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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, IC(50) 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 B(1) (AFB(1)), 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., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Citrinin (CIT)-protein synthetic antigen was prepared by conjugating CIT with keyhole limpet hemocyanin by 1,4-butanediol diglycidyl ether. The ultraviolet and infrared spectrometry analyses indicated that CIT was conjugated with the carrier protein successfully. By fusion and cloning, a hybridoma cell line K2-F3 which stably secreted the highly specific monoclonal antibody (McAb) against CIT was obtained. The indirect competitive ELISA showed that the IC50 value was 0.3 ng/mL and the limit of detection, 0.01 ng/mL. Cross-reactivity was less than 0.01% with four mycotoxins, aflatoxin B1, ochratoxin A, zearalenone, deoxynilvalenol and three pigments, rubropunctatine, rubropunctamine, monascin. The mean recovery of citrinin from artificially contaminated red yeast rice was from 89 to 92%, with CVs from 6.8 to 9.0%. The ELISA developed in this study can accurately determine CIT in artificially contaminated red yeast rice. [ABSTRACT FROM PUBLISHER]

Abstract: Monascus products have been widely used as food additives and pharmaceuticals. Citrinin is a toxic metabolite produced during the Monascus fermentation. In this work, a quick extraction method with ultrasonic treatment was studied for a complete extraction of citrinin from the fungi cells. Furthermore, the proposed HPLC method has the advantage of the simultaneous determination of Monascus pigments and citrinin without sample pretreatment. Under the optimized HPLC conditions, a baseline resolution of pigments, citrinin and other catabolites was achieved. The detection limit of citrinin reached 0.5ngmL−1 (S/N >3/1) with a fluorescence detector (FD). Eight Monascus pigments were detected, with photodiode array detector (PAD), two of which not yet described. The HPLC fingerprint profile of the eight Monascus pigments and citrinin appears significant for the quality control of the Monascus product. [Copyright &y& Elsevier]