Gas chromatographic determination of thiabendazole in fruits as its methyl derivative

Quantitative determination of thiabendazole, as its methyl derivative, has been achieved by gas-liquid chromatography with flame ionization detection and a column of 10% of DC-200 on Gas-Chrom Q at 240 degrees. Determination was possible with 10 to 200 ng per mul of the methylated reaction mixture. For determining thiabendazole in fruits, clean-up of the crude extracts by liquid-liquid partition allows satisfactory elimination of interference and permits determination in concentrations down to 0.1 ppm. The recovery of thiabendazole added to fruits at the 0.5-ppm level ranges from 90.3 to 94.9%. The methyl derivative was identified as N-methylthiabendazole by its elementary composition, by its melting-point, and by ultraviolet, infrared, mass and nuclear magnetic resonance spectroscopy.