Evaluation of matrix effects of pesticide residues on a multi method for tea, spices and food of animal origin using LC-MS/MS

Brand I., Kroschwald J., Büttner S., Witt G.
Evaluation of matrix effects of pesticide residues on a multi method for tea, spices and food of animal origin using LC-MS/MS
Poster im Rahmen des European Pesticide Residue Workshops (EPRW 2022), 19. – 23.09.2022

Interfering matrix components and coeluting substances can lead to a change in the signal intensity of the analytes during ionization. The matrix effects may cause a signal enhancement or signal suppression (ion suppression). Matrix-matched-calibration or standard addition can be used to compensate these effects, as well as the use of isotopically labeled standards. [1] [2]
In this study, matrix effects of a multi-method for 236 pesticide residues using QuEChERS by LC-MS/MS in complex food matrices and in food of animal origin were evaluated. A broad range of matrices were investigated, such as dry plant products like tea (green, black and peppermint tea), dry herbs (basil, oregano), spices (cumin, coriander seeds, nutmeg) and food of animal origin like feta, egg, milk powder, duck, beef liver and salmon fish. A cumin-coriander-nutmeg-mixture was also tested. Two cleaning materials were compared: enhanced matrix removal-lipid (EMR-lipid) and PSA/C18. The matrix effects were considered by comparing the slope of the solvent calibration to the matrix-matched calibration.
95 % of the analyzed samples from food of animal origin showed negligible matrix effects for both clean-up materials. Significant signal enhancement occured for metaflumizone (ME>120 %) in duck, beef liver and salmon. Signal suppression (ME <50 %) was observed for methamidophos in beef liver. In green tea 86 % of the analytes showed no matrix effects, followed by black tea with 66 % and peppermint tea with 50 %. In herbs like basil and oregano no matrix effects were observed for 50 % of the compounds. Negligible matrix effects in spices were observed for 75 % of the analytes in cumin and coriander seeds, 54 % in nutmeg. A strong ion suppression was detected for pyraclostrobin in nutmeg (ME -60 %). A strong ion suppression was detected for pyraclostrobin in nutmeg (ME -60 %). A strong signal enhancement occured in all investigated spices for metaflumizone (ME >50 %).
In terms of the evaluated matrix effects there were no major differences between the clean-up with PSA/C18 and EMR-lipid.

[1] Kromidas S (Hrsg.) (2017): Das HPLC-MS-Buch für Anwender. WILEY-VCH Verlag Weinheim. ISBN 978-3-527-34291-4.
[2] SANTE 11312/2021 (2022): Guidance document on analytical quality control and method validation procedures for pesticide residues and analysis in food and feed.