Heart-cutting two-dimensional liquid chromatography coupled to quadrupole-orbitrap high resolution mass spectrometry for determination of N,N-dimethyltryptamine in rat plasma and brain; Method development and application

A new two-dimensional liquid chromatography method coupled to high-resolution tandem mass spectrometry was developed to measure the level of N,N-dimethyltriptamine (DMT) in rat plasma and brain tissue. The method achieved high recovery (90% in plasma, 88% in brain) and sensitivity (limit of detection 0.108 ng/mL in plasma, 0.212 ng/g in brain) within a 10-minute run. In an experimental model of cerebral ischemia/reperfusion, DMT concentration in rat plasma before hypoxia (49.3–114.3 ng/mL) was generally higher than after hypoxia (10.6–96.1 ng/mL). After treatment, brain DMT levels rose to 2–6.1 ng/g. The approach reliably detects and confirms DMT administered therapeutically.

Study at a glance

Abstract

The orthogonal heart-cutting liquid chromatography (LC) modes coupled to high-resolution tandem mass spectrometry (HRMS/MS) provide a number of possibilities to enhance selectivity and sensitivity for the determination of targeted compounds in complex biological matricies. Here we report the development of a new fast 2D-LC-(HRMS/MS) method and its successful application for quantitative determination of the level of plasma and brain N,N-dimethyltriptamine (DMT) using α-methyltryptamine (AMT) as internal standard in an experimental model of cerebral ischemia/reperfusion using DMT administration. The 2D-LC separation was carried out by a combination of hydrophilic interaction liquid chromatography (HILIC) in the first dimension followed by second-dimensional reversed-phase (RP) chromatography within a total run time of 10 min. The enrichment of HILIC effluent of interest containing DMT was performed using a C18 trapping column. During method development several parameters of sample preparation procedures, chromatographic separation and mass spectrometric detection were optimised to achieve high DMT recovery (plasma: 90 %, brain: 88 %) and sensitivity (plasma: 0.108 ng/mL of LOD, brain: 0.212 ng/g of LOD) applying targeted analytical method with strict LC and HRMSMS confirmatory criteria. Concerning rat plasma sample, the concentration of DMT before hypoxia (49.3-114.3 ng/mL plasma) was generally higher than that after hypoxia (10.6-96.1 ng/mL plasma). After treatment, the concentration of DMT in brain was elevated up to the range of 2-6.1 ng/g. Overall, our analytical approach is suitable to detect and confirm the presence of DMT administered to experimental animals with therapeutic purpose in a reliable manner.