Biological monitoring of exposure to n-heptane by gas chromatographic mass spectrometric determination of its metabolites

Abstract 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 relative abundances of its metabolites. The procedure of sample preparation has undergone some modifications with respect to the Perbellini method 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 metabolite and that the remains of 2-heptanone, valerolactone and 2,5-heptanedione 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 metabolite. The main and significant metabolite at the end of the two workshifts was 2-heptanone which was detected in urine at average values of 413 and 238 μg 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 monitoring.