A combined analytical method for biological monitoring of arsenic, benzene and polycyclic aromatic hydrocarbons in human urine by liquid chromatography tandem mass spectrometry

An analytical method for the biomonitoring of arsenic, benzene and polycyclic aromatic hydrocarbons (PAHs) in human urine was developed using liquid chromatography tandem mass spectrometry (LC-MS/MS). The urinary metabolites of monomethylarsonic acid (MMAA), dimethylarsonic acid (DMAA), s-phenylmercapturic acid (S-PMA), and 1-hydroxypyrene (1-OHP) were selected as the corresponding marker compounds. After enzymatic deconjugation, 4 mL urine sample was extracted by 2 steps of solvent extractions. The 1-OHP was first extracted with n-hexane with 10% ethyl acetate, and MMAA, DMMA, and S-PMA were then extracted in a 2nd extraction/ back-extraction using chloroform/ammonium bicarbonate aqueous solution. The two extracts were mixed and analyzed by LC-MS/MS. The method was validated with spiked urine samples. The obtained linear ranges (r(2) > 0.99) of the urinary markers were 2-64 ng/mL MMAA, 1-64 ng/mL DMAA, 0.78-100 ng/mL S-PMA and 0.05-6.4 ng/mL 1-OHP. The measured accuracy (% Error) and precision (CV%) were -16.67 to 29.17% and 2.03-30.99% (3 spiked levels, 6 replicates), respectively. The method was applied to 10 real urine samples, and the presence of MMAA, DMAA, S-PMA and 1.0HP were clearly detected. The detected concentrations were BQL-8.38 ng/mL of MMAA, BQL-10.71 ng/mL of DMAA, BQL-2.55 ng/mL of SPMA, and BQL-0.17 ng/mL of 1-OHP, which were all consistent with the reported background levels.