Comparison of two different derivatization procedures for the determination of urinary chlorophenol excretions

A GC/MS method with enhanced sensitivity and specificity suitable for the determination of various chlorophenols in the urine of persons occupationally and environmentally exposed to diverse chlorinated aromatic hydrocarbons has been elaborated and compared with the method customarily used. After acid hydrolysis and steam distillation, followed by several clean-up steps, the chlorophenols have been derivatized with N-heptafluorobutyrylimidazole (HFBI), yielding ester derivatives. This procedure facilitates the detection of 3-and 4-monochlorophenol, 2,4- and 2,5-dichlorophenol, 2,4,5-and 2,4,6-trichlorophenol as well as 2,3,4,6-tetrachlorophenol down to 0.1–1 μg/l, depending on the number of chlorine atoms. A comparison to the commonly used derivatization procedure with diazomethane revealed, except for 2,4,5-trichlorophenol, satisfactory conformity of both techniques. Due to an improvement of the detection limit by a factor of five for the monochlorophenols, for the first time the quantification of 3-monochlorophenol and the identification of 2-monochlorophenol as constituents of human urine have been possible as HFBI-derivatives. The excretion of mono-, di-, tri- and tetrachlorophenols in the urine of the general population could be confirmed.