Development of a Gas Chromatographic Test for the Quantitation of the Biomarker 2-Butoxyacetic Acid in Urine Samples

An accurate and precise method is developed and evaluated for the detection and quantitation of 2-butoxyacetic acid (2-BAA), a metabolite and biomarker for human exposure to 2-butoxyethanol. The solvent 2-butoxyethanol (2-BE) is extensively used in various industrial and domestic applications, and it is a health concern owing to its toxicity. Sample preparation consists of liquid-liquid extraction (LLE) of urine, then esterification of 2-BAA to produce the ethyl ester analog. The gas chromatographic conditions utilize a dimethyl polysiloxane phase (HP-1) capillary column and a mass spectrometer (MS) for detection of the analyte. Validation of this method includes a recovery study using fortified urine samples, which demonstrated good accuracy and precision; recovery varied between 100% and 102% of theory, with relative standard deviations of replicate samples at 2.8% and less. The detection limit of this method ranges from 0.005 to 0.015 µg/mL equivalent level of 2-BAA in urine.