Improved Cleanup of Pesticides in Dry, Difficult Matrices Using a Novel Dual-Layer SPE Cartridge for LC/MS/MS and GC/MS/MS Analysis Jennifer Claus, Katherine Stenerson, Olga Shimelis, Michael Ye
A major obstacle in food analysis Dry Samples A recent survey to food analysis customers revealed that 33% have difficulty analyzing compounds in dry commodities. 2
The Problem Dry commodities often produce very dirty QuEChERS extracts Spices Herbs Tea Coffee QuEChERS extract of chili powder QuEChERS extract of turmeric QuEChERS (dspe) cleanup is not sufficient Current dual layer cartridges provide some cleanup but Can be cumbersome to use Reduce recovery of planar pesticides 3
To clean up dry, difficult matrices Novel Dual-Layer SPE Cartridge Dual layer SPE cartridge (1 ml and 3 ml) containing PSA, C18, specialty carbon, and Z-Sep Effectively cleanup difficult matrices prior to pesticide residue analysis Reduces background enough for ppb level detection of pesticides by GC/MS/MS and LC/MS/MS Suitable recoveries for a wide range of pesticides of different polarities and classes were obtained and minimal background interference was noted. 4
To clean up dry, difficult matrices New Dual-Layer SPE Cartridge Top Bed: 120 mg PSA, C18, and Graphsphere 2031 Top Bed: 270 mg PSA, C18, and Graphsphere 2031 Bottom Bed: 100 mg Z-Sep Bottom Bed: 225 mg Z-Sep 5
How does it work? Specialized Carbon (proprietary) Reduces pigmentation and allows for recovery of planar pesticides without toluene Primary-secondary amine (PSA) C18 Removes sugars, organic acids, fatty acids, and polar pigments Removes lipid and fats via hydrophobic interactions Z-Sep sorbent (proprietary) Removes remaining oils and some pigments via Lewis acid Lewis base interactions 6
Application 1: Analysis of Pesticides In Turmeric Powder 2 g turmeric powder + 10 ml water, mix and let stand for 30 min. Add 10 ml of ACN w/1% acetic acid and shake at 2500 rpm for 10 min Add contents of Supel QuE Citrate extraction tube and shake for 1 min Centrifuge at 5000 rpm for 5 min Draw off supernatant Condition: 1 ml Supelclean Ultra SPE Cartridge with 1 ml ACN w/1% acetic acid Cleanup with Supelclean Ultra 2400 GC: 0.1 ml undiluted extract GC: 2 ml ACN w/ 0.5% formic acid Load: Elute: LC: 0.3 ml of extract diluted 5X with ACN w/1% acetic acid LC: 2 ml 80:20 ACN:MeOH w/4 mm NH 4 formate GC: Concentrate to FV 0.5 ml Prepare for analysis: LC: Dilute to FV 10 ml w/water with 5 mm NH 4 formate & 0.1% formic acid 7
Application 1: Analysis of Pesticides In Turmeric Powder For LC For GC LC GC Uncleaned QuEChERS extract Cartridge during use with turmeric extract Turmeric extract after cleanup and prior to conc. or dilution step 8
Application 1: Analysis of Pesticides In Turmeric Powder Pesticide Recoveries for Spiked Turmeric Spiked at 100 ng/g 140% 130% 120% 110% 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 9 %RSD for the sets of spiked replicates, was less than 20% for 44 of the 51 pesticides
Application 1: Analysis of Pesticides In Turmeric Powder GC/MS Scan Analyses of Turmeric Extracts Before Cleanup 0 20000 40000 60000 80000 0 20000 40000 60000 80000 Before cleanup (extract diluted 5X) Total area counts = 2,364,087,358 10 20 30 40 Time (min) After Cleanup with Supelclean Ultra SPE After cleanup (total dilution 5X) Total area counts = 1,875,812,846 10 20 30 40 Time (min) 10
Application 2: Analysis of Pesticides In Green Tea 1) QuEChERS Extraction: 11
Application 2: Analysis of Pesticides In Green Tea 2) Cleanup: SPE QuEChERS 12
Application 2: Analysis of Pesticides In Green Tea LC/MS/MS Analysis Conditions GC/MS/MS Analysis Conditions 13
Dual Layer, multisorbent SPE tube using Zirconia coated Silica Clean up of Green Tea Sample Comparison vs. PSA/C18/GCB (QuEChERS) No Cleanup GC/MS 41 Pesticides @ 2 spike levels (5 ng/g & 50 ng/g) The Dual Layer, Multisorbent tube (Ultra 2400) provided cleaner extracts generally higher recovery at better RSDs. Number of Pesticides with recovery range 70-120% and RSDs <20% Ultra 2400 Spike Multisorbent Tube (Ultra 2400) PSA/C18/GCB (QuEChERS) 5 ng/g 30 8 50 ng/g 38 34 PSA/C18/GCB (QuEChERS) T416109 Pesticides in Green Tea 14
Experimental Conclusions Sorbents in the new dual-layer SPE cartridge provide efficient cleanup of difficult samples such as spices and other dry commodities. Efficient cleanup of this difficult matrices prior to pesticide residue analysis led to Reduced background, sufficient for ppb level detection of pesticides by GC/MS/MS and LC/MS/MS Suitable recoveries for a wide range of pesticides of different polarities and classes from turmeric and green tea extract sigma-aldrich.com/supelcleanultra 15 New Technologies in Sample Prep for Food
Acknowledgments Many Thanks to. Supelclean Ultra Project Team (Bellefonte) Katherine Stenerson Olga Shimelis Michael Ye Lisa DeHaas David Salaske Janice Burger Jeff Thomas Klaus Buckendahl, Technical Marketing R&D, Planning, Intermediates, & Production (Bellefonte) 16
17 Thank You For Your Kind Attention!