title: Simultaneous determination of propofol and its glucuronide in whole blood by liquid chromatography-electrospray tandem mass spectrometry and the influence of sample storage conditions on the reliability of the test results.
abstract: Propofol (2,6-diisopropylphenol) is commonly used as an anaesthetic agent but is also abused for recreational purposes. Several cases of fatalities involving self-administered propofol have been reported. For rapid quantification of propofol and propofol β-d-glucuronide (propofol G) in clinical and forensic cases, an ultra-performance liquid chromatography-tandem mass spectrometry method using pneumatically assisted electrospray ionisation has been developed. The technique has been validated on both ante-mortem and post-mortem human whole blood. The proteins in the blood samples were removed by the addition of a mixture of methanol and acetonitrile, and the extract was cleaned up by solid phase extraction. The extract was concentrated in dimethyl sulphoxide. The system was calibrated using matrix-matched calibrants combined with isotope dilution. The lower limits of quantification were 0.01 and 0.02mg/L for propofol and 0.02 and 0.04mg/L for propofol G in ante-mortem and post-mortem whole blood, respectively. The relative intra-laboratory reproducibility standard deviation was less than 10% at concentrations of 0.2mg/L or higher. The mean true extraction recovery was 85% for propofol and 81% for propofol G. The trueness of the propofol determination expressed as the relative bias of the test results was within ±6% at concentration levels of 0.01-8.5mg/L. Propofol was less stable in blood stabilised with a citrate-EDTA-fluoride mixture than in blood stabilised with an oxalate-fluoride mixture. The stability was lower at -20°C than at 5°C and -80°C. Propofol G did not show instability under the storage conditions tested.
authors.affiliation: Section for Forensic Chemistry, Department of Forensic Medicine, Aarhus University, Brendstrupgaardsvej 100, 8200 Aarhus N, Denmark. Electronic address: lks@forensic.au.dk.
authors.forename: Lambert K
authors.initials: LK
authors.lastname: Sørensen
authors.affiliation: Section for Forensic Chemistry, Department of Forensic Medicine, Aarhus University, Brendstrupgaardsvej 100, 8200 Aarhus N, Denmark.
authors.forename: Jørgen B
authors.initials: JB
authors.lastname: Hasselstrøm
mesh_terms: D018686:Anesthetics, Intravenous / Q000097:blood*; D002138:Calibration; D002851:Chromatography, High Pressure Liquid; D020719:Glucuronides; D006801:Humans; D057230:Limit of Detection; D015742:Propofol / Q000097:blood*; D015203:Reproducibility of Results; D013048:Specimen Handling; D021241:Spectrometry, Mass, Electrospray Ionization; D015813:Substance Abuse Detection; D053719:Tandem Mass Spectrometry
chemical_list: D018686:Anesthetics, Intravenous; D020719:Glucuronides; D015742:Propofol
keywords: Blood; LC–MS/MS; Propofol; Propofol glucuronide; Stability