Sensitive determination of trace urinary 3-hydroxybenzo[a]pyrene using ionic liquids-based dispersive liquid–liquid microextraction followed by chemical derivatization and high performance liquid chromatography–high resolution tandem mass spectrometry

• Urinary 3-OHBaP is a biomarker for assessing carcinogenic PAH exposure in human.
• IL-DLLME was used for trace 3-OHBaP enrichment the first time.
• Lowering environmental toxicity and increasing extraction efficiency.
• Chemical derivatization using dansyl chloride enhanced HPLC-HRMS/MS response.
• Method validation results demonstrated satisfactory analytical performance.

3-Hydroxybenzo[a]pyrene (3-OHBaP) is widely used as a biomarker for assessing carcinogenic benzo[a]pyrene exposure risks. However, monitoring urinary 3-OHBaP suffers from an insufficient sensitivity due to the pg/mL level in urine excretion. In this study, a sensitive method for determination trace urinary 3-OHBaP was developed, involving enzymatic hydrolysis of the glucuronide and sulfate conjugates, ionic liquids dispersive liquid–liquid microextraction (IL-DLLME) enrichment, derivatization with dansyl chloride and HPLC-HRMS/MS analysis in the positive ion mode. Using IL-DLLME makes the enrichment of trace 3-OHBaP very simple, time-saving, efficiency and environmentally-friendly. To enhanced HPLC-HRMS/MS response, an MS-friendly dansyl group was introduced to increase the ionization and fragmentation efficiency. The optimal IL-DLLME extraction parameters and derivatization reaction conditions were investigated. Good linearity was obtained over a concentration range of 0.6–50.0 pg/mL with correlation coefficients (r2) of 0.9918. The limit of detection (LOD) and limit of quantification (LOQ) values were 0.2 pg/mL and 0.58 pg/mL, respectively. The recoveries were 92.0 ± 4.2% with the intra-day and inter-day RSD values ranged from 2.2% to 3.8% and from 3.3% to 6.8%, respectively. The proposed IL-DLLME-Dansylation-HPLC-HRMS/MS method was successfully applied to determine urinary 3-OHBaP of non-occupational exposed smokers and nonsmokers.