Comparison of solvents and methods of extracting methylbenzimidazol-2-yicarbamate (MBC) from tobacco

The bioautographic method of Homans and Fuchs for detecting MBC on thin layer plates, was tested quantitatively. The sum of the vertical and horizontal diameters of the zones of inhibition of Penicillium expansum, and the square root of the mass of an equal area of paper, were directly proportional to the logarithm of the concentration of MBC. Methanol and ethanol extracted significantly more MBC from tobacco tissue than acetone and chloroform. Soxhlet extraction was more effective than cold (22 °C) treatment, but the latter, in which 100 mg aliquots of dried tissue were used, was the least variable, very much quicker and could be used to detect the fungicide in small amounts of individual plant tissues.