Simultaneous and rapid determination of three organophosphorus pesticides from vegetable and cereal samples with a magnetic dispersive solid-phase microextraction method by gas chromatography-mass spectrometry

Abstract

ABSTRACT A straightforward and fast magnetic dispersive solid-phase microextraction method (MDSPME) as a sample preparation procedure coupled with gas chromatography/mass spectroscopy (GC/MS) was developed to measure three organophosphorus pesticides (OPPs), including ethion, diazinon, and chlorpyrifos, from fruit and cereal samples. Magnetic Fe3O4@ reduced graphene oxide nanocomposites as an excellent sorbent were synthesised based on several steps such as graphite oxide preparation, graphite oxide exfoliation, graphene oxide reduction, and chemical co-precipitation of magnetic Fe3O4 methods. Nine factors affected in the MDSPME procedure were thoroughly optimised using the design of experiment approach. The Plackett-Burman design and central composite design were utilised for screening the significant factors and for optimising the factors, respectively. The calibration curves of ethion, diazinon, and chlorpyrifos were linear in the ranges of 0.008–4.5, 0.01–4.0, and 0.01–4.5 ng ml−1 with R-squared of 0.9953, 0.9923, and 0.9981, respectively. The proposed method has high preconcentration factors (PF ≥ 220), low sample solution consumption (5.0 ml), and fast extraction time (5.0 min) for the OPPs determination. Analysis of real samples, including rice and cucumber samples, was shown that the proposed procedure is the suitable sample preparation and determination method for the measurement of OPPs with a recovery percentage in the range of 91.3%-102.2% and RSDs lower than 7.2%. The method has great advantages including low desorption solvent consumption, simple operation, and suitable RSDs for the OPPs determination in the fruit and cereal samples with complex matrices.