Three liquid chromatographic methods for the analysis of aflatoxins in for different corn (Zea mays) matrices

Liquid chromatographic analyses of aflatoxins (AFs) in corn, with post-column derivatization using a photochemical reactor for enhanced detection (PHRED) and a Kobra electrochemical cell system were compared with the pre-column derivatization method using trifluoroacetic acid (TFA). AFs in four different corn matrices were analyzed and validated in terms of the limit of detection (LOD), limit of quantification (LOQ), linearity, accuracy, and precision. The LOD and LOQ for the PHRED, Kobra, and TFA methods were 0.004–0.03, 0.01–0.05, and 0.03–0.17 ng/g, respectively, and 0.01–0.10, 0.02–0.14, and 0.11–0.51 ng/g, respectively. Accuracy expressed as average recoveries was 79–110% for PHRED, 70–109% for Kobra, and 77–133% for TFA. In the three derivatization methods, the mean recoveries of AFs were significantly different, at some but not all concentrations, between matrices of dehulled corn and corn with hull (p < 0.05). For dehulled yellow corn, the TFA method consistently gave slightly poor recovery values for AFs B1 and G1 than did the PHRED and Kobra methods. The values for the TFA methods were improved by using a modified cleanup procedure. These results indicate that PHRED and Kobra derivatization methods as well as TFA method comply with the analytical requirements for AF analyses in corns.