Abstract
<jats:p>A method for quantitation of 4-Methylumbelliferone (4-MU), the aglycone of 4-Methylumbelliferone b-D-Glucuronide (4-MUG), in urine was validated. 4-MUG was spiked into urine samples, incubated at physiological temperature for four hours, and 4-MU concentration determined utilizing reversed phase Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS). Linearity was demonstrated over the concentration range from 10ng/mL to 1,000ng/mL. Matrix effects were not significant for the lots of urine used in the present validation. Percent accuracy ranged from 93.01% to 102.87%, and the coefficient of variation ranged from 0.89% to 7.26% for 4-MU over the concentration range. The results of the validation process described below illustrate the suitability of this method in the pursuit of urinary β-Glucuronidase (GUSB) activity quantification. This method represents a vast improvement upon currently available colorimetric or fluorometric assays for β-Glucuronidase activity, both of which perform poorly in urine samples.</jats:p>