Evaluation of Modified QuEChERS Using Small-Scale SPE for the Analysis of Organophosphorus Pesticides in Spinach.

Abstract

Background: The Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method has been widely applied to various compounds and matrices. However, the clean-up process of QuEChERS with dispersive solid-phase extraction (d-SPE) is considered to be not always sufficient. Therefore, a modified QuEChERS using small-scale SPE (abbreviated as "modified QuEChERS") for the clean-up process has seen an increasing number of users in Japan; it is therefore necessary to evaluate its performance.

Objective: To evaluate the performance of modified QuEChERS for the analysis of nine organophosphorus pesticides (OPPs) in spinach, and to compare the various parameters among modified QuEChERS, QuEChERS, and the Japanese official multiresidue method (JOMM).

Methods: The modified QuEChERS was evaluated by a recovery test using blank spinach samples and quantification using a pesticides-containing quality control spinach sample. A matrix effect was also evaluated for gas chromatography with mass spectrometry (GC/MS) with the stomach-shaped spiral large volume injection (LVI). Various parameters including accuracy, time, cost, and clean-up effect were compared among modified QuEChERS, QuEChERS, and JOMM.

Results: The mean recoveries, the intra-day repeatability, and the inter-day reproducibility for modified QuEChERS were acceptable according to the validation guideline. The concentration of fenitrothion in the pesticides-containing quality control spinach sample obtained by modified QuEChERS was comparable that obtained by QuEChERS and JOMM. It was found that the clean-up of the blank spinach sample by modified QuEChERS using small-scale SPE can be more effective than that by QuEChERS using d-SPE. A matrix effect was newly evaluated in our analysis by GC/MS with the stomach-shaped spiral LVI.

Conclusion: The modified QuEChERS is an accurate and simple method of analyzing OPPs in spinach.

Highlight: The modified QuEChERS is not only accurate but also a fast, cost-effective, and environment-friendly method for analyzing OPPs in spinach.