Aflatoxin in raw walnut kernels marketed in Tehran, Iran.

The occurrence of aflatoxin in 35 samples of raw walnuts, which were randomly collected from Iranian supermarkets in Tehran, was examined. Analysis of aflatoxin was performed by solvent extraction and immunoaffinity clean-up followed by determination using high-performance liquid chromatography with fluorescence detection. Limits of detection (LOD) for the aflatoxins were 0.03-0.25 ng g⁻¹. Limits of quantification (LOQ) were 0.12-0.80 ng g⁻¹. Total aflatoxin concentrations in the samples ranged from 0 to 112.8 ng g⁻¹. About 74.3% of the samples were contaminated with aflatoxins, of which 20.0% exceeded the maximum tolerable limit of 15 ng g⁻¹ set by Codex.