A method of analysis for determination of aflatoxins in chocolate

Abstract

A method of analysis for determination of aflatoxins (AFs) in chocolate was optimized and evaluated its within laboratory precision. The method uses acetonitrile-methanol-water (60+10+40, v/v/v) as extraction solvent and an immunoaffinity column (IAC) for the cleanup, and HPLC with fluorescence detection for the determination of AFs. The method was validated by testing replicate analyses of the finally ground chocolate samples spiked at 0.1 and 10.0 μg/kg for each AFB₁, AFB₂, AFG₁ and AFG₂. The average recovery of AFs at 0.1 and 10.0 μg/kg spiking levels ranged from 90 to 97 % for all AFs. The relative standard deviation (RSD) for within day and between day ranged from 1.7 to 3.3 %, and 0 to 4.1 % for all AFs, respectively. The HorRat for the total RSD at each level was within 0.2 for all AFs. These results show that this method is reliable for the analysis of AFs in chocolate in the range of 0.1 and 10.0 μg/kg.