Microsphere-based flow cytometric immunoassay for the determination of citrinin in red yeast rice

The determination of citrinin (CIT) by a microsphere-based flow cytometric immunoassay (MFCI) has been developed. In the method, the carboxyl-modified microspheres were conjugated with CIT-Ovalbumin (OVA) antigen. CIT competed with the CIT-OVA antigen on the surface of the microspheres for the anti-CIT McAb. Under the optimised conditions, IC50 value was 1.0 ng/mL and the limit of detection reached 0.005 ng/mL. The cross-reactivity was less than 0.01% against each of the four mycotoxins such as aflatoxin B1 (AFB1), ochratoxin A (OTA), zearalenone (ZEA), deoxynilvalenol (DON). In the work, the MFCI could accurately determine CIT in the real red yeast rice. The systematic error was low with the coefficient of variation (CV) from 5.24% to 8.16% by the MFCI. The mean recovery of CIT from artificially contaminated red yeast rice was from 89% to 94%, with CV from 7.2% to 8.7%. The experimental data showed that the precision, sensitivity and specificity of the developed MFCI method for the determination of CIT were satisfactory.