Abstract
A simultaneous official method was developed for the determination of phorate and its metabolites (phorate sulfoxide, phorate sulfone, phorate oxon, phorate oxon sulfoxide, phorate oxon sulfone) in livestock samples. The analytes were quantified and confirmed via liquid chromatograph-tandem mass spectrometer (LC-MS/MS) in positive ion mode using multiple reaction monitoring (MRM). Phorate and its metabolites were extracted from beef and milk samples with acidified acetonitrile (containing 1% acetic acid) and partitioned with anhydrous magnesium sulfate. Then, the extract was purified through primary secondary amine (PSA) and C18 dispersive sorbent. Matrix matched calibration curves were linear over the calibration ranges (0.005-0.5 mg/L) for all the analytes into blank extract with $r^2$ > 0.996. For validation purposes, recovery studies were carried out at three different concentration levels (beef 0.004, 0.04 and 0.2 mg/kg; milk 0.008, 0.04 and 0.2 mg/kg, n = 5). The recoveries were within 79.2-113.9% with relative standard deviations (RSDs) less than 19.2% for all analytes. All values were consistent with the criteria ranges requested in the Codex guidelines. The limit of quantification was quite lower than the maximum residue limit (MRL) set by the Ministry of Food and Drug Safety (0.05 mg/kg). The proposed analytical method was accurate, effective and sensitive for phorate and its metabolites determination and it will be used to as an official analytical method in Korea.
이 연구는 축산물 중 포레이트 및 대사산물 5종의 안전관리를 위한 공정분석법을 확립하기 위하여 수행하였으며 분석법의 선택성, 검출한계 및 정량한계, 회수율에 대한 검증을 통하여 포레이트 및 대사산물 5종의 공정시험법으로의 유효성을 확인하였다. 포레이트 및 대사산물 5종을 신속하고 효과적으로 동시에 분석하기 위하여 LC-MS/MS를 사용하였고, 1% 아세트산 포함 아세토니트릴 추출 후 PSA, C18을 이용해 정제하였다. 개발된 분석법의 평균 회수율은 79.2-113.9%였으며, 분석오차는 19.2% 이하로 정확성 및 재현성이 우수함을 확인할 수 있었다. 개발된 분석법은 국제적 잔류농약 분석 가이드라인에 적합한 수준이었으며 축산물 중 포레이트 및 대사산물 5종의 잔류검사를 위한 공정분석법으로 활용할 수 있을 것으로 판단된다.
