Determination of zearalenone in cereals by high-performance liquid chromatography and liquid chromatography-electrospray tandem mass spectrometry

Zearalenone is a mycotoxin produced mainly by fungi belonging to the genus Fusarium in foods and feeds. A rapid and accurate method to quantify zearalenone in cereals was described. The determination of zearalenone was performed using immunoaffinity column for clean-up, high-performance liquid chromatography (HPLC)/fluorescence for quantification and liquid chromatography/electrospray tandem mass spectrometry (LC/ESI-MS-MS) for confirmation. Cereal samples were extracted with acetonitrile-water (90:10, v/v) prior to a Vicam ZearalaTest™ immunoaffinity column clean-up. Zearalenone was eluted from the column with methanol and quantified by HPLC with fluorescence detection (λex = 274 nm, λem = 440 nm). A mobile phase of acetonitrile-water (50:50, v/v) and a flow rate of 1.0 mL/min-1 were used. Average recoveries of zearalenone from cereals spiked at levels of 5, 20, 100 and 200 ppb ranged from 66.4% to 96.1%. The limit of quantitation was 5 ppb. The selective determination of zearalenone was achieved by LC/MS-MS with an electrospray (ESI) ionization interface. Using the negative ion mode, the parent ion of m/z 317 and the product ion of m/z 175 were selected. The quantification limit of 3 ppb was achieved. Seven mixed cereals samples, seven corn samples, five wheat samples, five rice samples and two oat samples were analyzed. The results showed that zearalenone was detected in four corn samples ranging from 7.9 to 9.0 ppb. Using the consumption data from "Nutrition and Health Survey in Taiwan 1993-1996", the zearalenone consumption for Taiwanese adults (male and female are 0.00297 and 0.00478 μg/kg b.w. respectively) was much lower than the tolerable daily intake of 0.5 μg/kg b.w. established by JECFA.