Determination of zearalenone in grains by high-performance liquid chromatography-tandem mass spectrometry after solid-phase extraction with RP-18 columns or immunoaffinity columns

In this paper a robust, sensitive and selective LC-MS-MS method for the det ermination of zearalenone (ZON) in several cereals is described. Sample pre paration was performed by extraction of the commodities with a mixture of a cetonitrile and water followed by solid-phase extraction with RP-18 columns or immunoaffinity columns. The selective determination of ZON was achieved with an atmospheric pressure chemical ionization interface. Using the nega tive ion mode a detection limit of 0.5 mu g/kg and a determination limit of 1 mu g/kg grain was achieved, which is by a factor of 100 more sensitive t han the positive ion mode. Zearalanone (ZAN), which does not occur in natur e, was used as internal standard for quantification. A linear working range from 1.0 mu g/kg to 1000 mu g/kg could be achieved in grains with a standa rd deviation of 4% and recovery rates around 100%. All these results were i ndependent from the grain matrices (maize, barley, oats, wheat) when ZAN wa s used as internal standard. Sample preparation with RP-18 and immunoaffini ty materials gave comparable results. In addition, the method was successfu lly used for the investigation of naturally contaminated maize samples in t he course of an interlaboratory comparison test. (C) 1999 Elsevier Science B.V. All rights reserved.