Improvement of an Ultra-High Liquid Chromatography-Tandem Mass Spectrometry Method for the Simultaneous Quantification of Eleven Amino-Polycyclic Aromatic Hydrocarbons in Human Urine

Abstract

Urinary amino-polycyclic aromatic hydrocarbons (amino-PAHs), which are the metabolites of nitro-polycyclic aromatic hydrocarbons (nitro-PAHs), commonly used as biomarkers to assess occupational exposure to nitro-PAHs, especially in populations exposed to diesel exhaust. The current methods used for the detection of urinary amino-PAHs, mainly based on liquid-liquid extraction, that could not cover a wide-range of nitro-PAHs. Furthermore, the problem of interference from isomeric compounds has not been sufficiently resolved. We developed a reliable UPLC-MS/MS method, that incorporating SPE pretreatment, used for the detection of 11 amino-PAHs in urine samples from workers exposed to nitro-PAHs. Briefly, urine samples were enzymatically hydrolyzed and purified using SPE extraction and analyzed with refined UPLC-MS/MS method. Effective separation of 11 amino-PAHs was achieved using reversed-phase HSS PFP columns and a gradient elution of 0.1% formic acid in water and acetonitrile. The improved MS/MS conditions achieved sufficient sensitivity using ESI positive ion mode, with LOQs ranging from 0.009 to 0.378 μg/L. The optimation of our improved method for linearity, accuracy, precision, and matrix effects was conducted by employing two isotopically labeled internal standards (1-Aminonaphthalene-d7 and 1-Aminopyrene-d9). The method enabled precise and accurate quantification of the 11 amino-PAHs, with CV < 11% and recovery rates between 82.0% and 106.9%. Our improved method offers a unique analytical approach that could be used for biomonitoring of workers exposed to diesel exhaust.

Keywords: UPLC-MS/MS, nitro-polycyclic aromatic hydrocarbons, amino-polycyclic aromatic hydrocarbons, diesel exhaust