CHROMTECH GmbH • Buchwiese 3 • D-65510 Idstein, Germany • +49-6126-1686 • www.chromtech.de • 05/2003

Application Note SP303e

Determination of Pesticides in Drinking Water with SPDE-GC/MS

Introduction

In agriculture, pesticides are used extensivelyagainst insects, moulds and weeds. Some pe-sticides are suspected as endocrine dis-ruptors. Due to the good water solubility incombination with the high persistence of somepecticide compounds an increased danger forgroundwater and drinking water exists.The Netherlands National Institute of PublicHealth and Environmental Protection (RIVM,1992) concluded that "groundwater is threate-ned by pesticides in all European states. Thisis obvious both from the available monitoringdata and calculations concerning pesticideload, soil sensitivity and leaching... It has beencalculated that on 65% of all agricultural landthe EC standard for the sum of pesticides(0.5; µ g/l) will be exceeded. In approximately25% of the area this standard will be excee-ded by more than 10 times..."The environmental hazard potential resultingfrom this is kept as low as possible by an ap-propriate legislation. This is the reason whydrinking water must be continually monitoredto determine the trace levels of these pestici-des.Regardless of the analytical detection method(UV, MS, ECD,...), the quantitation of pestici-des in drinking water requires extraction andenrichment of the sample to minimize matrixrelated problems. Therefore the determinationof pesticides in drinking water close to thedetection limit requires appropriate analyticalequipment.

Due to the combination of fully automatedCHROMTECH SPDE-Option followed bymass spectrometric detection (SPDE-GC/MS)

the determination of pesticides in water downthe low ppt range is possible in routine analy-sis.

In this application note we report the suitabilityof SPDE-GC/MS with pesticide spiked drin-king water.

Methods

GC-Conditions: Agilent 6890N. Co-lumn:Varian VF-5MS, 30 m x 0.25 mm x 0.25µm. 70°C (1 min), 15°C/min ⇒ 320°C (10min). S/SL-Injector (250°C), 1 min splitless, 30mL/min Purge Flow. Helium (1,2 mL/min).MS-Conditions: KODIAK 1500 with GC In-terface (280° C). EI at -70 eV, 150 µA,230° C. SIM with 300 ms Scan time and 0.7 uSIM Width; 1250 amu/sec.SPDE-Conditions: CHROMTECH SMM (Sin-gle Magnet Mixer) on CTC CombiPAL. 20 mlHeadspace vials; Temperature (Syringe andOven): 50° C; 500 rpm Agitator Speed; 40 mmSample Penetration; 90 Extraktion Strokes à 1ml; 1 ml Desorption Gas Volume with 50 µL/sFlow Speed; 60 s Pre Desorption Time

Results and Discussion

Figure. 1 shows the total ion current (TIC) ofthe Pesticide Mix (2.5 ppm) scanned fromm/z 50-550. The performed scan was used foridentification of the pesticides and thedetermination of their retention times.Table 1 illustrates the retention times of theanalytes and the respective SIM ions thatwere used for the following analyses.

TM

CHROMTECH GmbH • Buchwiese 3 • D-65510 Idstein, Germany • +49-6126-1686 • www.chromtech.de • 05/2003

Table 1Nr. Name RT SIM Ion SIM

(min) (m/z) Group

1 α-Lindane 13.66 219 12 β-Lindane 14.01 219 13 χ-Lindane 14.14 219 14 δ-Lindane 14.53 219 15 Heptachlor 15.15 100 26 Aldrin 15.66 66 37 Heptachlorepoxide 16.17 81 48 Endosulfan I 16.67 195 59 o,p-DDE 16.87 176 610 Dieldrin 17.03 79 611 Endrin 17.31 81 712 o,p-DDD 17.42 235 713 Endosulfan II 17.44 235 714 Endrin aldehyde 17.63 67 815 o,p-DDT 17.91 387 816 Methoxychlor* 18.56 227 9

* Methoxychlor has the fourfold amount in all mentioned standards anddilutions.

The following illustrations 3 to 6 represent ineach case the TIC of the SIM traces, with de-creasing concentrations of the standard Pesti-cide Mix. The number of piston strokes of theSPDE syringe during the extraction was al-ways 90 strokes. The spiked water sampleswere agitated during the extraction with a ma-gnetic stir bar at 500 rpm.

Abb. 1: TIC (m/z 50-550) of the Pesticide Mix (2.5 ppm)

Abb.3: TIC of the SIM traces (comp.Tab.1); 25 ppb (µg/L),90 srokes, agitated; PDMS/AC.

1

2

3

4

5

6

7

89

10

11

12/13

14

15

16

Abb. 2: Principle of the automated SPDE extraction. Theanalyte is enriched by controlled pumping through thespecially coated syringe needle.

Gasflow

Syringwithneedlecoatedinside

liquid sample headspace sample

HotInjector

GCColumn

Extraction of Liquid or Headspace samples Desorption into hot Injector

CHROMTECH GmbH • Buchwiese 3 • D-65510 Idstein, Germany • +49-6126-1686 • www.chromtech.de • 05/2003

The presented results show very clearly thatidentification and quantitation of pesticides ispossible in drinking water by means of SPDE-GC/MS even in the ppt range. The SPDEtechnique is characterised by complete auto-mation and highest sensitivity. Compared toother extraction procedures only a smallquantity of sample (10-20 mL water) and notoxic solvent is needed. The system is basedon the CTC CombiPAL sampler, so no furtherlaboratory space is needed. Due to the abovementioned advantages SPDE could be themethod of the choice for the routine analysisof these pesticides in water.

Abb.5: TIC of the SIM traces (comp.Tab.1); 25 ppt (ng/L),90 strokes, agitated; PDMS/AC.

1

2

3

45

6

7

89

10

11

12/13

14

15

16

Abb.6: TIC of the SIM traces (comp.Tab.1); 2.5 ppt (ng/L),90 strokes, agitated; PDMS/AC.

1

2

3

4 5

6

7

8

9

10

1112/13

1415

16

Abb.4: TIC of the SIM traces (comp.Tab.1); 2.5 ppb (µg/L),90 strokes, agitated; PDMS/AC.

1

23

4

5

6

7

8

10

11

12/13

14

15

16

9