Open Access Research Article Analytical & Bioanalytical Techniques Campos et al., J Anal Bioanal Tech 2014, 5:3 http://dx.doi.org/10.4172/2155-9872.1000195 Volume 5 • Issue 3 • 1000195 J Anal Bioanal Tech ISSN: 2155-9872 JABT, an open access journal Keywords: Propofol; Propofol non-conjugated metabolites; Propofol method validation Introduction he drug, propofol (2,6-diisopropylphenol), is an intravenous anaesthetic which arose from the family of alkylphenols and showed to have sedative-hypnotic properties in animals [1,2] and in humans [3,4], by interacting with GABA receptors [5]. Propofol acquired great acceptation worldwide being extensively used for induction and maintenance of anaesthesia in human and veterinary practice. Moreover, propofol has been given in lower doses to critically ill patients for stabilization and titratable sedation in intensive care units (ICU) [6]. Since it is known to produce mild euphoria and hallucinations, the use of propofol for recreational purposes has been an issue. Furthermore, many deaths have occurred due to its abuse and misuse [7]. Some case reports are available in literature related to suicides by using propofol alone or in mixtures [8,9]. Propofol has a rapid and extensive biotransformation into multiple non-conjugated and conjugated metabolites. he non- conjugated metabolites result from propofol ring hydroxylation (CYP P450) and consist in two inter-conversable isomers: 2,6-diisopropyl- 1,4-quinol and 2,6-diisopropyl-1,4-quinone (Figure 1). As for propofol, they can be found in the blood stream (plasma and serum) and organ tissues and are suspected to have one third of propofol hypnotic activity [10,11]. Furthermore, the infusion of propofol in higher doses and for long periods has been associated with a rare but potentially fatal set of clinical and toxicological features in critically ill patients: Propofol Infusion Syndrome (PRIS). his syndrome has already been described in humans [3,12], rabbits [13] and dogs [14]. he onset mechanism of this syndrome is not well understood but the non-conjugated metabolites of propofol may be implied as trigger compounds *Corresponding author: Sónia Campos, REQUIMTE – Toxicological Laboratory, Biological Science Department, Faculty of Pharmacy, University of Porto, Rua Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal, Tel: +351 22 0428000 (ext. 8796); E-mail: soniapatcampos@gmail.com Paula Guedes de Pinho, REQUIMTE – Toxicological Laboratory, Biological Science Department, Faculty of Pharmacy, University of Porto, Rua Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal, Tel: +351 22 0428000 (ext. 8796); E-mail: pguedes@ff.up.pt Received May 27, 2014; Accepted June 30, 2014; Published July 02, 2014 Citation: Campos S, Monteiro J, Antunes L, Branco PS, Ferreira LM, et al. (2014) Simultaneous Quantification of Propofol and its Non-Conjugated Metabolites in Several Biological Matrices Using Gas Chromatography/ Ion Trap – Mass Spectrometry Method. J Anal Bioanal Tech 5: 195 doi:10.4172/2155-9872.1000195 Copyright: © 2014 Campos S, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract Propofol is an important compound used for anaesthetic purposes in clinical practice. Nevertheless, in the re- cent 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 quantiication 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 quanti- ication 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 straight- forward 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. Simultaneous Quantification of Propofol and its Non-Conjugated Metabolites in Several Biological Matrices Using Gas Chromatography/Ion Trap – Mass Spectrometry Method Sónia Campos 1,2 *, Joaquim Monteiro 3 , Luís Antunes 1 , Paula S Branco 4 , Luísa M Ferreira 4 , Luís Félix 1 and Paula Guedes de Pinho 2* 1 CITAB - Centro de Investigação e de Tecnologias Agro-Ambientais e Biológicas, University of Trás-os-Montes and Alto Douro, Quinta de Prados, 5001-801 Vila Real, Portugal and LAS - Institute of Molecular and Cell Biology, Porto, Rua do Campo Alegre, nº 823, 4150-180 Porto, Portugal 2 REQUIMTE – Toxicological Laboratory, Department of Biological Sciences, Faculty of Pharmacy, University of Porto, Rua Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal 3 CESPU, Institute of Research and Advanced Training in Health Sciences and Technologies, Department of Pharmaceutical Sciences, Higher Institute of Health Sciences (ISCS-N), Rua Central de Gandra 1317, 4585-116, Gandra PRD, Portugal 4 REQUIMTE - Department of Chemistry, Faculty of Science and Technology, University Nova of Lisbon, Campus de Caparica, 2829-516 Caparica, Portugal