A Biological Monitoring Method for o-Toluidine and Aniline in Urine Using High Performance Liquid Chromatography with Electrochemical Detection

Abstract

A urinalysis method for o-toluidine and aniline was developed for biological monitoring. Urine specimens were made 4.7 M in sodium hydroxide and heated at 80°C for 2 hours to convert the metabolites acetanilide and N-acetyl-o-toluidine to the free amines. Extraction of the hydrolysate with butyl chloride and back extraction with 0.1 M aqueous hydrochloric acid gave an amine fraction, which was subjected to paired-ion reversed-phase liquid chromatography with coulometric electrochemical detection. For o-toluidine and aniline, respectively, the average recovery was 91 and 100 percent, the precision for field specimens was 13 and 16 percent relative standard deviation, and the limit of detection was 0.6 and 1.4 μg/L. This method was applied to 171 urine specimens from chemical plant workers. The median levels for o-toluidine were: exposed preshift, 11 μg/L; exposed postshift, 65 μg/L; nonexposed preshift, 0.7 μg/L; non-exposed postshift, 2.6 μg/L. For aniline the median levels were: exposed preshift, 11 μg/L; exposed postshift, 23 μg/L; nonexposed preshift, 2.0 μg/L; nonexposed postshift, 3.2 μg/L. The urinary levels of the two amines, especially o-toluidine, demonstrated significant uptake of the amines during the work shift and an accumulation of part of the dose with each passing work shift.