ANALYSIS OF METHYLHEXAHYDROPHTHALIC ACID IN HUMAN URINE

A method for analysis of urinary methylhexahydrophthalic acid (MHHP ac id), a metabolite of the highly sensitising methylhexahydrophthalic an hydride, is described. The method is based on a double liquid-solid ex traction of the MHHP acid from urine, esterification with methanol and boron trifluoride catalysis, and analysis with gas chromatography-mas s spectrometry in the electron impact mode. The detection limit was 3 ng mL(-1) and the precision between 2 and 5 % in the range 34 to 340 n g mL(-1). The method gave similar results compared to another method. Urine stored for five years at -20 degrees C lost between 38 and 86 % of the MHHP acid (range 16-85 ng mL(-1)).