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Automation Meets Multi-Residue Pesticide Analysis: An Alternative Workflow for Sample Preparation

7 Mar 2021

Restek has reinvented sample preparation for pesticide residue analysis by LC-MS/MS. A new workflow which enables the automation of sample cleanup has been shown to save time and money over conventional hands-on sample preparation procedures. By leveraging the power of inline sample preparation (ILSP), matrix constituents are removed from sample extracts concomitantly with analysis resulting in unprecedented increases in sample throughput.

Recently, ILSP was put to the test with spinach matrix where 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.