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.
The orthogonal heart-cutting liquid chromatography (LC) modes coupled to high-resolution tandem mass spectrometry (HRMSMS) 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-(HRMSMS) 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 ischemiareperfusion 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 ngmL of LOD, brain 0.212 ngg 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 ngmL plasma) was generally higher than that after hypoxia (10.6-96.1 ngmL plasma). After treatment, the concentration of DMT in brain was elevated up to the range of 2-6.1 ngg. 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.