Methods for Increased Sample Throughput with Dirty Samples

Transcription

1 Methods for Increased Sample Throughput with Dirty Samples Alan D Broske, Limian Zhao, and William H. Wilson Agilent Technologies, Inc. 1

2 Introduction GC inlet liner impacts sample transfer to the GC column Limit matrix deposition in selected areas of the liner Matrix impurities decompose chemical deactivation Matrix impurities reach the analytical column Solution with liner design and deactivation that are unique for the type of injection Efficient spreading of matrix impurities over liner surface A more stable deactivation layer Use well deactivated glass wool to trap impurities Agilent s Ultra Inert liner deactivation process significantly improves the efficiency and robustness of the glass liner and glass wool deactivation Quantitative analysis of pesticides Reduced matrix interference 2

3 Liners Used Inlet liners used in this evaluation include Dimpled liner (2 mm ID) Single taper (4 mm ID) Single taper with wool (4 mm ID) Dimple (Agilent p/n ) Single Taper (Agilent p/n ) Single Taper with Wool (Agilent p/n ) 3

4 Experimental Analysis of pesticides by GC/ECD Instrument conditions Agilent GC/ECD system, equipped with Agilent 7683B Autosampler Inlet: S/SL inlet using splitless 250 C, purge time at 0.75 min,1 μl injection volume Inlet liner: Ultra Inert single taper splitless liner (Agilent p/n ) Carrier: He, constant flow, 0.9 ml/min (31 cm/sec) Column: HP-5ms UI, 15 m x 0.25 mm, 0.25 μm (Agilent p/n 19091S-431 UI) Oven: 120 C (1 min), 30 C/min to 220 C, 8 C/min to 280 C (1 min) ECD: 280 C, N makeup, constant column + makeup Sample Endin/DDT sample in MtBE 4

5 Experimental Analysis of pesticides by GC/MS/MS Instrument conditions 300 C, Quad (Q1 & 150 C Data acquisition: Agilent 7890A/7000 GC/MS/MS system, equipped with Agilent 7693 Autosampler Cold Injection: MMI inlet, 60 C (0.1), 700 C/min to C300 C (19). Hot Injection: MMI inlet, splitless in pulsed splitless 280 C, purge flow 50 ml/min at 1 min, pulsed pressure 36 psi for 1 min 1 μl injection volume Inlet liner: Cold: 2 mm Dimpled liner (Agilent p/n ) Hot: Ultra Inert single taper splitless liner with wool (Agilent p/n ) Carrier: Cold: He, psi, constant flow Hot: He, constant pressure, RT locked with min 5

6 Experimental Analysis of pesticides by GC/MS/MS (continued) Instrument conditions Analytical column: HP-5ms UI, 15 m x 0.25 mm, 0.25 μm (Agilent p/n UI) Purged Ultimate Union (Agilent p/n G ) for backflushing Restrictor: Inert Fused Silica tubing, 0.65 m x 0.15 mm (Agilent p/n ) Oven profile: Cold: 60 C (1), 50 C/min to 150 C, then 16 C/min to 200 C, then 7 C/min to 300 C Hot: 100 C (2 min), 50 C/min to 150 C, 6 C/min to 200 C at 16 C/min to 280 C (6 min) Postrun backflush: C, backflush 75 psi, inlet 1 psi during backflush MSD: Transfer 280 C MRM 6

7 Experimental Analysis of pesticides by GC/MS/MS (continued) Sample Representative and active pesticides, 5 ng/ml to 500 ng/ml six points calibration standards, 50 ng/ml QC Matrix Sample Five different fruits and vegetables matrix mixture: flower, banana, strawberry, pear, and lettuce Blank matrices sample were extracted following QuEChERS AOAC method (sample extraction and following dispersive-spe clean up) Agilent Bond Elut QuEChERS AOAC extraction (Agilent p/n ) and dispersive SPE kit for general fruits and vegetables (Agilent p/n ) 7

8 Results and Discussion Ultra Inert liners are highly deactivated as evidenced by low endrin/ddt breakdown (Hot splitless/ecd) Endrin breakdown results from active sites on liner. DDT breakdown comes from the metal inlet parts. Multiple injections can decompose the liner deactivation and increase breakdown. 8

9 Results and Discussion Summary of pesticide breakdown on Ultra Inert and competitive liners after multiple injections Endrin Breakdown (%) DDT Breakdown (%) Injection 1 Injection 50 Injection 100 Injection 1 Injection 50 Injection 100 UI Lot UI Lot UI Lot Vendor Vendor Ultra Inert liners show low breakdown even after 100 injections demonstrating high deactivation stability. Some competitive liners show high breakdown and short lifetime. 9

10 Results and Discussion Ultra Inert liners are highly deactivated as evidenced by high recoveries of pesticides (Hot splitless/ms/ms) MRM of 10 ng/ml pesticide sample 1. Methamidophos 2. Dichlorvos 3. Mevinphos 4. Acephate 5.?-Phenylphenol 6. Omenthoate 7. Dimenthoate 8. Altrazine 9. Lindane 10. Diazinon 11. Chlorothalonil 12. Chloropyrifos methyl 13. Vinclozolin 14. Carbaryl 15. Tolclofos methyl 16. Dichlorfluanid 17. Aldrin 18. Malathion 19. Dichlorobenzophenone 20. Pirimiphos ethyl 21. Tolyfluanid 22. Procymidone 23. Endrin 24. Ethion 25. Endosulfan sulfate 26. DDT 27. Endrin ketone 28. Iprodione 29. Phosmet 30. Phosalone 31. Permethrin isomers 32. Coumaphos 33. Deltamethrin isomers The liner to liner performance reproducibility was tested with replicates of six Ultra Inert liners with wool from three different pesticides applications. Groups of 12 pesticides were selected as representative analytes. 10

11 Results and Discussion Repeatability: RSD (%) for analytes RF values of 50 ng/ml standard injections Pesticides (peak #) In reagent solvent Ultra Inert liners w/ wool by 100 injections (# liners = 5) Ultra Inert liners w/ wool by 50 injections (# liners = 7) In fruits and vegetables QuEChERS extract Ultra Inert liners w/ wool by 100 injections (# liners = 7) Helix liners by 50 injections (# liners = 3) Methamidophos (1) Acephate (4) Omenthoate (6) Chlorothalonil (11) Chlorothalonil (11) Carbaryl (14) Dichlorfluanid (16) Tolylfluanid (21) Endrin (23) Endosulfan sulfate (25) DDT (26) Endrin ketone (27) Iprodione (28) Phosmet (29) Excellent liner to liner reproducibility achieved by Agilent Ultra Inert liners with wool. 11

12 Results and Discussion Ultra Inert liners with wool generate higher responses for active compounds Pesticides Agilent Ultra Inert liner with wool Helix liner Methamidophos Acephate Omenthoate Dimenthoate Dimpled liners are highly deactivated as evidenced by high recoveries of pesticides with more uniform sample spreading (Cold splitless/ms/ms). 12

13 Results and Discussion (continued) 50 Matrix Runs 100 Matrix Runs The inner diameter was reduced and flow path obstructed preventing matrix from reaching column. Sample directed to liner wall for more uniform spreading and longer lifetime. 13

14 Results and Discussion (continued) Calculated RSD for response factors of selected pesticides at 50 ppb. Performance goal is < 20%. Multiple liner lots shown (red is Helix liner). 14

15 Conclusion The Ultra Inert deactivation shows high stability and provides long lifetime Superior linearity for active pesticides with matrix impurities Consistent liner to liner (lot to lot) reproducibility Unique liner designs for temperature sensitive compounds with extended lifetimes Equivalent or superior to other equivalent liners or popular liners used in the demonstrated applications 15