Analysis of Citrinin in Cereals, Red Yeast Rice Dietary Supplement, and Animal Feed by Immunoaffinity Column Cleanup and LC with Fluorescence Detection

Abstract

Abstract The analysis of citrinin in various cereals (wheat, oats, maize, rice, and rye and multigrain breakfast cereal), red yeast rice (dietary supplement and traditional medicine), distillers dried grain with solubles, and barley (animal feed) was carried out using a citrinin immunoaffinity column (IAC) for sample cleanup before LC analysis with fluorescence detection (LC-fluorescence). To establish method performance characteristics, wheat was spiked with citrinin at levels of 10–200 μg/kg, whereas red yeast rice was spiked at levels of 100–3000 μg/kg. Methanol–water (75 + 25, v/v) was used for the extraction of cereals and animal feed, and extraction was with 100% methanol for red yeast rice. Cleanup used a commercial citrinin IAC, followed by LC-fluorescence (λex, 330 nm; λem, 500 nm). Recoveries ranged from 80 to 110%, with r from 0.7 to 4.3%. The LOQ for citrinin in both wheat and red yeast rice was 10 μg/kg, with an LOD of 3 μg/kg. Satisfactory performance was demonstrated in a proficiency testing exercise for a sample of maize contaminated with both citrinin and ochratoxin A. It was concluded that the commercial citrinin IAC was capable of providing an efficient and effective cleanup of complex food and feed matrixes to enable citrinin to be reliably determined with the specific LC-fluorescence system used.