Application and validation of a clean-up tandem assay column for screening ochratoxin A in cocoa powder

Abstract

A rapid antibody-based assay for the detection of ochratoxin A in cocoa powder is described, involving sequential clean-up and visual detection of the toxin (“clean-up tandem assay column”). The screening test was developed to have a cut-off level of 2 µg kg⁻¹ and was shown to have false positive and false negative rates of 10 and 2%, respectively. Analysis of six samples can be carried out in the field in approximately 30 min by untrained workers. Using the proposed rapid screening test, 10 retail cocoa powders were found to contain no detectable levels of ochratoxin A (<2 µg kg⁻¹). These samples were also found to be negative (<2 µg kg⁻¹) when analysed using an LC–MS/MS method.

Keywords:

• Ochratoxin A
• cocoa powder
• immunoassay
• qualitative test
• validation

Acknowledgement

This work was financially supported by Bijzonder Onderzoeksfonds (BOF) of the Ghent University (011D02803) and FWO Flanders Research Project No. G.0312.03.