Development and optimization of a supercritical fluid extraction method for the analysis of aflatoxin B1 in grain dust.

A new method for the extraction of aflatoxins from small quantities of airborne dust, using supercritical carbon dioxide, is described. The efficacy of this method is compared with a previously used liquid extraction procedure, using naturally contaminated grain dust samples. Supercritical fluid extraction (SFE) provides faster, more sensitive, and more selective extraction, compared with the liquid extraction method. The optimized SFE conditions for 0.1-1.2 g of dust in a 2.5 mL extraction chamber are: 2000 psi, 40 degrees C, 15 mL of liquid CO2, static extraction for 15 min, and 250 microL of acetonitrile added to sample in the extraction chamber. A detection limit of 1 ng aflatoxin B1 per sample is obtained using off-line HPLC analysis with UV detection. Lower detection limits are obtained using on-line SFE and HPLC analysis with fluorescence detection.