Determination and Residue Survey of Novel Nicotinic AcetylcholineReceptor Modulator Pesticides in Brown Rice by LC-MS/MS

Nicotinic acetylcholine receptors (nAChRs) are neurotransmitter receptors found in the nervous system of many organisms, including humans. Neonicotinoid pesticides act as nAChRs modulators that affect neurotransmission. Due to toxicity effects, their use has been restricted. However, a new class of modulators (nAChRMs) have been developed, but analytical methods for the detection of residues of these new pesticides in agricultural crops have not been established. Therefore, this study aimed to develop and validate an accurate determination method for novel nAChRMs, such as sulfoxaflor, flupyradifurone, flupyrimin, and triflumezopyrim in brown rice using liquid chromatography with tandem mass spectrometry (LC-MS/MS). The method was applied to commercially available brown rice samples from Tokyo, Japan. Target analytes were extracted with acetonitrile, cleaned with GC/PSA, and then cleaned again with MonoSpin PBA. In accordance with the method validation guidelines for residual pesticides in foods, the performance characteristics were evaluated, with trueness ranging from 86.3% to 98.2%, repeatability of less than 6.5% relative standard deviation (RSD), and within-laboratory reproducibility of less than 6.5% RSD. These results indicate that the developed method can be applied to residue surveillance of target analytes using solvent standard calibration curves. By applying the developed method to 53 brown rice samples commercially available in Tokyo, sulfoxaflor residues were found in two samples at concentrations of 3.7 and 21.9 ng/g. This is the first report of the detection of sulfoxaflor residues in domestic agricultural products.