Determination of naphthalene metabolites in human urine by liquid chromatography-mass spectrometry with electrospray ionization.

The use of a liquid chromatography-electrospray mass spectrometry system was investigated for the quantitative analysis of naphthalene metabolites (alpha-naphthol, alpha-naphthylglucuronide and beta-naphthylsulphate) in untreated urine samples. Chromatography was carried out under ion-suppressed reversed-phase conditions, by using high-speed (3 cm, 3 microns) columns and formic acid (2 mM) as a modifier in the mobile phase. The ionization was obtained in the negative-ion mode. Linearity, sensitivity and precision of the method were explored by operating in selected-ion monitoring mode. The method was applied to the quantitative analysis of naphthalene metabolites in untreated urine samples from workers in a naphthalene producing plant. Solid-phase extraction was used for sample clean-up and trace enrichment. Liquid chromatography-tandem mass spectrometry experiments were performed for confirmation purposes.