Determination of Urinary 2-Ethoxyacetic Acid as an Indicator of Occupational Exposure to 2-Ethoxyethanol

Abstract

Abstract A biological monitoring method which can detect human exposure to glycol ethers is described. A procedure for measurement of 2-ethoxyacetic acid (EAA), a urinary metabolite of 2-ethoxyethanol (EE), has been validated. EAA is removed from the urine specimen by a methylene chloride extraction of an EAA-tetrabutyl ammonium hydrogen sulfate ion pair. The ion pair subsequently reacts with pentafluorobenzyl bromide to produce the pentafluorobenzyl derivative of EAA. The EAA derivative is separated from other co-extracted urinary constituents by packed column gas chromatography and quantitated with flame ionization detection. 2-Butoxyacetic acid and 2-methoxyacetic acid can also be separated by this procedure. The analytical range for EAA is 5 to 100 μg/ml of urine; the limit of detection is 4 μg/ml, while the limit of quantitation is 7 μg/ml. The day-to-day relative standard deviation (Sr) was better than 4.7 percent; the corresponding within-day Sr was less than 2.0 percent. The procedure has been applied to urine specimens collected from shipyard workers exposed to paints containing 2-ethoxyethanol. Preliminary results indicate this procedure can detect human occupational exposure to EE.