In the past ten years or so, Hetol, 1, 4-bis(trichloromethyl)benzene or hegachloro-p-xylene (HCX), has been widely used in many fields and particular in therapy as a parasiticide. In order to monitor its accumulation in the body a rapid, sensitive and convenient method for quantitative micro determination of this compound needs to be established. D. Katz reported in 1964 that an acetone solution of diphenyla,mine and zinc chloride develops color with chlorocompounds in thin layer chromatography.