Single laboratory validation for a method of analysis for ochratoxin A in rice and buckwheat

Abstract

Ochratoxin A (OA) is a mycotoxin produced by certain Aspergillus and Penicillium fungi. Contamination with OA can occur in many foods such as cereals, coffee, wine, dried fruits, and meat products. However, little is known about ochratoxin contamination on rice, which is a staple food for many Asian countries. In this study we examined a method of analysis for OA in rice and buckwheat. Five types of samples, polished japonica type rice (short grain), polished glutinous rice, rough japonica type rice, rough indica type rice (long grain) and buckwheat (two samples) were tested. Samples were spiked with OA over the range from 0.1 to 10.0 μg/kg for the linearity study and at 0.5 and 5.0 μg/kg for the reproducibility study. Ochratoxin A was extracted with acetonitrile/water, isolated using an immunoaffinity column, separated by HPLC, and detected by fluorescence. At 0.5 μg/kg level, within day recoveries were 64.5 to 110.2 % and Relative Standard Deviations (RSDs) were 5.7 to 16.7 % and between days, recoveries were 55.8 to 99.6 % and RSDs were 4.3 to 15.0 %. Average recoveries of OA in the range of 0.2 to 10 μg/kg were 89.6 to 118.1 %. From these result, it is shown that this method can be applied for the analysis of OA present as a contaminant in rice and buckwheat in the range from 0.2 to 10 μg/kg.