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Determination of pesticide residues in high oil vegetal commodities by using various multi-residue methods and clean-ups followed by liquid chromatography tandem mass spectrometry.

Journal of chromatography. A (2013-07-23)
Łukasz Rajski, Ana Lozano, Ana Uclés, Carmen Ferrer, Amadeo R Fernández-Alba
ABSTRACT

Several extraction methods were evaluated in terms of recoveries and extraction precision for 113 pesticides in avocado: QuEChERS with various d-SPE clean-ups (Z-Sep, Z-Sep+, PSA+C18 and silica), miniLuke and ethyl acetate. Extracts were analysed using liquid chromatography coupled with triple quadrupole mass spectrometer working in multi-reaction monitoring mode. Z-Sep and Z-Sep+ are new types of material for high lipid matrices - these two sorbents contain ZrO2, which improves fat removal from the extracts. The QuEChERS protocol with Z-Sep provided the highest number of pesticides with recoveries in the 70-120% range along with the lowest amount of coextracted matrix compounds. Subsequently, this method was validated in two matrices - avocado and almonds. In the validation recoveries at two levels - 10 and 50μg/kg - limit of quantitation, linearity, matrix effects, as well as the inter- and intraday precision were studied. In the avocado samples, 107 analytes had LOQs equal to 10μg/kg (signal to noise of quantitative transition was equal 20 or more). In the almond samples, 92 pesticides had LOQs equal to 10μg/kg (S/N≥20) and 2 pesticides at 50μg/kg. The validated method was employed in the analysis of real avocado and almond samples.

MATERIALS
Product Number
Brand
Product Description

Supelco
Supel QuE, Z-Sep+ Bulk, pkg of 20 g
Supelco
Supel QuE, Z-Sep/C18 Tube, centrifuge tube volume 2 mL, pack of 100
Supelco
Supel QuE, Z-Sep+ with MgSO4 Tube, centrifuge tube volume 12 mL, pack of 50 ea
Supelco
Supel QuE, Z-Sep with MgSO4 Tube, centrifuge tube volume 12 mL, pack of 50 ea
Supelco
Supel QuE, Z-Sep+ Tube, centrifuge tube volume 2 mL, pack of 100 ea
Supelco
Supel QuE, Z-Sep Tube, centrifuge tube volume 2 mL, pack of 100 ea
Supelco
Supel QuE, Z-Sep+ with MgSO4 Tube, centrifuge tube volume 2 mL, pack of 100 ea
Supelco
Supel QuE, Z-Sep with MgSO4 Tube, centrifuge tube volume 2 mL, pack of 100 ea
Supelco
Supel QuE, Z-Sep Bulk
Supelco
Supel QuE, Z-Sep+ Tube, pk of 50, centrifuge tube volume 15 mL , Shaker Compatible
Supelco
Supel QuE, Z-Sep Tube, pk of 50, centrifuge tube volume 15 mL , Shaker Compatible
Supelco
Supel QuE, Z-Sep with MgSO4 Tube, pk of 50, centrifuge tube volume 15 mL , Shaker Compatible
Supelco
Supel QuE, Z-Sep/C18 Tube, pk of 50, centrifuge tube volume 15 mL , Shaker Compatible
Supelco
Supel QuE, Z-Sep+ with MgSO4 Tube, pk of 50, centrifuge tube volume 15 mL , Shaker Compatible