BIOMARKERS OF TOLUENE DIISOCYANATE AND THERMAL-DEGRADATION PRODUCTS OF POLYURETHANE, WITH SPECIAL REFERENCE TO THE SAMPLE PREPARATION

The amines corresponding to 2,4- and 2,6-toluene diisocyanate (TDI) an d 4,4'-methylenediphenyl diisocyanate viz. 2,4- and 2,6-toluenediamine (TDA) and 4,4'-methylenedianiline (MDA), respectively, in urine and p lasma were determined under different hydrolysis conditions. The relea se and stability of 2,4-TDA, 2,6-TDA and 4,4'-MDA with time were studi ed in (A): plasma and urine from workers exposed to TDI and thermal de gradation products of MDI-based polyurethane (PUR); (B) for MDI and TD I urea and urethane derivatives and (C) for 2,4-TDA, 2,6-TDA, 4,4'-MDA and trideuterated 2,4- and 2,6-TDA and dideuterated 4,4'-MDA at 100 d egrees C, using HCl, H2SO4 and NaOH. In the biological samples an incr eased release of 2,4-TDA, 2,6-TDA and 4,4'-MDA with hydrolysis time wa s found using acidic conditions. Alkaline hydrolysis released twice mo re. The hydrolysis recoveries of amines, from urethane derivatives, we re 20-50% with HCl and 10-20% with H2SO4 (48 h); using alkaline condit ions it was 30-50% (4 h). For urea derivatives, the hydrolysis recover ies of amines were 25-35% for both HCl and H2SO4 and about 20-40% (48 h) for alkaline conditions. Losses of the free amines spiked in water and urine were observed using HCl or NaOH but much less using H2SO4. I ncreasing the hydrolysis time from 16 to 32 h did not result in an inc rease of more than 10% of the amount of amines relased. Decreasing the hydrolysis time to 8 h, decreased the amount of amines released by ab out 50%. Molecular sieve fractionation of plasma from workers showed t hat the dominating part of the biomarkers was bonded to macromolecules >10 kDa and in urine the biomarkers were bonded to molecules <5 kDa.