1. In-tube solid-phase microextraction directly coupled to tandem mass spectrometry for anandamide and 2-arachidonoylglycerol determination in rat brain samples from an animal model of Parkinson's disease.
- Author
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Oliveira IGC, Souza ID, Nascimento GCD, Del Bel E, and Queiroz MEC
- Subjects
- Animals, Arachidonic Acids isolation & purification, Arachidonic Acids standards, Brain drug effects, Calibration, Chromatography, High Pressure Liquid, Endocannabinoids isolation & purification, Endocannabinoids standards, Glycerides isolation & purification, Glycerides standards, Hydrophobic and Hydrophilic Interactions, Male, Oxidopamine pharmacology, Polyunsaturated Alkamides isolation & purification, Polyunsaturated Alkamides standards, Rats, Rats, Wistar, Solid Phase Microextraction, Tandem Mass Spectrometry standards, Arachidonic Acids analysis, Brain metabolism, Endocannabinoids analysis, Glycerides analysis, Polyunsaturated Alkamides analysis, Tandem Mass Spectrometry methods
- Abstract
To evaluate the endocannabinoid system in an animal model of Parkinson's disease, in-tube solid-phase microextraction (in-tube SPME) was directly coupled to a tandem mass spectrometry (MS/MS) system for determination of the endocannabinoids anandamide (AEA) and 2-arachidonoylglycerol (2-AG) in rat brain samples. In-tube SPME-which consisted of a microtube of restricted access material (RAM) with a hydrophilic diol external surface and a hydrophobic octyl inner surface-efficiently excluded (up to 95%) macromolecules from the biological samples and selectively pre-concentrated the analytes. In-tube SPME parameters, such as sample volume, mobile phases, flow rate, and pre-concentration time, were evaluated to improve the extraction efficiency and throughput performance. The selectivity of the in-tube SPME and MS/MS (MRM mode) techniques allowed them to be directly coupled online, which dismissed the need for the chromatographic separation step. The in-tube SPME-MS/MS method was validated and shown to be linear from 6.0 to 30.0 ng mL
-1 for AEA and from 10.0 to 100.0 ng mL-1 for 2-AG; the intra- and inter-assay accuracy and precision were lower than 15%. Parallelism between the calibration curves constructed in the matrix and aqueous solution confirmed that there was no matrix effect. The method allowed endogenous concentrations of AEA and 2-AG to be determined in rat brain striatum from unilaterally 6-hydroxydopamine-lesioned animals. The concentrations of these endocannabinoids in striatum ipsilateral and contralateral to the lesion differed significantly (p<0.001)., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020. Published by Elsevier B.V.)- Published
- 2021
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