Development of a sensitive competitive indirect ELISA method for determination of ochratoxin A levels in cereals originating from Nanjing, China

A monoclonal antibody against ochratoxin A (OTA) was produced and a simple, rapid and reliable competitive indirect ELISA (ci-ELISA) for detection of OTA was developed. The 50% inhibitory concentration (IC50) was 1.70 ng/mL, with a detectable range of 0.55–6.75 ng/mL, and a limit of determination (LOD) at 0.15 ng/mL. The cross-reactivity of the antibody against ochratoxin B was 17%, and <10% against deoxynivalenol, fumonisin B1 or aflatoxin B1. A survey of 65 cereal samples was carried out in Nanjing, the capital of Jiangsu Province, China. The frequencies of OTA contamination were 36.36%, 26.08% and 15.00%, and the mean concentrations of positive samples were 4.248 ng/g, 7.360 ng/g and 3.382 ng/g for wheat, corn and rice, respectively. The results of this study suggest that the ci-ELISA developed can be used to determine OTA in agricultural commodities such as cereals, and a survey might be needed to investigate OTA contamination in food and feed to prevent their harmful health effects.