DETERMINATION OF FUMONISIN B-1 CORN BY INSTRUMENTAL THIN-LAYER CHROMATOGRAPHY

An instrumental TLC method has been developed for quantification of fu monisin B-1 (FB1), a mycotoxin from Fusarium moniliforme (Sheldon), in corn. Samples of ground corn free from FB1 were spiked at different l evels (5 to 350 mg/kg) with crude FB1 extracts. After extraction and p urification by solid phase extraction, FB1 was separated by 2-step TLC and quantified by scanning densitometry after postchromatographic der ivatization. The suitability of various solvent systems for dissolutio n of FB1 was studied, as was their influence on spotting. Two reagents , p-anisaldehyde and ninhydrin were compared in terms of sensitivity, specificity, and stability of detection, the higher response and lower limit of detection being obtained with p-anisaldehyde. A delay of 30 min. between derivatization and quantification minimized the error res ulting from response decay. The repeatability of the calibration curve fluctuated from 2 to 10 % (RSD) and the limit of detection was 51.1 n g for standards and 100 ng for extracts. The limit of quantification w as 100 mg/kg (ppm) without purification and 5 ppm after purification. Recoveries were greater than 80 % for levels in excess of 25 ppm and 6 7.6 % at the limit of quantification (5 ppm). The main source of error was the error of spotting: +/-4.02 % (RSD). Intraplate and interplate variation were +/-4.98 % and +/-6.50 % (RSD), respectively. The techn ique appeared adequate for detection of FB1 in foodstuffs at the maxim um recommended level (5 ppm).