An optimized method for neurotransmitters and their metabolites analysis in mouse hypothalamus by high performance liquid chromatography-Q Exactive hybrid quadrupole-orbitrap high-resolution accurate mass spectrometry.

Neurotransmitters (NTs) and their metabolites are known to play an essential role in maintaining various physiological functions in nervous system. However, there are many difficulties in the detection of NTs together with their metabolites in biological samples. A new method for NTs and their metabolites detection by high performance liquid chromatography coupled with Q Exactive hybrid quadruple-orbitrap high-resolution accurate mass spectrometry (HPLC-HRMS) was established in this paper. This method was a great development of the applying of Q Exactive MS in the quantitative analysis. This method enabled a rapid quantification of ten compounds within 18min. Good linearity was obtained with a correlation coefficient above 0.99. The concentration range of the limit of detection (LOD) and the limit of quantitation (LOQ) level were 0.0008-0.05nmol/mL and 0.002-25.0nmol/mL respectively. Precisions (relative standard deviation, RSD) of this method were at 0.36-12.70%. Recovery ranges were between 81.83% and 118.04%. Concentrations of these compounds in mouse hypothalamus were detected by Q Exactive LC-MS technology with this method.

An optimized method for corticosterone analysis in mouse plasma by ultra-performance liquid chromatography-full-scan high-resolution accurate mass spectrometry.

A simple method based on liquid chromatography-full-scan high-resolution accurate mass spectrometry (LC-HRMS) using a quadrupole time-of-flight (TOF) mass spectrometry was developed and optimized for corticosterone quantification in mouse plasma. Mouse plasma (100 µL) was extracted with methyl tert-butyl ether using prednisone as internal standard. Separation was performed on a short C18 column using a methanol-water gradient. Full-scan data were acquired in the TOF only mode, and extracted ion chromatograms were generated post-acquisition with the extract masses of the analytes. Enhanced sensitivity and reproducibility were acquired with optimized mass parameters. The calibration range was 8.24-412 ng/mL, and the limit of quantitation was 5.088 g/mL. Accuracy was between -5.9 and 8.6%. The precision of between-run (interday) and within-run (intraday) was within 5.6 and 6.9%, respectively. The LC-HRMS method was applied for plasma samples analysis from the stressed mice with and without ginseng treatment for the stress state estimation.