This article was downloaded by: [Aston University] On: 09 January 2014, At: 00:27 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK Analytical Letters Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/lanl20 Determination of Organotin Compounds in Wine by Microwave-Assisted Extraction and High Performance Liquid Chromatography–Inductively Coupled Plasma Mass Spectrometry Ying-Xia Liu a , Yi-Qun Wan a b & Lan Guo a a State Key Laboratory of Food Science and Technology , Nanchang University , Nanchang , P. R. China b Center of Analysis and Testing , Nanchang University , Nanchang , P. R. China Accepted author version posted online: 12 Sep 2013.Published online: 31 Dec 2013. To cite this article: Ying-Xia Liu , Yi-Qun Wan & Lan Guo (2014) Determination of Organotin Compounds in Wine by Microwave-Assisted Extraction and High Performance Liquid Chromatography–Inductively Coupled Plasma Mass Spectrometry, Analytical Letters, 47:2, 343-355, DOI: 10.1080/00032719.2013.834445 To link to this article: http://dx.doi.org/10.1080/00032719.2013.834445 PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms &
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This article was downloaded by: [Aston University]On: 09 January 2014, At: 00:27Publisher: Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954 Registeredoffice: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
Analytical LettersPublication details, including instructions for authors andsubscription information:http://www.tandfonline.com/loi/lanl20
Determination of Organotin Compoundsin Wine by Microwave-AssistedExtraction and High Performance LiquidChromatography–Inductively CoupledPlasma Mass SpectrometryYing-Xia Liu a , Yi-Qun Wan a b & Lan Guo aa State Key Laboratory of Food Science and Technology , NanchangUniversity , Nanchang , P. R. Chinab Center of Analysis and Testing , Nanchang University , Nanchang ,P. R. ChinaAccepted author version posted online: 12 Sep 2013.Publishedonline: 31 Dec 2013.
To cite this article: Ying-Xia Liu , Yi-Qun Wan & Lan Guo (2014) Determination of OrganotinCompounds in Wine by Microwave-Assisted Extraction and High Performance LiquidChromatography–Inductively Coupled Plasma Mass Spectrometry, Analytical Letters, 47:2, 343-355,DOI: 10.1080/00032719.2013.834445
To link to this article: http://dx.doi.org/10.1080/00032719.2013.834445
PLEASE SCROLL DOWN FOR ARTICLE
Taylor & Francis makes every effort to ensure the accuracy of all the information (the“Content”) contained in the publications on our platform. However, Taylor & Francis,our agents, and our licensors make no representations or warranties whatsoever as tothe accuracy, completeness, or suitability for any purpose of the Content. Any opinionsand views expressed in this publication are the opinions and views of the authors,and are not the views of or endorsed by Taylor & Francis. The accuracy of the Contentshould not be relied upon and should be independently verified with primary sourcesof information. Taylor and Francis shall not be liable for any losses, actions, claims,proceedings, demands, costs, expenses, damages, and other liabilities whatsoever orhowsoever caused arising directly or indirectly in connection with, in relation to or arisingout of the use of the Content.
This article may be used for research, teaching, and private study purposes. Anysubstantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,systematic supply, or distribution in any form to anyone is expressly forbidden. Terms &
DETERMINATION OF ORGANOTIN COMPOUNDS INWINE BY MICROWAVE-ASSISTED EXTRACTION ANDHIGH PERFORMANCE LIQUID CHROMATOGRAPHY–INDUCTIVELY COUPLED PLASMA MASSSPECTROMETRY
Ying-Xia Liu,1 Yi-Qun Wan,1,2 and Lan Guo11State Key Laboratory of Food Science and Technology, NanchangUniversity, Nanchang, P. R. China2Center of Analysis and Testing, Nanchang University, Nanchang,P. R. China
A new analytical procedure for the determination of five organotin compounds in several
matrix wine samples is reported. The organotin compounds were extracted by microwave-
assisted extraction with n-hexane. Extraction conditions, such as volume of n-hexane
required, extraction temperature, and extraction time, were investigated and optimized
by an orthogonal array experimental design. The determination of organotin compounds
in the final extracts was carried out by liquid chromatography–inductively coupled plasma
mass spectrometry. The procedure showed limits of detection between 0.029–0.049lg �L�1.
The linearity was in the range of 0.5 to 100lg �L�1. The precision expressed as relative
standard deviation (RSD) was below 9.43%. The developed method was successfully
employed to analyze different matrix wine samples, and some analytes were detected at
the level of 0.053 to 1.14lg �L�1.
Keywords: Liquid chromatography–inductively coupled plasma mass spectrometry; Microwave-assisted
extraction; Organotin compounds; Wine
INTRODUCTION
The extensive use of organotin compounds has inflicted great adverse impacton the environment for more than 50 years. Tributyltin (TBT) and triphenyltin(TPhT) are employed as wood preservers or pesticides. Dimethyltin (DMT) and
Received 14 May 2013; accepted 31 July 2013.
The financial support of this study from the National Key Technology R & D Program of the ‘‘12th
Five-Year Plan’’ (2012BAK17B02), the Natural Science Foundation of China (20965005), and the
Research Program of State Key Laboratory of Food Science and Technology of Nanchang University
(SKLF-ZZB-201304) are gratefully acknowledged.
Address correspondence to Yi-Qun Wan, State Key Laboratory of Food Science and Technology,
Center of Analysis and Testing, Nanchang University, Nanchang 330047, China. E-mail: wanyiqun@
ncu.edu.cn
Analytical Letters, 47: 343–355, 2014
Copyright # Taylor & Francis Group, LLC
ISSN: 0003-2719 print=1532-236X online
DOI: 10.1080/00032719.2013.834445
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dibutyltin (DBT) are widely used as heat stabilizers in rigid polyvinyl-chloride resins(van Dokkum and Huwer 2005; van Mol, Alcott, and Allendorf 2005). Most orga-notin compounds show a wide range of toxic effects for humans; the exact level oftoxicity depends on the compound used. It is well-known that the organic speciesof tin are more toxic than the inorganic forms, with trisubstituted species beingthe most toxic followed by disubstituted and monosubstituted (Kuballa et al.1995; Rivas et al. 1996). The toxicity of these compounds has resulted in numerousadverse biological effects on nontarget organisms. Thus far, organotins have beenregarded as priority pollutants by the European Union both in the PollutantEmission Register (European Commission 2000b) and in the Water FrameworkDirective (European Commission 2000a).
According to culture of wine and the wine-making, organotin compounds mayalso be present in wines (Heroult et al. 2008; Azenha et al. 2008). The frequent appli-cation of chemicals to control pests may contaminate the main raw materials of winesuch as rice, wheat, and grapes. Wine may also be contaminated by organotin com-pounds in wine production, processing, and transportation engineering, especiallywhen some wine was packaged in plastic bottles and agglomerated cork stoppers(Jiang, Liu, and Zhou 2004). Therefore, the analysis and monitoring of organotincompounds in wine samples are extremely important.
Monitoring elemental species requires selective and sensitive analytical meth-ods to resolve and quantify the different species at low levels. The reviews on thespeciation of organotins in wines mostly focus on coupling gas chromatography(GC) with different detectors, such as the atomic emission detector (AED) (Campilloet al. 2012), mass spectrometry (MS) (Wan, Ma, and Mao 2012; Azenha et al. 2008),and pulsed flame photometric detection (PFPD) (Heroult et al. 2008). GC showshigh resolution power and sensitivity. However, the major limitation of these meth-ods is that organotins have to be off-line derivatized with sodium borohydride,sodium tetraethylborate (Montes et al. 2009), or Grignard reagents (Zhao et al.2008). The derivatization step is time-consuming and may alter speciation.
High performance liquid chromatography (HPLC) coupled with differentdetectors, such as atomic absorption spectrometery (AAS) (Rychlovsky, Cernoch,and Sklenickova 2002), electrospray ionization mass spectrometry (ESI-MS) (ElAtrache, Tortajada, and Dachraoui 2011) and inductively coupled plasma atomicemission spectrometery (ICP-AES) (Rivaro, Frache, and Leardi 1997) are widelyused for the speciation of organotins. HPLC offer the advantage that derivatizationis not required, which eliminates a potential source of uncertainty in the final resultsand can reduce analysis time significantly. Among these detectors coupled to HPLCfor the analysis of organotins, inductively coupled plasma mass spectrometry(ICP-MS) offers excellent sensitivity, wide linear dynamic range, high-speed analysis,and the ability to perform isotopic analysis (Yu et al. 2010; 2009).
Numerous studies have reported on the determination of organotin compoundsusing HPLC coupled with ICP-MS focused on sediments (Dubiella-Jackowska et al.2007), human urine (Suzuki et al. 2008), seawater (Zhai et al. 2008; Ugarte et al.2009), and seafood (Yu et al. 2010). However, the samples that were studied in pre-vious research based on GC were limited to one kind of alcoholic product, such asbrandy or champagne. A minimal amount of research has been reported thus faron tin speciation in different matrix wine samples using HPLC–ICP-MS.
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A high throughput microwave-assisted extraction (MAE) method was recentlyused to determine organotin compounds (Zuliani et al. 2010) in different samples.Microwave-assisted extraction shows good efficiency with lower relative standarddeviation and also reduces the volume of solvent and time. The investigation hasrevealed that microwave extraction is a more environmental friendly process com-pared to current methods such as ultrasonic assisted extraction, Soxhlet extraction,and liquid–liquid extraction (Borges et al. 2008; Huang et al. 2013). Microwavetechniques have been developed as an important means of extracting chemical pol-lutants from different matrices (Montesdeoca-Esponda, Sosa-Ferrera, and Santana-Rodriguez 2013; Fang et al. 2012; Mao et al. 2012) and are gaining an important rolein sample preparation.
In this work, a simple and rapid procedure for the determination of the orga-notin compounds in several wine matrices by HPLC–ICP-MS has been developed.To the best of our knowledge, it is the first time that the five organotin compoundsincluding dimethyltin dichloride, dibutyltin dichloride, tributyltin chloride, diphenyl-tin dichloride, and triphenyltin chloride, were extracted by a microwave techniqueand determined by HPLC–ICP-MS in several matrix wine samples. The comparativeresults are listed in Table 1 and demonstrate that the limits of detection for organo-tins in our results are better than our previous work (Wan et al. 2012) and lower thanor comparable to those of the reported methods.
MATERIALS AND METHODS
Standards and Reagents
Five organotin standards including dimethyltin dichloride (DMT, 98.0%),diphenyltin dichloride (DPhT, 97.0%), dibutyltin dichloride (DBT, 97.0%), triphe-nyltin chloride (TPhT, 96.0%), and tributyltin chloride (TBT, 96.5%) were purchased
Table 1. Comparison of the present technique with reported methods
Sample Species
Extracting
method
Method of
detection
Detection
limit
(ngmL�1) Reference
Verde white, red,
white and Port
wines
MBT, DBT, TBT SPME GC-MS 0.01–0.2 Azenha and
Vasconcelo
2002
Grapes and white
wine
FBTO MSPD-
SPME
GC-AED 0.05–0.1 Montes et al.
2009
Grapes wine MBT, DBT, TBT LLE GC-FPD 0.18–0.29 Jiang et al. 2004
from Dr. Ehrenstorfer (Germany). Standard stock solutions of organotins (100mg �L�1) were prepared in methanol. Working standards at various concentrations wereprepared from stock solutions by dilution in methanol. All the standards were storedin the dark at 4�C.
Chromatographic grade methanol was purchased from Merck Company(Darmstadt, Germany). Dichloromethane, n-hexane, glacial acetic acid, and triethyl-amine of analytical grade were purchased from Shanghai Reagent Company(Shanghai, China). The pH value of the buffer solution was adjusted by addingtriethylamine in 10% glacial acetic acid (v=v) and monitored using a pH-meter.
Instrumentation
A pHS-3 digital pH-meter was obtained from Shanghai Rex Device Works,(Shanghai, China). For concentrating the extracts, a RE-52A rotary vacuum evap-orator (Shanghai Yarong Biochemistry Instrument Factory, Shanghai, China) wasused. The deionized water was prepared by a Milli-Q Water system (Millipore,Bedford, MA, USA). The extraction procedure was performed by an Ethos Micro-wave Apparatus (Milestone, Italy). DMT, DPhT, DBT, TPhT, and TBT were sepa-rated by an HPLC system (Prostar 210, Varian Technologies, USA) using a reversedphase polymer column, Pursuit 5m-C18 column (250� 4.6mm i.d., Varian Technol-ogies, USA). Data evaluation was performed using Galaxie software supplied withthe ICP-MS (Varian 820 ICP-MS, Varian Technologies, USA). High performanceliquid chromatography– tandem mass spectrometry (HPLC-MS=MS) confirmationwas carried out using an Agilent Technologies 1200 network LC system with aZorbax Eclipse plus C18 column (2.1� 50mm, 1.8 mm, Agilent Technologies, USA).
Samples
Ten wine samples that were respectively produced by different companies werepurchased from local markets in Nanchang, P. R. China. They were chosen on thebasis of sample matrices, according to their raw materials, production process, andstorage. Four red wine samples distilled from grapes were held in dark-colored bot-tles; the alcohol percentages (APs) were 11.5%, 11.5%, 7%, and 12%, respectively.Two white wine samples were held in colorless glass bottles, and the other two wereheld in plastic bottles. The alcohol percentages were 50%, 50%, 42%, and 42%,respectively, and the main raw materials of these four samples were rice and wheat.The two kinds of yellow wines made of glutinous rice and wheat were both held indark-colored bottles; the alcohol percentages were 16.5% and 13%.
Sample Preparation
A microwave apparatus was used to extract samples, and the extraction wasperformed in the temperature mode. A 20-mL wine sample was put into theTeflonline extraction vessels, and 20mL n-hexane containing 0.02% tropolone (w=v)was added. The extraction temperature was 100�C and programmed as follows:ramped to 100�C for 10min, held at 100�C for 10min, and decreased to roomtemperature for 20min. When the extraction was completed, the extracts were
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centrifuged at 4000 rpm for 10min. The portion of supernatant was transferred intoa 50-mL round-bottom flask and evaporated to dryness using a rotary vacuum evap-orator in a water bath with the temperature of 28�C. Finally, the residue was dis-solved with 2mL methanol and filtered through a 0.22-mm organic membranebefore LC–ICP-MS analysis.
Chromatographic Analysis
DMT, DPhT, DBT, TPhT, and TBT were separated by HPLC using a reversedphase polymer column. Methanol-10% glacial acetic acid in water was used as themobile phase for the separation of both groups (tri- and di- substituted) of the ana-lytes by gradient elution. Ten percent glacial acetic acid in deionized water wasadjusted to a pH of to 3.0 with (A) triethylamine and (B) methanol with the follow-ing gradient: 0.0 to 22.0min: hold 35% A=65% B; 22.0 to 26.0min: linear from 35%A=65% B to 15% A=85% B; 26.0 to 40.0min: hold 15% A=85% B, with a flow rate of0.5mLmin�1. The column temperature selected was 30�C and the injector volumewas 20 mL. DMT, DPhT, DBT, TPhT, and TBT were eluted at 7.2, 9.7, 16.6,24.5, and 37.7min, respectively. The effluent from the column was directly connectedto the nebulizer with peek tubing and a low dead volume connector. Data evaluationwas performed using the Galaxie software supplied with the ICP–MS, and quanti-fication was based on peak area by m=z 120 (120Snþ). The optimum experimentalconditions for ICP-MS are provided in Table 2.
In order to further confirm the analytical results of HPLC–ICP-MS, LC–MS=MS was introduced. Ten-microliter portions of wine samples extracted withn-hexane was injected into an HPLC system with a Zorbaz Eclipse plus C18 columnunder the following conditions: mobile phase, methanol-10mmol �L�1 ammoniumformate containing 0.1% formic acid; flow rate, 0.3mLmin�1; column temperature,25�C; the volume of injection, 10 mL. The mass spectrometry parameters were anebulizer gas pressure of 40 psi, capillary temperature of 350�C, capillary voltageof 4.0 kV, and a scan mode, m=z [MþH] þ. The parameters of multiple reactionmonitoring (MRM) (m=z 50 to m=z 500) for the three organotins are shown in detailin Table 3.
Table 2. ICP-MS operating conditions for the analysis of
organotins in wine samples
Parameter Optimized value
Radio frequency power 1400W
Plasma Ar flow 18.0Lmin�1
Auxiliary Ar flow 1.8Lmin�1
Nebulizer Ar flow 0.96Lmin�1
Oxygen flow 0.25Lmin�1
Data acquisition mode time resolved analysis
Dwell time 10000ms
Scan mode peak hopping
Isotopes monitored 116Sn, 118Sn, 120Sn
Total analysis time 40min
Spray chamber cooling �3�C
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RESULTS AND DISCUSSION
Chromatograms
In order to provide the best resolution for the five organotin compounds in theshortest analysis time, several stationary phases and column dimensions as well asdifferent mobile phase compositions with attention to the organic solvent (methanoland acetonitrile), ion-pairing reagent, pH value, and flow rate were tested. The bestresults were obtained using a Pursuit 5m-C18 column (250� 4.6mm i.d., VarianTechnologies, USA) with a gradient elution by a mobile phase consisting ofmethanol-10% glacial acetic acid, and the flow rate of mobile phase was 0.50mL �min�1. The pH value of the aqueous phase was adjusted to 3.0 by adding triethyl-amine in10% glacial acetic acid (v=v). Under these conditions selected, thechromatographic separation was achieved in 40min with good resolution as shownin Figure 1.
Linearity and Limits of Detection
The peak area of the five organotins against concentration was linear withgood correlation coefficients of 0.9920–0.9983 over the range of 0.5–100.0 mg �L�1.The limits of detection (LODs) and limits of quantification (LOQs) were evaluated
Table 3. Parameters of multiple reaction monitoring for three organotins with HPLC-MS=MS analysis
Organotin Precursor ion (m=z) Product ion (m=z) Collision energy (V) Fragmentor (V)
DBT 279.2 232.7 6 90
279.2 176.6 6 90
TPhT 351.1 196.9 30 210
351.1 119.8 30 210
TBT 291.2 178.9 10 60
291.2 234.8 10 60
Figure 1. HPLC–ICP–MS chromatogram of standard mixture solution of the five organotins (40mgL�1)
in gradient mobile phase and pH¼ 3.0 (0 to 22min methanol=10% glacial acetic acid 65=35, v=v; 22 to
26min move to methanol=10% glacial acetic acid 85=15, v=v; 26 to 40min methanol=10% glacial acetic
based on a signal-to-noise ratio of 3 and 10, respectively. The results from regressionanalysis performed on calibration curves, LODs, and LOQs are presented in Table 4.
Selection of Extraction Solvent and Method
The n-Hexane and dichloromethane have been often used to extract organotincompounds in liquid samples (Wan et al. 2012; Yu et al. 2009). The pigment wasextracted from the red wines and the yellow wines when dichloromethane was usedas extraction solvent because of its high polarity. In this study, n-hexane was selectedas the extraction solvent. Methods investigated included microwave-assisted extrac-tion (MAE) and liquid–liquid extraction (LLE) and were evaluated. The addition oftropolone (0.02% w=v) into each extracting solution was also investigated in detail.The recoveries of the five organotins extracted in red wine by different methodsare shown in Table 5. Microwave-assisted extraction with n-hexane containing0.02% tropolone (w=v) exhibited higher extraction intensity compared with liquid–liquid extraction. The recoveries of the analytes were better when 0.02% tropolone(w=v) was added to extraction solvent. Consequently, the microwave method withn-hexane containing 0.02% tropolone (w=v) was chosen as the best extraction con-dition. All the trials were made in triplicate.
Optimization of Extraction Conditions
In this study, the effects of three factors (Portet-Koltalo et al. 2008) on orga-notin compounds’ recovery with microwave-assisted extraction were studied andoptimized by a L9(3
4) orthogonal array. Table 6 illustrates factor allocation forthe orthogonal matrix. In the matrix, the letters A, B, and C represent volume ofn-hexane, extraction time, and temperature, respectively. The numbers 1, 2, and 3denote the three different experimental levels.
A 0.5mL aliquot of the standard mixture solutions at 100 mg �L�1 was added to20mL of a red wine sample. For each experimental trial, triplicates were performed.As a result, twenty-seven of the same samples were prepared in this way andextracted according to the orthogonal array design. Table 6 provides the averagerecoveries of the five organotins, as well as the mean effects (k1, k2, and k3) for eachfactor at different levels. The range in k observed with the change in A was 47.75,which was bigger than 6.02 and 20.03 that resulted from the changes in B and C,
Table 4. Calibration curve equation, correlation coefficient, limit of detection, and limit of quantification
for five organotins
Organotins
Calibration curve
equation (mgL�1)
Correlation
coefficient
LODs (S=N¼ 3)
(mgL�1)
LOQs (S=N¼ 10)
(mgL�1)
DMT y¼ 432.74xþ 372.23 0.9920 0.041 0.14
DPhT y¼ 523.31xþ 160.78 0.9967 0.042 0.14
DBT y¼ 598.86xþ 588.81 0.9973 0.049 0.16
TPhT y¼ 600.21xþ 338.47 0.9956 0.033 0.11
TBT y¼ 900.81xþ 331.90 0.9983 0.029 0.097
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respectively. In other words, a significantly influenced k, while B and C had muchweaker influence. Therefore, deduced from the orthogonal array design, the optimalextraction conditions were A3 B2C3, namely extraction volume 20mL, extractiontime 10min, and temperature 100�C.
Validation of the HPLC-ICP-MS Method
To further evaluate the accuracy of the method, recovery experiments per-formed under the optimum conditions were also conducted. One level (50 mg �L�1)of each organotin was added to 20mL wine samples including red wine, white wine,and yellow wine which represent different kinds of matrix. Each sample was mixedthoroughly and extracted. For each addition level, five replicate experiments wereperformed. Before spiked testing, the blank samples were analyzed. If contaminated,
Table 6. Factors and levels of orthogonal test and experiment results (n¼ 3)
Trial no. A=mLa B=minb C=�Cc
Average recovery=%
DMT DPhT DBT TPhT TBT
1 10 5 80 70.60 70.13 56.57 75.37 70.95
2 10 10 100 70.99 72.74 70.96 86.71 79.96
3 10 15 120 72.31 82.32 65.41 65.70 79.41
4 15 5 100 75.37 100.99 69.35 83.47 100.99
5 15 10 120 82.07 112.86 104.71 84.29 74.42
6 15 15 80 71.50 93.36 104.11 75.64 93.36
7 20 5 120 102.06 100.74 117.78 75.86 83.17
8 20 10 80 81.06 85.66 90.19 83.06 81.41
9 20 15 100 71.86 116.18 92.06 74.45 73.34
k1 218.03 250.68 240.59
Optimization level: A3B2C3
k2 265.30 252.22 247.88
k3 265.78 246.20 260.62
R 47.75 6.02 20.03
aFactor A, volume of n-hexane: level 1, 10mL; level 2, 15mL; level 3, 20mL.bFactor B, extraction time: level 1, 5min; level 2, 10min; level 3, 15min.cFactor C, temperature: level 1, 60�C; level 2, 80�C; level 3,100�C.Ki, mean effect of each factor at level i (i¼ 1, 2, 3).
Table 5. Recoveries (%) of five organotins in red wine by different extraction conditions (n¼ 3)
Table 7. Recovery results of five organotin compounds in wine samples (n¼ 5)
Organotins
Red wine Yellow wine White wine
Average recovery
(%) RSD (%)
Average recovery
(%) RSD (%)
Average recovery
(%) RSD (%)
DMT 82.92 4.54 76.73 7.35 100.40 9.43
DPhT 75.26 6.37 65.18 8.52 86.19 7.11
DBT 84.35 3.68 87.95 4.23 80.36 6.56
TPhT 75.12 5.24 71.28 2.56 86.63 3.08
TBT 102.70 5.27 84.89 3.73 83.57 5.48
Table 8. Analytical results of organotin compounds in wine samples (n¼ 5)
Organotins samples
Content (mgL�1)
DMT DPhT DBT TPhT TBT
Red wine-1 NDa ND 0.13� 0.024b 0.19� 0.032 0.14� 0.016
Red wine-2 ND ND ND ND 0.069� 0.003
Red wine-3 0.29� 0.017 ND ND 0.092� 0.008 0.072� 0.005
Red wine-4 ND ND ND 0.087� 0.012 0.062� 0.008
White wine-1 1.14� 0.23 ND ND ND ND
White wine-2 0.98� 0.043 ND ND ND ND
White wine-3 ND ND ND ND ND
White wine-4 ND ND ND ND ND
Yellow wine-1 ND ND ND ND 0.053� 0.006
Yellow wine-2 ND ND ND ND 0.064� 0.004
aND: not detected (<LOD).bData were shown as mean� SD.
Figure 2. Chromatogram of the red wine-1. Peak identification: 1) DBT; 2) TPhT; 3) TBT. (Figure
available in color online.)
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the recoveries were calculated by subtraction of blank samples. The average recov-eries and relative standard deviations from these experiments are given in Table 7.The ranges in the recoveries for the five organotins present in different wine samples
Figure 3. Mass spectra of the dibutyltin dichloride, triphenyltin chloride, and tributyltin chloride in red
wine-1 sample. (Figure available in color online.)
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were as follows: DMT: 76.73% to 100.40%; DPhT: 65.18% to 86.19%; DBT: 80.36%to 87.95%; TPhT: 71.28% to 86.63%; and TBT: 83.57% to 102.70%. The RSDs wereall below 10.0%. The experimental results are satisfactory, which further show thatthe sample preparation method permits the determination of the five organotins indifferent wine samples.
Application of the Developed Method to Wine Samples
Under optimized conditions, the determination of organotin compounds inseveral matrix wine samples was performed. The contents of organotins in fourred wine samples, four white wines, and two yellow wines are listed in Table 8.TBT was detected in the red wine samples and yellow wine samples, whereas noDPhT was present in these samples. DMT was found in the white wine samplespackaged with plastic. Results for organotins determination in samples were from<0.041 to 1.14, <0.042, <0.049 to 0.13, <0.033 to 0.19, and <0.029 to 0.14mg �L�1
for DMT, DPhT, DBT, TPhT, and TBT, respectively. The chromatogram of redwine-1 is shown in Figure 2.
Confirmation of the Organotins in Wine Samples by HPLC-MS/MS
The contents of organotins in the red wine-1 sample extracted by microwave-assisted extraction revealed that the sample contained dibutyltin dichloride, triphe-nyltin chloride, and tributyltin chloride. In order to further confirm these organotins,LC–MS=MS was introduced. In the LC–MS=MS conditions previously descri-bed, three organotins were detected with precursor ion (m=z) and product ion(m=z), and the parameters of multiple reaction monitoring (MRM) for the threeorganotins are shown in detail in Table 3. The corresponding mass spectra(Figure 3) for three organotins (DBT, TPhT, TBT) of the red wine-1 matched thedata of the standards, which further confirmed that the red wine-1 sample containeddibutyltin dichloride, triphenyltin chloride, and tributyltin chloride.
CONCLUSIONS
An approach for the detection of organotin compounds in several matrix winesamples by microwave-assisted extraction coupled with HPLC–ICP-MS wasdeveloped. Low LODs and good validation parameters were achieved for all theanalytes. The best advantage in the proposed method was the matrix in three kindsof wine had no influence on the determination of organotin compounds, becauseother alkyltins had different retention times, and inorganic tin and pigment werenot extracted by n-hexane containing 0.02% tropolone. The extraction conditionswere optimized systematically by orthogonal array, which led to considerable timesavings. The microwave technique coupled with HPLC–ICP-MS provided satisfac-tory recoveries for the determination of DMT, DPhT, DBT, TPhT, and TBT indifferent wine samples. The detection limits of DMT, DPhT, DBT, TPhT, andTBT were 0.041, 0.042, 0.049, 0.033, and 0.029 mg �L�1, respectively. According toEuropean Union (EU) legislation, the maximum residue limits for triphenyltin(TPhT), fenbutatin oxide, and the sum of azocyclotin and cyhexatin (TCT) (EU
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Pesticides Database 2011) in wine grapes were 0.005 to 0.2mg �L�1. The detectionlimits of five organotins were lower than the maximum reside limits, and the methodpreviously established was suitable to monitor organotin compounds in differentwine samples.
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