Development and inter-laboratory study of a method for quantifying ochratoxin A in pet foods

Abstract

An analytical method for quantifying ochratoxin A (OTA) in pet foods using high-performance liquid chromatography was developed, and an inter-laboratory study was conducted. OTA was extracted from samples with aqueous acetonitrile. The extract was purified by an immunoaffinity column, OCHRAKING, and analysed by high performance liquid chromatography with fluorescence detection. The limits of quantification by this method were 2 µg/kg for dry and semidry pet food and 1 µg/kg for wet type pet food. The calibration curve showed linearity in the range of 0.5-50 ng/ml (equivalent to 1-100 µg/kg for wet type pet food). The mean recoveries of OTA spiked at 1-5 µg/kg were in the range of 83.0-106% and relative standard deviations of the in-house method validation were 2.6-6.8%. The mean recoveries, repeatability, reproducibility and the Horwitz ratios for OTA from the inter-laboratory validation study were 75.6-83.1%, 3.5-6.1%, 5.0-15.0% and 0.23-0.68, respectively.