Modified QuEChERS sample preparation method and applied for the analysis of 30 pesticide residues in Iran tea in 2020-2021 using gas chromatography-tandem mass spectrometry.

In the present study, the conventional QuEChER (fast, easy, inexpensive, effective, rugged and safe) method was modified and evaluated to measure thirty major pesticide residues in the most widely used teas in Iran. To determine the pesticide residues, gas chromatography-mass spectrometry (GC-MS) was used. The principles of the proposed method are similar to the conventional method, involves acetonitrile-based sample extraction, followed by dispersive solid-phase extraction (D-SPE) using primary-secondary amines (PSA). For the proposed validation, parameters including linearity, selectivity, retrieval, accuracy, precision and uncertainty were evaluated. Under optimal experimental conditions, for thirty analytese, linearity was observed in the range of 0.01-1000.0 µg L^-1 and limits of detection and quantification were in the range of 0.4-1.7 µg respectively. Accuracy in term recovery ranged from 80.66% to 95.66% for 84% and precision in the term relative standard deviations lower than 6.8%. The expanded measurement uncertainty was not higher than 19.07% for all...