DETERMINATION OF TOLUENEDIAMINE ISOMERS BY CAPILLARY GAS-CHROMATOGRAPHY AND CHEMICAL-IONIZATION MASS-SPECTROMETRY WITH SPECIAL REFERENCE TOTHE BIOLOGICAL MONITORING OF 2,4-TOLUENE AND 2,6-TOLUENE DIISOCYANATE

The determination of 2,3-, 3,4-, 2,6-, 2,4- and 2,5-toluenediamine (TD A) in hydrolysed human urine and blood plasma was studied by GC-MS. Th e TDA isomers as their perfluoro-fatty acid anhydride derivatives were investigated. Chemical ionization with ammonia and isobutane as reage nt gas and monitoring both positive and negative ions are studied. Neg ative ion monitoring using ammonia and the TDA pentafluoropropionic an hydride (PFPA) derivatives were chosen owing to the low detection limi ts and good separations of the isomers studied. The ions monitored wer e m/z 394 and 374 corresponding to the (M - 20)(-) and (M - 40)(-) ion s and the m/z = 397 and 377 ions of the trideuterium-labelled TDA used as an internal standard. The performance of 2,4-, 2,5- and 2,6-TDA-PF PA in the ion source was studied by varying the ammonia pressure, temp erature and electron energy. A 1-ml volume of human urine was added to 1.5 ml of 6 M HCl containing 0.5 mu g/l of each of the trideuterated 2,6- and 2,4-TDA and the solution was hydrolysed at 100 degrees C over night. TDA was extracted into 2 mi of toluene by the addition of 5 ml of saturated NaOH solution. Derivatization was performed in toluene by the addition of 10 mu l of PFPA. The excesses of the reagent and acid formed were removed by extraction with 1 M phosphate buffer solution (pH 7.5). Analyses of 2,6-, 2,4- and 2,5-TDA-spiked human urine (0.2-2 .5 mu g/l) were performed. The correlation coefficients were 0.999 (n = 6). The precision (R.S.D.) for human urine spiked at 1 mu g/l was 1. 6% for 2,6-TDA, 3,5% for 2,4-TDA and 3.2% for 2,5-TDA (n = 10). The de tection limit, defined as twice the signal-to-noise ratio, was 1-5 fg injected, corresponding to less than 0.05 mu g/l of TDA in human urine or plasma.