Abstract:

Objective To establish the ultra-performance liquid chromatography-tandem mass spectrometry （UPLC-MS/MS） method to detect ethanol metabolites phosphatidylethanol （PEth） in whole blood. Methods An appropriate amount of aqueous solution including 1% formic acid was added to 100 μL whole blood, the protein was precipitated with acetone, centrifuged and the supernatant was purified and enriched by using Bond Elut Certify column. The eluent was redissolved with 1/1 isopropanol/acetonitrile （v/v） solution after nitrogen blowing and then tested by UPLC-MS/MS. Selective reaction monitoring scanning was carried out in negative ionization mode, and quantitative analysis was performed by external standard method. Results PEth showed a linear relationship over the concentration range of 1-160 ng/mL in whole blood （r=0.999 9） with peak area. The detection limit was 0.2 ng/mL, the quantification limit was 1 ng/mL, the recovery rate was 97.43%-103.61%, the accuracy was 0.99%-1.77%, the intra-day precision was 0.4%-2.4%, and the inter-day precision was 1.1%-3.3%, and the matrix effect was 91.00%-99.55%. PEth was not detected in the in vitro blood samples supplemented with ethanol. PEth was detected positive in three drunk driving cases, and the concentration were 195.49， 83.67 and 876.12 ng/mL, respectively. Conclusion The established method has high sensitivity and specificity and the analysis results are accurate. It is suitable for the qualitative and quantitative analysis of PEth in whole blood.

Key words: forensic toxicology, ethanol biomarker, phosphatidylethanol, solid phase extraction, ultra-performance liquid chromatography-tandem mass spectrometry （UPLC-MS/MS）