Fast liquid chromatographic determination of urinary trans,trans-muconic acid

trans,trans-Muconic acid (1,3-butadiene-1,4-dicarboxylic acid, MA), a minor urinary metabolite of benzene exposure, was determined, after clean-up by solid-phase anion-exchange chromatography, by reversed-phase HPLC on a C-18 column (5 x 0.46 cm I.D., 3 mu m particle size), using formic acid-tetrahydrofuran-water (14:17:969) as mobile phase and UV detection at 263 nm. The recovery of MA from spiked urine was >95% in the 50-500 mu g/l range; the quantification limit was 6 mu g/l; day-to-day precision, at 300 mu g/l, was C.V.=9.2%; the run time was less than 10 min. Urinary MA excretion was measured in two spot urine samples of 131 benzene environmentally exposed subjects: midday values obtained in non-smokers (mean+/-S.D.=77+/-54 mu g/l, n=82) were statistically different from those of smokers (169+/-85 mu g/l, n=30) (P<0.0001); each group showed a statistically significant increase between MA excretion in midday over morning samples. Moreover, in subjects grouped according to tobacco-smoke exposure level, median values of MA were positively associated with and increased with daily smoking habits.