BIOLOGICAL MONITORING OF EXPOSURE TO N-HEPTANE BY GAS-CHROMATOGRAPHICMASS-SPECTROMETRIC DETERMINATION OF ITS METABOLITES

Urine samples from 10 workers that had been exposed to n-heptane were analysed by the GC/MS technique to verify the concentrations and the r elative abundances of its metabolites. The procedure of sample prepara tion has undergone some modifications with respect to the Perbellini m ethod and the mass spectrometric detection was carried out in selected ions monitoring conditions. The analyses of samples collected during three different workshifts showed that 2-heptanol was not the main met abolite and that the remains of 2-heptanone, valerolactone and 2,5-hep tanedione were present at the beginning of the successive work-week at 12, 34 and 39% of the average values found at the end of the previous week. Overall, a very slow excretion rate was detected for the last m etabolite. The main and significant metabolite at the end of the two w orkshifts was 2-heptanone which was detected in urine at average value s of 413 and 238 mu g g(-1) creatinine. This urinary ketone correlated better than other metabolites with respect to the airborne n-heptane at the end of both the workshift and work-week. These preliminary data suggest that further studies should be carried out to confirm whether 2-heptanone is really useful as an n-heptane marker in biological mon itoring.