Development of a liquid chromatography/tandem mass spectrometry method for monitoring of long-term exposure to parabens.

Abstract

Parabens, the alkyl esters of 4-hydroxybenzoic acid, are a family of compounds widely used as preservatives in cosmetic products, including for children, and some are permitted in foods. Parabens are known to be weak endocrine disruptors because they interfere with the function of endogenous hormones through binding to estrogen receptors. Therefore, the levels of parabens in biological samples indicate endocrine-disruptive exposure. In particular, hair samples can provide information on accumulated exposure to parabens. For monitoring of long-term exposure to parabens, an improved analytical method for rapid and direct determination in hair sample was developed involving ultra-performance liquid chromatography-tandem mass spectrometry using on-line extraction. Five parabens (methyl-, ethyl-, propyl-, butyl- and benzylparaben) were separated within 10 min after incubation with 1 N HCl. Parabens were separated using a Waters BEH C18 column (2.1 mm × 100 mm, 1.7 μm) and a mobile phase consisting of 10 mM ammonium acetate in water and acetonitrile with a gradient program at a flow rate of 300 μL/min. The analysis of the separated parabens was monitored with electrospray negative ionization tandem mass spectrometry. The linearity of the method was demonstrated by r2 ≥0.994. The limits of detection as defined by a signal-to-noise ratio of 3 were 1-5 ng/g. The mean concentration of the five parabens in hair of human subjects was measured to be 55.6 ± 24.3 to 136.9 ± 48.5 ng/g. The levels of parabens in hair samples may play an important role in understanding probable endocrine-disruptive exposure, and the described method could be used to evaluate and monitor long-term exposure to parabens as endocrine disruptors.