Determination of zearalenone and its metabolites alpha- and beta-zearalenol in beer samples by high-performance liquid chromatography-tandem mass spectrometry

A fast, robust and sensitive LC-MS-MS method for the determination of zeara lenone (ZON) and its metabolites alpha-zearalenol (alpha-ZOL) and beta-zear alenol (beta-ZOL) in beer samples is described. Sample preparation was perf ormed by direct RP-18 solid-phase extraction of undiluted beer samples foll owed by selective determination of analytes by LC-MS-MS applying an atmosph eric pressure chemical ionization (APCI) interface. Using the negative ion mode Limits of determination of 0.03-0.06 mu g l(-1) beer and limits of qua ntification of 0.07-0.15 mu g l(-1) beer were achieved, which was distinctl y more sensitive than in the positive ion mode. Twenty-three beer samples f rom different countries, produced from different grains and under different brewing conditions, were investigated by this method, but only in one samp le could beta-ZOL and ZON be detected. Independently of the type of beer, r elative standard deviations between 2.1% and 3.3%, a linear working range o f 0.15 mu g l(-1) to 500 mu g l(-1) beer and recovery rates around 100% cou ld be achieved when zearalanone (ZAN) was used as internal standard. (C) 20 00 Elsevier Science B.V. All rights reserved.