Simultaneous Quantification of Propofol and its Non-Conjugated Metabolites in Several Biological Matrices Using Gas Chromatography/Ion Trap – Mass Spectrometry Method

Abstract

Propofol is an important compound used for anaesthetic purposes in clinical practice. Nevertheless, in the recent years, the use of propofol has also been reported for recreational, abusive or even for suicidal and criminal purposes. So far, there is a lack of practical techniques validated for simultaneous quantification of propofol and its non-conjugated metabolites (2,6-diispropyl-1,4-quinol and 2,6-diispropyl-1,4-quinone) in plasma and organs, to optimize therapeutics, to prevent undesired effects, and for application in forensic settings. A simple gas chromatography/ Ion trap – mass spectrometry method was optimized for the detection and quantification of propofol and its non-conjugated metabolites in plasma and organ (liver, heart, kidney and lungs) samples. All compounds were simultaneously extracted from 0.5 mL of plasma and 0.2 g of each organ, following a straightforward and rapid procedure using thymol as internal standard. This method was validated according to international guidelines for analytical methods. The standard curve ranged from 0.005 to 100 μg/mL for propofol and 0.005 to 50 μg/mL for the non-conjugated metabolites. Intra and inter-assay variability for propofol and its metabolites was less than 15% and the average recovery was greater than 90%. The proof of applicability of this methodology allowed the successful measurement of propofol and its non-conjugated metabolites in plasma and solid tissues from seven New Zealand White rabbits that were submitted to a long-term anaesthesia protocol with a continuous infusion of propofol ranging from 20 to 60 mg/kg/h. This optimized and validated assay may also be suitable in the monitoring of sedated or anaesthetised animals and humans with continuous infusions of propofol and for use in pharmacokinetic and toxicological studies.