Green Chemistry in Urinalysis for Trichloroethanol and Trichloroacetic Acid as Markers of Exposure to Chlorinated Hydrocarbon Solvents

Abstract

The aim of the present study was to develop a method of urinalysis for trichloroacetic acid (TCA) and trichloroethanol (TCE), and therefore total trichloro-compounds (TTC) as the sum, with least use of hazardous chemicals, being green in that sense. After acid hydrolysis followed by dilution with an ethanol (EtOH)-methanol (MeOH)-water mixture, capillary gas-choromatography with an electron-capture detector can quantify TCA and TCE in the diluted hydrolyzate. Comparison studies showed that the results were identical among three methods, i.e., 1. the method developed in the present study, 2. a head-space GC with acid hydrolysis of conjugated TCE and methyl-esterification of TCA, and 3. traditional colorimetry with Fujiwara reaction. When applied to exposure-excretion analysis, the three methods gave results reproducible to each other. Over-all evaluation therefore was such that the method developed in the present study is as equally reliable as previously developed methods. It should be further noted that the procedures are very simple, with minimum use of occupationally or environmentally hazardous chemicals. In case the determination of only TCA is requested, it is possible to skip the hydrolysis step so that the treatment prior to the GC analysis is even simpler, i.e., just a 60-fold dilution of the urine sample with the EtOH-MeOH-water mixture. It was also demonstrated that correction of urinary analyte levels for urine density in terms of creatinine or specific gravity did not improve the correlation with the intensity of TRI exposure.