Simultaneous Determination of Aromatic Isocyanates and Some Carcinogenic Amines in the Work Atmosphere by Reversed-Phase High-Performance Liquid Chromatography

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Abstract
A reversed-phase high-performance liquid chromatographic method with UV-detection is described for the simultaneous determination of aromatic isocyanates and some carcinogenic aromatic amines which may be present together in the work atmosphere of the polyurethane industry. The air is sampled through ethanol which is made alkaline by potassium hydroxide (KOH). The isocyanates react instantaneously to the corresponding ethyl urethanes, while the amines remain in nonionized state. KOH, which has been added to catalyze the ethyl urethane reaction and eliminate the side reactions, is precipitated out with hydrochloric acid and the sample solution is evaporated to dryness. The residue is dissolved in 1 ml ethanol and water (1:1). A 50-ul aliquot of the resulting solution is chromatographed on a Rad Pak C18 column and eluted isocratically with a mixture of tetrahydrofuran, acetonitrile and water buffered with acetate to some exact value in the pH range 5.5–7.0. The use of this pH range is favored both by the retention behaviour and UV-detectability of the aromatic amines.