1992 Volume 34 Issue 2 Pages 126-130
The aim of this study was to elucidate the time courses of amounts of urinary p-chloroaniline (p-CA) metabolites during acute poisoning and to establish a suitable method for biological monitoring of exposure to p-CA. Urinary p-CA metabolites which were previously identified in a patient with acute p-CA poisoning were determined quantitatively over time during admission of a patient by high-performance liquid chromatography (HPLC) and by the colorimetric method of diazo-positive metabolites (DPM). The data of urinary excretion of each p-CA metabolite were fitted to two-compartment model of pharmacokinetics.
Major urinary metabolites of p-CA were conjugated p-CA and conjugated 2-amino-5-chlorophenol (2-A-5-CP), and the detected amounts of 2, 4-dichloroaniline (2, 4-DCA) and free p-CA were small. During the rapid phase for the disappearance of each metabolite, half lives of p-CA, 2-A-5-CP and 2, 4-DCA were 2.4, 1.7 and 1.7 h, respectively, and during the slow phase, they were 4.5, 3.3 and 3.8 h, respectively. Urinary p-CA occupied about 62% of the total metabolites detected in the urine, 2-A-5-CP about 36%, and 2, 4-DCA about 1%. 2-A-5-CP and p-CA were detected in the urine of the patient obtained on days 3 and 4, respectively, after the poisoning, but the amount of DPM after the second day of the poisoning was in the ranged of that of non-exposed persons.
As the colorimetric method was not accurate for biological monitoring at a low level exposure of p-CA, measurement of urinary p-CA or 2-A-5-CP by HPLC is considered to be more suitable for biological monitoring of p-CA exposure.
