Quantitative colorimetric determination of urinary p-aminophenol with an automated analyzer

• Published in: Clinical chemistry (Baltimore, Md.) Md.), 1997-04, Vol.43 (4), p.627-634
• Main Authors: Van Bocxlaer, Jan F, Clauwaert, Karine M, Lambert, Willy E, De Leenheer, Andre P
• Format: Article
• Language: English
• Subjects: Adult; Aminophenols - urine; Aniline Compounds; Autoanalysis; Biological and medical sciences; Chemical and industrial products toxicology. Toxic occupational diseases; Chlorides; Colorimetry - methods; Humans; Indicators and Reagents; Indophenol; Manganese Compounds; Medical sciences; Occupational Exposure; Reproducibility of Results; Resorcinols; Sensitivity and Specificity; Toxicology; Various organic compounds
• ISSN: 0009-9147; 1530-8561
• DOI: 10.1093/clinchem/43.4.627

We developed an automated colorimetric method for the quantitative determination of p-aminophenol with a Cobas Mira analyzer. The procedure can be used for the biological monitoring of human exposure to aniline. An absorbed aniline dose is extensively oxidized to p-aminophenol, which is excreted in urine mainly as glucurono- and sulfo- conjugates. After enzymatic hydrolysis, we reacted the free compound with resorcinol in the presence of manganese ions to form an indophenol dye, which is measured at 550 nm. Excellent accuracy (102.8%, 103.9%, and 96.8% at 2.5, 50, and 90 mg/L, respectively) and precision (7.7%, 2.1%, and 0.8% CV for within-run and 11.1%, 4.7%, and 4.6% for total reproducibility at 2.5, 50, and 90 mg/L, respectively) were achieved over a linear concentration range of 2.0 to 100 mg/L. The detection limit was 0.9 mg/L and no significant interference (except for o-aminophenol) was found for several investigated drugs and related compounds. The proposed method was used for a stability study and to analyze several samples from an occupational health screen.