Determination of Nine Organophosphorus Pesticides in Medicinal Plant Raw Materials by High Resolution HPLC–MS/MS

A procedure is developed for the simultaneous determination of organophosphorus pesticides ( OPP ) diazinon, dimethoate, omethoate, pirimiphos-methyl, pirimiphos-ethyl, malathion, malaoxon, chlorpyrifos-methyl, and fosalone in medicinal plant raw materials using high-resolution liquid chromatography–mass spectrometry. The procedure uses a rapid method of sample preparation by the extraction of crushed plant materials with acetonitrile. The analysis conditions in the reversed-phase chromatography version are optimized. Determination is carried out by the internal standard method using deuterated standards malathion-d6 and dichlorvos-d6 based on the two most intense ionic reactions specific for each individual OPP. The procedure was tested on an example of plant raw materials—valerian ( Rhizomata cum radicibus Valerianae officinalis ) rhizomes and roots and validated according to the specificity, linearity, accuracy, analytical range, limit of quantification, precision, and matrix effect parameters. The proposed procedure can be used to determine the indicated OPP in a wide range of concentrations from 0.01 to 10 000 ng/g of raw materials in medicinal and agricultural plant growing.