Development and validation of the LC-MS/MS method based on self-made purification column for simultaneous determination of novel organophosphate esters in rice-based products

Organophosphate esters (OPEs), as commonly used flame retardant and plasticizer, emerging organic pollutants, exhibit concerning contamination levels, particularly in widely consumed rice-based foods. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for simultaneous determination of 5 OPEs in rice-based products. According to recoveries and matrix effects as indicators, quality and proportion of different purification fillers were mainly optimized to fabricate a purification cartridge, simplifying and reducing the pre-treatment process and cost. The proposed method showed excellent linearity (0.08-500 μg kg^-1, with all correlation coefficients exceeding 0.99), with improved method detection and quantification limit (MDL and MQL): 0.0047-0.1309 and 0.0490-0.6479 μg kg^-1. Recoveries were 62.16-104.83 % with relative standard deviations (RSDs) at 0.67-15.83 % and negligible matrix effects (<20 %). Contaminants were widely detected (8.62-100 %) in real samples, with higher levels in rice bran than in rice, especially triethyl phosphate (TEP) (10.736 μg kg^-1) in southern China samples.