Analysis of endocannabinoids in plasma samples by biocompatible solid-phase microextraction devices coupled to mass spectrometry

Author(s)

Acquaro Junior, Vinicius R. ^{[1, 2]} ; Gomez-Rios, German Augusto ^{[1, 3]} ; Tascon, Marcos ^{[1, 4]} ; Costa Queiroz, Maria Eugenia ^[2] ; Pawliszyn, Janusz ^[1]

Affiliation

^[1] Univ Waterloo, Dept Chem, Waterloo, ON N2L 3G1 - Canada

^[2] Univ Sao Paulo, Fac Filosofia Ciencias & Letras Ribeirao Preto, Dept Quim, Sao Paulo - Brazil

^[3] Restek Corp, Bellefonte, PA - USA

^[4] Univ Nacl San Martin UNSAM, 3iA, Buenos Aires, DF - Argentina

• Document type: Journal article
• Source: Analytica Chimica Acta; v. 1091, p. 135-145, DEC 24 2019.
• Web of Science Citations: 0

Abstract

Anandamide (AEA) and 2-arachidonoyl glycerol (2-AG) represent two of the most important endocannabinoids (ECs) investigated in neurobiology as therapeutic targets for several mental disorders. However, the determination of these ECs in biological matrices remains a challenging task because of the low concentrations, low stability and high protein-bound (LogP similar to 6). This work describes innovative analytical methods based on biocompatible SPME (Bio-SPME), SPME-UHPLC-MS/MS and Bio-SPME-Nano-ESI-MS/MS, to determine AEA and 2-AG in human plasma samples. The direct coupling of Bio-SPME with nano-ESI-MS/MS can be considered an alternative tool for faster analysis. Different Bio-SPME fibers based on silica and polymeric coating (i.e. C-18, C-30, and HLB) were evaluated. Different desorption solvents based on combinations of methanol, acetonitrile, and isopropanol were also evaluated for efficient elution with minimum carry-over. Given the high protein binding analytes and the fact that SPME extracts the free-concentration of the analytes, the plasma samples were modified with additives such as guanidine hydrochloride (Gu-HCl), trifluoroacetic acid, and acetonitrile. This study was carried out by experimental design to achieve complete protein denaturation and the release of target analytes. The maximum extraction efficiency was obtained under the following conditions: HLB coated fibers (10 mm length, 20 mu m coating thickness), matrix modified (300 mu L of plasma) with 50 mu L of Gu-HCL 1 mol L-1, 75 mu L of ACN and 75 mu L of water, and desorption with methanol/iso-propanol solution (50:50, v/v). Both methods were validated based on current international guidelines and can be applied for monitoring of concentrations of endocannabinoids in plasma samples. SPME-UHPLC-MS/MS method presented lower LOQ values than SPME-nanoESI-MS/MS. The additional separation (chromatographic column) favored the detectability of LC-MS/MS method. However, the SPME-nano-ESI-MS/MS decrease the total analysis time, due to significant reductions in desorption and detection times. (C) 2019 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 17/02147-0 - Single drop chromatography and its coupling to mass spectrometry: instrumental strategies, development of materials, automation and analytical applications
• Grantee: Fernando Mauro Lanças
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 16/16180-6 - Determination of AEA and 2-AG in plasma samples by Bio-SPME-Nano-ESI
• Grantee: Vinicius Ricardo Acquaro Junior
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate