Salting-out-assisted liquid–liquid extraction as a suitable approach for determination of methoxetamine in large sets of tissue samples
Kateřina Hájková, Bronislav Jurásek, David Sýkora, Tomáš Páleníček, Petra Mikšátková, Martin Kuchař
Analytical and Bioanalytical Chemistry December 11, 2015 DOI: 10.1007/s00216-015-9221-1 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Method development and validation study Peer reviewed |
|---|---|
| Population | Rat brain, liver, and lung tissues |
| Keywords | Analyte Sample preparation Homogenization climate Matrix chemical analysis Extraction chemistry Liquid chromatography–mass spectrometry Electrospray Selected reaction monitoring Analytical chemistry journal Tandem mass spectrometry |
| Citations | 26 |
| Key points | A sample preparation and LC-MS method using salting-out-assisted liquid-liquid extraction can reliably quantify MXE and its five metabolites in rat brain, liver, and lung tissues with good recovery and minimal matrix effects. |
Abstract
A new designer drug, a dissociative anesthetic, and a putative N-methyl-D-aspartate receptor antagonist, methoxetamine (MXE) noted by the EU Early Warning System has been already identified as a cause of several fatalities worldwide. The primary objective of this work was to develop a suitable sample preparation method allowing for isolation of MXE and its main metabolites in high yields from rat brain, liver, and lungs. For the purpose of the project, MXE and five metabolites were synthesized in-house, specifically O-desmethyl-normethoxetamine, O-desmethylmethoxetamine, dihydro-O-desmethylmethoxetamine, normethoxetamine, and dihydromethoxetamine. A sample preparation procedure consisted in the homogenization of the tissue applying salting-out-assisted liquid-liquid extraction (SALLE). A subsequent liquid chromatography-mass spectrometry (LC-MS) analysis was based on reversed-phased chromatography hyphenated with a triple quad MS system in a positive electrospray mode. Multiple reaction monitoring (MRM) was used for qualification and quantification of the analytes. The quantification was based on the application of an isotopically labeled internal standard, normethoxetamine-d3. The matrix-matched calibrations were prepared for each type of matrix with regression coefficients 0.9943-1.0000. The calibration curves were linear in the concentration range of 2.5-250 ng g(-1). Limits of quantification (LOQs) were estimated as 2.5 and 5 ng g(-1), respectively. Recovery (80-117%) and matrix effect (94-110%) at 100 ng g(-1) and intra- and inter-day accuracy and precision at low (2.5 ng g(-1)), middle (25 ng g(-1)), and upper (250 ng g(-1)) concentration levels for all the analytes in all three types of tissues were also determined. The developed analytical method was applied to a set of real samples gathered in toxicological trials on rats and MXE, and its metabolites were determined successfully.