Automated Inline Pigment Removal for the Analysis of Pesticide Residues in Spinach by Liquid Chromatography Tandem Mass Spectrometry

Author(s): Sharon A. Lupo, Randall L. Romesberg, Xiaoning Lu
Restek Corporation

Published By: Journal of Chromatography A

Year of Publication: 2020


Abstract: An automated inline sample preparation (ILSP) method has been developed for pesticide residue analysis in spinach by LC-MS/MS. Chlorophyll pigments and other matrix constituents were removed from the sample extract using a UHPLC system equipped with an auxiliary pump, 6-port high pressure switching valve, and dual-directional ILSP cartridge containing bonded silica. The new procedure was evaluated as an entirely separate workflow using a simple solid-liquid extraction and as part of a cleanup strategy in conjunction with QuEChERS. Accuracy and precision experiments were conducted in spinach at two concentration levels (n=6). Of the 63 pesticides tested, 86% (0.005 mg/kg) and 100% (0.05 mg/kg) displayed average recoveries within 70-120% and RSD values ≤20% for the ILSP method. In addition, low to moderate matrix effects (<50%) were calculated for 95% of the analytes. Overall performance of the proposed method was found to be better or comparable to a traditional QuEChERS procedure utilizing AOAC formulated salts and dSPE sorbents, while significantly reducing the amount of pigments reaching the MS source. The ILSP workflow is a simpler procedure with fewer steps that require less time than traditional extraction and cleanup techniques.