Determination of total pentachlorophenol in the urine of workers. A method incorporating hydrolysis, an internal standard and measurement by liquid chromatography.

Free pentachlorophenol (PCP) represents a small and variable fraction of total PCP excreted in the urine of exposed workers. A method incorporating hydrolysis is essential to be able to relate PCP excretion to absorbed dose. 3,5-Dichloro-2,4,6-tribromophenol (DTP) is added as an internal standard to a urine sample which is then acidified and steam-distilled. The distillate is made alkaline and extracted with methylene chloride to remove interferences. The distillate is then acidified and the phenols extracted into methylene chloride. The extract is evaporated, redissolved in acetonitrile and the PCP is measured using high pressure liquid chromatography (HPLC) using a 15 X 0.46 cm Spherisob-ODS 5 microns column with isocratic elution (H2O:CH3CN:CH3CO2H, 45:55:0.3 v/v). Detection is by fixed wavelength detector at 313 nm and calculation by the method of internal standardization. The biological threshold value used to trigger action to reduce exposure is 7 mg/l (corrected to a specific gravity of 1.024).