[Validation of a Method for the Simultaneous Determination of Pesticide Residues in Soybeans and Brown Rice by...

A method for the simultaneous determination of pesticide residues in soybeans and brown rice was developed using GC-MS/MS with a SPE-based sample preparation procedure. Samples were extracted according to the official method of the Ministry of Health, Labour and Welfare (MHLW) of Japan, followed by pH adjustment, salting-out, and dehydration in 50 mL polypropylene centrifuge tubes using procedures adapted from the QuEChERS method. The method was designed to reduce solvent consumption during purification with a multi-functional SPE column. For soybeans, citrate salts were used for pH adjustment and anhydrous magnesium sulfate was used for dehydration. For brown rice, a citrate buffer containing sodium chloride and additional sodium chloride were used for pH adjustment and salting-out, followed by partial removal of the lower aqueous phase. Purification was performed using InertSep VRA-PR (1,600 mg/6 mL),which contains a mixture of C18, PSA, and SAX, to obtain the final test solutions. A validation study was conducted over two days with five replicates at two fortification levels (0.01 μg/g and 0.1 μg/g).As a result, 268 pesticide compounds in brown rice and 231 in soybeans met the target criteria specified in the validation guidelines of the MHLW of Japan.