Abstract Objective: To establish a convenient method
by high-pressure liquid chromatography (HPLC) to
measure toluene in urine as a marker of occupational
exposure to toluene. Methods: As soon after sampling as
possible, 1 ml of urine was mixed with an equal volume
of acetonitrile in a 2.2-ml HPLC glass bottle, and the
bottle was tightly sealed and stored at 4 °C. Immediately
before HPLC determination, 100 ll methanol was added
to the mixture to prevent confounding eects of
glycosuria, and the bottle was spun to remove any suspended
matter. An aliquot of the supernate was introduced
into the HPLC system and analyzed on a
PRODIGY column, with an acetonitrile ± perchloric
acid ± phosphoric acid ± water mixture serving as the
mobile phase. The euent was monitored at 191 nm.
Results: The method can measure toluene in urine every
20 min; the detection limit was 2 lg/l, the coecient of
variation was less than 5%, and the recovery rate was
100%. No signi®cant reduction in toluene concentration
was observed for 1 week after storage at 4 °C. When the
method was applied to end-of-shift urine samples from
13 male workers exposed to toluene at 18±140 ppm and
also to urine samples from 10 nonexposed male controls,
toluene in urine was linearly related to toluene exposure
concentration, with a regression line passing close to the
origin. The correlation coecient was as high as 0.97
(n 23). No toluene was detected in control urine