Pesticide Analysis in Food: Dispersive SPE (QuEChERS method) & HPLC/MS. Dr. Frank Michel

Transcription

1 Pesticide Analysis in Food: Dispersive SPE (QuEChERS method) & HPLC/MS Dr. Frank Michel

2 Pesticides in Food Pesticides in fruit vegetable further food & feeding 2

3 Challenges in pesticide analysis: Various different matrices Fruit & vegetable Acidic/basic High/low water content High/low sugar content High/low starch or protein content High/low fat content Herbs, tea, spices, honey, 3

4 Market: Pesticides Finnland 140 Netherlands 234 Germany 250 Belgium 306 Italy 396 France 435 Spain 486 In all EU 800 World wide >

5 Full Variety of Pesticides Amino acids -5-1 (ph dependant) Flavonoides/Anthocyanes 0 6 Fatty acids Phytosterols Sugars -5-2 Streptomycin -7.5 Glyphosate -4 Quat-P Acidic P. (~40) ph dependant Basic P. ph dependant Phthalate Pyrethroide-P. (~45) Organochlorine-P. (~20) Urea-P. (~30) Organophosphor-P. (~95) Carbamate-P. (~30) PAHs PCBs PBDEs Vit. E 11.5 Carotenoides Chlorphyll log K OW

6 Full Variety of Pesticides Amino acids -5-1 (ph dependant) Sugars -5-2 Streptomycin -7.5 Glyphosate -4 Quat-P Acidic P. (~40) ph dependant Basic P. ph dependant Flavonoides/Anthocyanes Fatty acids Phytosterols GPC/Silica GPC/Silica GPC Phthalate Pyrethroide-P. (~45) Organochlorine-P. (~20) Urea-P. (~30) Organophosphor-P. (~95) Carbamate-P. (~30) PAHs PCBs PBDEs Vit. E GPC 11.5 Carotenoides GPC Chlorphyll GPC log K OW

7 Pesticides in fruit & vegetable former methods Homogenization Extraction Purification Gas chromatography 7

8 Pesticides in fruit & vegetable former methods 10 years ago... Liquid Extraction with dichloromethane followed by gel chromatography and fractionation by silica SPE 8

9 Pesticides in fruit & vegetable former methods From 2004: Accelerated Solvent Extraction (ASE, e.g. Dionex) Gel chromatography GC/MS Analysis Additional work-up for LC-MS/MS 9

10 Full Variety of Pesticides Amino acids -5-1 (ph dependant) Sugars -5-2 Streptomycin -7.5 Glyphosate -4 Quat-P Acidic P. (~40) ph dependant Basic P. ph dependant Flavonoides/Anthocyanes Fatty acids Phytosterols GPC/Silica GPC/Silica GPC GC only after Derivatization GC issues Phthalate Pyrethroide-P. (~45) GPC Organochlorine-P. (~20) Urea-P. (~30) Organophosphor-P. (~95) Carbamate-P. (~30) GC issues GPC Silica PAHs PCBs PBDEs Vit. E GPC 11.5 Carotenoides GPC Chlorphyll GPC log K OW

11 Full Variety of Pesticides Amino acids -5-1 (ph dependant) Sugars -5-2 Streptomycin -7.5 Glyphosate -4 Quat-P Acidic P. (~40) ph dependant Basic P. ph dependant Flavonoides/Anthocyanes Fatty acids Phytosterols GPC/Silica GPC/Silica GPC GC only after Derivatization GC issues Phthalate Pyrethroide-P. (~45) GPC Organochlorine-P. (~20) Urea-P. (~30) Organophosphor-P. (~95) Carbamate-P. (~30) GC issues GPC Silica PAHs PCBs PBDEs Vit. E GPC 11.5 Carotenoides GPC Chlorphyll GPC log K OW

12 QuEChERS Method: dispersive SPE Quick Easy Cheap Effective Rugged Safe M. Anastassiades, S. Lehotay et al., J. AOAC Int. 86 (2) ,

13 QuEChERS Method: dispersive SPE LCGC North America, Jul 1,

14 How does the QuEChERS method work? Homogenize Frozen Samples Addition of solid CO 2 14

15 How does the QuEChERS method work? Extraction Weigh in 10 g sample into a 50 ml centrifuge tube with screw cap Shake 1 min virigously Add 10 ml Acetonitrile & 100 µl Internal Standard (* for samples with high fat content IS should be added after phase separation) 15

16 How does the QuEChERS method work? Add magnesium sulfate, and buffer salt Shake 1 min virigously EN Buffer: Trisodium citrat dihydrate; disodium hydrogencitrate sesquihydrate, sodium chloride AOAC Buffer: Na Acetate Important: First sample in the vial then add salts to prevent lumping of salts. Shake immediately. 18

17 How does the QuEChERS method work? 5 min centrifugation If needed: take 1 ml raw extract for acidic pesticides Acetonitrile phase (to be used for further analysis) Organic Precipitate Water from the sample Salts 19

18 How does the QuEChERS method work? Transfer acetonitrile phase to a centrifuge tube with magnesium sulfate and PSA (Primary Secondary Amine). 25 mg PSA mg MgSO 4 per ml extract. Requirements for colored or fat-containing samples: Add GCB for heavily pigmented samples. Add C18, Z-Sep/C18 or Z-Sep+ for lipid containing samples. Shake! Purification 20

19 QuEChERS Method: Sample Clean-up based around PSA adsorbent PSA - Primary Secondary Amine two pk a [10.1 and 10.9] Better interaction due to two pk a values Removal of fatty acids organic acids polar pigments sugars Also available in tubes 21

20 QuEChERS Method: Sample Clean-up for pigmented or fat-rich samples Pigmented samples: ENVI-Carb selectively removes chlorophyll and carotenoids Fat-containing samples: Freezing out of the fat C18 SPE adsorbent removes the fat Supel QuE Z-Sep/C18 (Discovery DSC-18 + Z-Sep) for samples containing <15% fat Supel QuE Z-Sep+ (C18 and zirconia dual bonded to silica) for samples containing >15% fat 22

21 What are Supel QuE Z-Sep/C18 and Z-Sep+? The Zr atom on the particle acts as a Lewis acid The phosphate groups on the phospholipids are strong Lewis bases and complex with the zirconium atoms Analytes are elute free of phospholipids Diminishes fatty matrix interferences Removes various colors, specifically green pigments Proprietary HybridSPE zirconia-coated silica Phospholipids 23

22 Comparison of sorbents for retention of model fatty compounds oleins. 25 mg of sorbent mixed with 1 ml of olein solution in acetonitrile (400mg/mL total concentration). The remaining oleins were quantified by LC- ELSD and retention was calculated. 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Z-Sep+ Z-Sep/C18 C18 PSA NH2 alumina LRA Silica 24

23 Pesticides in olives 38 pesticides tested in canned olives Selected results are shown in the Figure Recoveries for most pesticides are similar between 2 methods Better recoveries for some pesticides observed using Z- Sep/C18 Fenhexamide (no ion suppression for Z-Sep/C18) Anilazine (no ion suppression for Z-Sep/C18) Sethoxydim (no ion suppression for Z-Sep/C18) C18/PSA Z-Sep/C18 PSA FENHEXAMID ANILAZINE SETHOXYDIM SPIROMESIFEN PHOSMET 26

24 How does the QuEChERS method work? 5 min centrifugation Acidify with 5 % formic acid to ph 5 Use the clear supernatant for chromatography 27

25 How does the QuEChERS method work? Weigh in 10 g sample Add 10 ml Acetonitrile Add Internal Standard Shake Add 4 g MgSO 4 and 1 g NaCl, adjust to ph 5-5,5 with citrate buffer Shake & centrifuge Add MgSO 4 and PSA/(GCB) to aliquot Shake & centrifuge Acidify extract to ph ~ 5 Option: Acidic pesticides LC-MSMS Option: Acid labile pesticides LC-MSMS GC-MSD and LC-MSMS 28

26 QuEChERS method: issues to consider Homogenization with dry ice Extraction: ph adjustment to 5 5,5 (add NaOH, if needed) Aliquot for acidic pestides before PSA addition GCB for coloured samples (chlorophyll, carotenoids) C18, Z-Sep/C18 or Z-Sep+ for lipid containing samples Aliquot for acid labile pesticides before acidification Acidification of purified extract to ph = 5 For GC: use of a PTV (and automated liner exchange) Samples with low water content (< 80 %) e.g. grain, honey, tea, herbs, spices and dried fruit 29

27 QuEChERS method: EU and US EN 15662:2008 Foods of plant origin Determination of pesticide residues using GC-MS and/or LC- MS/MS following acetonitrile extraction/ partitioning and cleanup by dispersive SPE QuEChERS-method AOAC Official Method Pesticide Residues in Foods by Acetonitrile Extraction and Partitioning with Magnesium Sulfate. LCGC North America, Jul 1,

28 QuEChERS Validation in BLAPS AG 2005 W ie d e rfin d u n g S ta n d a rd a b w e ic h u n g W irk sto ff Gurke 0,1 Gurke 0,01 Zitrone 0,1 Zitrone 0,01 Mehl 0,1 Mehl 0,01 Rosine 0,1 Rosine 0,01 Gurke 0,1 Gurke 0,01 Zitrone 0,1 Zitrone 0,01 Mehl 0,1 Mehl 0,01 Rosine 0,1 W irk sto ffe m it a llg e m e in g u te r W ie d e rfin d u n g u n d P rä zisio n 3,4,5 -Trim eth acarb 10 0 % 98 % 95 % 98 % 99% 102 % 98% 1 01% 4 % 6 % 2 % 6 % 4 % 10% 4 % A cep h ate 8 8 % 9 2 % 8 9 % 9 2 % 8 1 % 8 1 % 8 1 % 8 2 % 8 % 1 2 % 1 2 % 1 2 % 5 % 1 3 % 7 % A ld icarb 9 2 % 9 7 % % 9 7 % 9 8 % % 9 7 % % 1 2 % 5 % 5 % 5 % 4 % 6 % 4 % A zoxystrobin 10 0 % 96 % 95 % 96 % 99% 97% 99% 1 00% 5 % 4 % 3 % 4 % 1 % 7 % 4 % B en d iocarb 9 8 % % % % 9 8 % % % 9 8 % 5 % 7 % 4 % 7 % 3 % 4 % 3 % B u toc oxim 8 9 % 8 1 % 9 7 % 8 1 % 9 6 % 9 7 % 9 6 % 9 6 % 2 0 % 4 7 % 5 % 4 7 % 6 % 1 3 % 4 % C a ryl % % % % % % 9 9 % 9 9 % 4 % 8 % 7 % 8 % 7 % 1 1 % 6 % C arbendazimmean recovery 94 % 95 % 90 % in 95 % 587% labs, 88% 84% all 86% analytes 4 % 5 % 3 % 5 % 3 % 4 % 9 % C arbofuran 10 1 % 98 % 101 % 98 % 97% 104 % 98% 98% 4 % 6 % 13 % 6 % 3 % 12% 5 % C yprodinil 99 % 97 % 97 % 97 % 97% 95% 98% 95% 5 % 9 % 3 % 9 % 6 % 7 % 4 % D im e th oa t % % 9 8 % % 9 8 % 9 9 % 9 4 % 9 3 % 4 % 4 % 4 % 4 % 1 % 2 % 5 % Fenhexam id 81 % 83 % 95 % 83 % 83% 77% 81% 83% 17 % 16 % 3 % 16 % 16 % 7 % 14% F en oxycarb % 9 8 % % 9 8 % 9 6 % % % % 4 % 8 % 8 % 8 % 1 % 8 % 3 % F en p rop im orp h 9 8 % 9 6 % % 9 6 % 9 8 % % 9 9 % % 4 % 5 % 7 % 5 % 6 % 1 0 % 6 % F lu fen oxu ron % % 9 5 % % 9 9 % % % % 3 % 1 % 2 0 % 1 1 % 6 % 8 % 5 % Im azalil 77 % 82 % 95 % 82 % 94% 102 % 87% 94% 32 % 19 % 3 % 19 % 3 % 18% 11% Im idaclop rid 96 % 99 % 98 % 99 % 95% 0,01 90% mg/kg 95% 90% 30,1 % 10 % mg/kg 6 % 10 % 3 % 17% 5 % In d oxacarb % 9 6 % % 9 6 % 9 4 % % 9 2 % 1 7 % % 1 0 % 9 % 3 % 1 7 % Ip rovalicarb 10 0 % 10 0 % 101 % 100 % 100 % 98% 98% 1 03% 2 % 4 7 % 4 % 5 % 6 % 5 % Isoproturon 97 % 96 % 98 % 96 % 97% 97% 98% 99% 5 % 17 4 % 17 % 2 % 5 % 4 % L in u ro n Cucumber % 9 8 % 9 9 % 9 8 % % 9 8 % 9 8 % % 697 % 1 1 % 4 % 1 1 % 1 % 6 % 5 % M etalaxyl 10 1 % 10 0 % 100 % 100 % 99% 107 % 99% 97% 6 % 9 % 7 % 9 % 2 % 17% 3 % M eth a m id op h os 9 0 % 9 2 % 8 1 % 9 2 % 7 6 % % 9 1 % 9 % % 9 % 2 3 % 2 3 % 2 0 % M ethiocarb 97 % 94 % 95 % 94 % 89% 92% 93% 95% 6 % 9 11 % 9 % 8 % 8 % 12% M eth o m yl 9 9 % % 9 6 % % 9 4 % % 9 7 % 3 % % 1 1 % 9 % 7 % 5 % M eth o xyfe n ozlemon id 9 8 % 9 6 % 9 9 % 9 6 % % 1 0% % % 598 % 8 % 4 % 8 % 2 % 9 % 5 % M etolach lor % 9 7 % % 9 7 % % % % 2 % 5 4 % 5 % 2 % 7 % 3 % M onocrotoph os 96 % 93 % 95 % 93 % 92% 97% 94% 92% 3 % 7 8 % 7 % 5 % 7 % 6 % O xam yl % 9 4 % 9 5 % 9 4 % 9 8 % % % 4 % % 1 3 % 8 % 2 1 % 6 % O xydem eton -m Wheat ethyl 94 % 97 % 94 % 97 % 90% 96 95% % 87% 86% 595 % 11 % 9 % 11 % 4 % 15% 6 % P icoxystro b in % 9 8 % % 9 8 % % % % 3 % 6 7 % 6 % 3 % 8 % 5 % P irim icarb 9 2 % 9 3 % 9 6 % 9 3 % 9 8 % % 9 5 % 1 0 % 7 2 % 7 % 3 % 6 % 5 % P rom ecarb 9 9 % 9 6 % 9 6 % 9 6 % 9 9 % % % 5 % 5 6 % 5 % 2 % 9 % 2 % P rop a m o carbraisin 9 4 % % 8 8 % % % 1 1% % 8 4 % % 1 6 % 7 % 1 6 % 5 % 3 8 % 1 0 % P ropoxur 10 0 % 10 2 % 98 % 102 % 97% 95% 96% 94% 5 % 3 % 2 % 3 % 2 % 4 % 6 % P yrac lostrob in 9 9 % % 9 8 % % 9 7 % % % % 5 % 5 % 5 % 5 % 3 % 9 % 4 % P yrim ethanil 98 % 96 % 96 % 96 % 95% 95% 97% 96% 3 % 5 % 2 % 5 % 1 % 7 % 4 % S piroxam ine 96 % 95 % 96 % 95 % 96% 99% 96% 99% 6 % 8 % 5 % 8 % 4 % 7 % 5 % Tebuconazol 99 % 99 % 100 % 99 % 97% 106 % 97% 1 01% 4 % 6 % 5 % 6 % 8 % 15% 6 % Te b u fen o zid % % 9 8 % % 9 7 % % % % 4 % 5 % 4 % 5 % 2 % 5 % 4 % Th iab en d azol 9 4 % 9 9 % 9 1 % 9 9 % 8 8 % 9 1 % 8 5 % 8 4 % 6 % 4 % 4 % 4 % 4 % 6 % 1 5 % Th iac lop rid % 9 5 % % 9 5 % 9 8 % % 9 6 % % 4 % 6 % 1 1 % 6 % 5 % 8 % 5 % Th iofanox 89 % 88 % 99 % 88 % 96% 83% 87% 85% 31 % 13 % 2 % 13 % 6 % 33% 10% V am id oth ion 9 8 % 9 6 % 9 6 % 9 6 % 9 6 % 9 6 % 9 3 % 9 1 % 5 % 6 % 1 0 % 6 % 5 % 4 % 9 % 2 W irk s to ffe m it z.t. s c h le c h te r W ie d e rfin d u n g w e g e n Z e rse tzu n g Sulfonyl urea compounds E thiofencarb 59 % 67 % 95 % 67 % 91% 90% 85% 90% 45 % 29 % 6 % 29 % 8 % 20% 21% P ym e troz in 6 7 % 6 9 % 4 8 % 6 9 % 5 7 % 6 0 % 3 7 % 4 3 % 1 3 % 2 5 % 2 5 % 2 5 % 9 % 7 % 4 8 % 4 W irk sto ffe m it s c h le c h te r W ie d e rfin d u n g w e g e n Z e rse tzu n g, d a E x tra k t a n g e sä u e rt C inosulfu ron 62 % 63 % 79 % 63 % 43% 42% 46% 47% 33 % 30 % 12 % 30 % 70 % 75% 58% M etsu lfu ron -m eth yl 6 3 % 6 4 % 6 9 % 6 4 % 4 2 % 3 7 % 4 7 % 5 2 % 2 9 % 3 0 % 1 6 % 3 0 % 7 0 % % 4 5 % P rosu lfu ro n 7 1 % 6 9 % 7 8 % 6 9 % 4 8 % 4 4 % 5 2 % 4 8 % 2 7 % 2 3 % 8 % 2 3 % 5 0 % 6 0 % 5 2 % Th ifen sulfuron -m ethyl 65 % 65 % 69 % 65 % 40% 32% 46% 40% 34 % 30 % 17 % 30 % 85 % 1 05% 74% 32 Bund-Länder-Arbeitsgruppe Pflanzenschutz- u. Schädlingsbekämpfungsmittel

29 Benefits of the QuEChERS method Fast (8 samples in 30 min instead of 1,5 days) Easy (no elaborate steps) Cheap (centrifuge is only equipment needed) Low amounts of solvents needed (10 ml acetonitrile) Minor use of glass ware Quick, Easy, Cheap, Effective, Rugged, Safe QuEChERS 33

30 The only drawback Work-up takes approx. 30 min. Weighing the salts and SPE material is most tedious Pre-weighed sorbents and salts save work and time High-purity reagents from Sigma-Aldrich Convenient and reliable 34

31 Ready-to-use products for QuEChERS for EN 15662:2008 Prod. Nr. Description Content Pack size Tube volume magnesium sulfate, 4 g U Supel QuE Citrate Extraction Tube sodium chloride, 1 g sodium citrate dibasic x 1,5 H 2 O, 0.5 g sodium citrate tribasic x 2 H 2 O, 1 g pk of 50 12mL U U U U Supel QuE PSA Tube Supel QuE PSA/C18 Tube Supel QuE PSA/ENVI-Carb Tube 1 Supel QuE PSA/ENVI-Carb Tube 2 Supelclean PSA, 150 mg magnesium sulfate, 900 mg Discovery DSC-18, 150 mg Supelclean PSA, 150 mg magnesium sulfate, 900 mg Supelclean ENVI-Carb, 15 mg Supelclean PSA, 150 mg magnesium sulfate, 900 mg Supelclean ENVI-Carb, 45 mg Supelclean PSA, 150 mg magnesium sulfate, 900 mg pk of 50 pk of 50 pk of 50 pk of 50 12mL 12mL 12mL 12mL U Supel QuE Empty Tube 50 ml pk of ml U Supel QuE Z-Sep/C18 Tube pk/ U Supel QuE Z-Sep+ Tube pk/50 35

32 QuEChERS Method - a Mini-Multi-Method Routine investigation of an extract for hundreds of pesticides by different analytical method. GC MSD EI (3 x), NCI ECD (2 Calibr.) LC MSMS pos. und neg. MS (trap) 37

33 More information on QuEChERS General: sigma-aldrich.com/quechers quechers.com Custom QuEChERS tubes sigma-aldrich.com/custom-quechers Reporter article Intralab Validation QuEChERS/HPLC Reporter QuEChERS-HPLC Reporter article Pesticides from Oranges by GC/MS Reporter QuEChERS-GC 43

34 More information on QuEChERS 44

35 Dziękuję za uwagę! 45