysis vol 29 no 3 pp 527ndash538 2002
[26] G G Mohamed S M Khalil M A Zayed and M A E-HEl-Shall ldquo26-Dichloroquinone chlorimide and 7788-tetracy-anoquinodimethane reagents for the spectrophotometric deter-mination of salbutamol in pure and dosage formsrdquo Journal ofPharmaceutical and Biomedical Analysis vol 28 no 6 pp 1127ndash1133 2002
[9] G K Hanna Application of charge transfer technique in traceanalysis [MS thesis] Mosul University Mosul Iraq 1986
[10] J O Singh J D Anunziata D Jorge and J J Silber ldquon-120587electron donor-acceptor complexes II Aliphatic amines withdinitrobenzenesrdquo Canadian Journal of Chemistry vol 63 no 4pp 903ndash907 1985
[11] L Forlani E Marianucci and P E Todesco ldquoCatalysis in nucle-ophilic aromatic substitution reactions Kinetic behaviour of 2-hydroxypyridine and related compounds in reaction between1-fluoro24-dinitrobenzene and aminesrdquo Gazzetta Chimica Ital-iana vol 122 p 9349 1992
[12] L Forlani ldquoCatalysis in nucleophilic aromatic substitutionreactionsThe presence of molecular complexes on the pathwayof reactions between 1-fluoro- and 1-chloro-24-dinitrobenzeneand aliphatic aminesrdquo Journal of the Chemical Society vol 8 pp1525ndash1530 1993
[13] R S Bakry A F M El Walily and S F Belal ldquoSpectropho-tometric determination of some phenolic sympathomimeticdrugs through reaction with 26-dihaloquinone chlorimidesrdquoMikrochimica Acta vol 127 no 1-2 pp 89ndash93 1997
[14] A S Amin G O El-Sayed and Y M Issa ldquoUtility of certain120587-acceptors for the spectrophotometric determination of nor-floxacinrdquo Analyst vol 120 no 4 pp 1189ndash1193 1995
[15] C S P Sastry K R Rao and D S Prasad ldquoDetermination ofcefadroxil by three simple spectrophotometric methods usingoxidative coupling reactionsrdquo Microchimica Acta vol 126 no1-2 pp 167ndash172 1997
[16] F A Aly F Belal and M I Walash ldquoColorimetric determina-tion of prenalterol hydrochloride in dosage formsrdquo Journal ofPharmaceutical and Biomedical Analysis vol 12 no 7 pp 955ndash958 1994
[17] F L Zhao B Z Xu Z Q Zhang and S Y Tong ldquoStudy onthe charge-transfer reaction between 7788-tetracyanoquinodi-methane and drugsrdquo Journal of Pharmaceutical and BiomedicalAnalysis vol 21 no 2 pp 355ndash360 1999
[18] C S P Sastry B S Sastry J V Rao and R R Krishna ldquoSpec-trophotometric methods for the determination of tolnaftaterdquoTalanta vol 40 no 4 pp 571ndash576 1993
[19] T N Al-Sabha and O A Al-Taee ldquoSpectrophotometric deter-mination of p-aminophenol and m-aminophenol in theiradmixture using tetracyanoethylene in aqueous mediumrdquo Jour-nal of National Chemistry vol 28 pp 572ndash584 2007
[20] A Henriksen ldquoAn automatic method for determining nitrateand nitrite in fresh and saline watersrdquo The Analyst vol 90 no1067 pp 83ndash88 1965
[21] P Job Spectrochemical Methods of Analysis Wiley IntersienceNew York NY USA 1971
[22] A Taha andG Rucker ldquoUtility of pi-acceptors in alkaloid assayrdquoArchiv Der Pharmazie vol 310 pp 485ndash494 1977
[23] H F Askal G A Saleh and N M Omar ldquoUtility of certain120587-acceptors for the spectrophotometric determination of somepenicillinsrdquo Analyst vol 116 no 4 pp 387ndash390 1991
[24] M M Abdel-Khalek M E Abdel-Hamid and M S MahrousldquoUse of 7788-tetracyanoquinodimethane in the colorimetricdetermination of some antihistaminesrdquo Journal of the Associa-tion of Official Analytical Chemists vol 68 no 5 pp 1057ndash10591985
[25] H Salem ldquoSpectrophotometric determination of 120573-adrenergicblocking agents in pharmaceutical formulationsrdquo Journal ofPharmaceutical and Biomedical Analysis vol 29 no 3 pp 527ndash538 2002
[26] G G Mohamed S M Khalil M A Zayed and M A E-HEl-Shall ldquo26-Dichloroquinone chlorimide and 7788-tetracy-anoquinodimethane reagents for the spectrophotometric deter-mination of salbutamol in pure and dosage formsrdquo Journal ofPharmaceutical and Biomedical Analysis vol 28 no 6 pp 1127ndash1133 2002
![3 all 1A).QP24.pdfWrite an equation to show the production of 4-aminophenol from 4-nitrophenol. Use [H] ... The flowchart below shows some reactions of 4-aminophenol. NH 3 ... shown](https://static.documents.pub/doc/80x56/607c53492aba8b596000ab7a/3-all-1-aqp24pdf-write-an-equation-to-show-the-production-of-4-aminophenol-from.jpg)
