DETERMINATION OF 4,4'-METHYLENEDIPHENYLDIANILINE (MDA) AND IDENTIFICATION OF ISOMERS IN TECHNICAL-GRADE MDA IN HYDROLYZED PLASMA AND URINE FROM WORKERS EXPOSED TO METHYLENE DIPHENYLDIISOCYANATE BY GAS-CHROMATOGRAPHY MASS-SPECTROMETRY

Gas chromatography-mass spectrometry using chemical ionization with am monia as reagent gas monitoring both positive and negative ions was ap plied. Negative-ion monitoring using ammonia and the pentafluoropropio nic anhydride (PFPA) derivatives were chosen owing to low detection li mits and good separation for the isomers studied. Technical-grade meth ylenediphenyldiioscyanate (MDI) was analysed and three isomers, 4,4'-, 2.4'- and 2,2'-methylenediphenyldianiline (MDA), were determined in a ddition to methylated MDA. Plasma and urine from an exposed worker wer e hydrolysed and analysed and the MDA isomers were identified in the b iological samples.