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Use of solid phase microextraction in tips (SPME-Tips) for analysis of cocaine and biotransformation products in oral fluid by liquid chromatography tandem mass spectrometry (LC-MS / MS)

Grant number: 20/11848-4
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): November 01, 2020
Effective date (End): June 30, 2021
Field of knowledge:Health Sciences - Pharmacy - Toxicological Analysis
Principal researcher:José Luiz da Costa
Grantee:Leonardo Costalonga Rodrigues
Home Institution: Faculdade de Ciências Farmacêuticas (FCF). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
Associated research grant:17/02147-0 - Single drop chromatography and its coupling to mass spectrometry: instrumental strategies, development of materials, automation and analytical applications, AP.TEM

Abstract

The analysis of psychoactive substances has undergone several improvements in recent years, such as the use of alternative biological matrices likeoral fluid, which is noteworthy for being an alternative matrix with several advantages, such as simplicity and non-invasive collection, the difficulty of adulteration, the low level of risk of contamination and the possibility of detecting recent use. The drugs most commonly identified in this matrix include THC, opioids and cocaine. According to the 2019 United Nations Office on Drugs and Crime World (UNODC) report, in recent years, nearly two million users have used cocaine in the U.S. and Europe. Cocaine is rapidly biotransformed, producing mainly benzoylecgonine and methylecgonine. Cocaetylene is formed in the concomitant use of cocaine with ethanol and anhydroecgonine methyl ester (AEME) is produced by pyrolysis in the use of crack. Cocaine determination, according to some studies, is effective in oral fluid, as this substance appears in saliva shortly after intravenous administration. Several traditional extraction techniques are reported in the literature, however, such methods use high amounts of organic and sample solvents, in addition to involving several steps and consuming significant time. To counteract such problems, microextraction techniques have been proposed and, among them, solid phase microextraction (SPME), deserves mention. Solid phase microextraction is a technique based on green chemistry principles, since it works without the use of organic solvents, besides being more economical. In addition, this microextraction technique reduces the analysis time and uses smaller sample volumes. A variation of the SPME technique was recently developed and consists of the use of fiber tips (SPME Tips), coated with HPLC-type silica. In this technique, analytes are retained in reverse phase, which allows the tip to be directly immersed in biological fluids, such as oral fluid, causing the analytes to be adsorbed on the fiber and allowing desorption to be carried out with solvents. The advantages of SPME with the use of fiber tips are operational simplicity, ease of automation, low volume of organic solvents used, low sample consumption and minimization of interference. Few articles in the literature describe the use of SPME Tips, none of which use SPME Tips for the analysis of cocaine, benzoylecgonine, methylecgonine, AEME and cocaethylene in oral fluid. This work aims to develop and validate a method for the analysis of cocaine and its biotransformation products using the SPME-Tips technique and liquid chromatography tandem mass spectrometry (LC-MS/MS). The developed method can be used for laboratory diagnosis of intoxications caused by these toxic agents. The SPME Tips extraction procedure will be optimized during the development stage. After optimization, the experimental procedure developed will be validated in accordance with SGWTOX recommendations and should use a small volume of oral fluid and organic solvents, in accordance with current green chemistry proposals.

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