Analysis of Acephate, Methamidophos and Omethoate in Animal and Fishery Products, and Honey by LC-MS

Abstract

We studied the simultaneous determination of acephate, methamidophos, and omethoate in animal and fishery products, their processed foods, and honey by means of liquid chromatography coupled with mass spectrometry (LC-MS). The sample was extracted with ethyl acetate in the presence of anhydrous Na₂SO₄ (and diatomaceous earth for honey). An aliquot of the crude sample extract was loaded into the GPC system, and the pesticide fraction was selectively collected. The extract was cleaned up on a PSA mini-column, and determined by a column-switching ESI-SIM mode LC-MS. Mean recoveries (2 replicates×5 days) of compounds from eleven kinds of samples, except honey, fortified at the analyte concentration of 0.05 μg/g were from 71.4% to 98.4%. The repeatability relative standard deviation values were ≤12.5%, and the intermediate reproducibility relative standard deviation values were ≤14.1%. In honey, the recoveries were improved to 97.6-98.6% by using highly purified surrogates.