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Analysis of processing contaminants in edible oils. Part 1. Liquid chromatography-tandem mass spectrometry method for the direct detection of 3-monochloropropanediol monoesters and glycidyl esters.
A new analytical method has been developed and validated for the detection of glycidyl esters (GEs) and 3-monochloropropanediol (3-MCPD) monoesters in edible oils. The target compounds represent two classes of potentially carcinogenic chemical contaminants formed during the processing of edible oils. Target analytes are separated from edible oil matrices using a two-step solid-phase extraction (SPE) procedure. The extracts are then analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with electrospray ionization (ESI). Chromatographic conditions that separate sn-1 and sn-2 monoesters of 3-MCPD have been developed for the first time. The method has been validated for GEs, sn-1 3-MCPD monoesters of lauric, myristic, linolenic, linoleic, oleic, and stearic acids, and sn-2 3-MCPD monoesters of oleic and palmitic acids in coconut, olive, and palm oils using an external calibration curve. The range of average recoveries and relative standard deviations (RSDs) across the three oil matrices at three spiking concentrations are 84-115% (3-16% RSD) for the GEs, 95-113% (1-10% RSD) for the sn-1 3-MCPD monoesters, and 76.8-103% (5.1-11.2% RSD) for the sn-2 3-MCPD monoesters, with limits of quantitation at or below 30 ng/g for the GEs, 60 ng/g for sn-1 3-MCPD monoesters, and 180 ng/g for sn-2 3-MCPD monoesters.
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