Determination of the mycotoxin, sterigmatocystin, by thin-layer chromatography and reagent-free derivatisation

This paper describes a thin-layer chromatographic (TLC) method, which allows the determination of sterigmatocystin at a level of 2 mug/kg in various cereal grains of interest. Sterigmatocystin is extracted from the food matrix and further purified by phenyl-bond solid-phase extraction (SPE). The separation and identification is performed on an amino-derivatised high-performance TLC (HP-TLC) plate. The derivatisation for densitometric measurement and visual inspection is achieved reagent free by heating the plate. Sterigmatocystin results in highly fluorescent spots. The method has shown good recovery values for the various cereals analysed (e.g., around 80% for wheat). The method was applied for monitoring the sterigmatocystin content in 85 cereal samples, purchased from the local (Italian) market in 2002. However, none of the samples was found to be positive, indicating that this mycotoxin was not a problematic contaminant in products of this particular region and in this specific year.