Enantioseparation and quantitative analysis of three alkaloids in Rhizoma Corydalis by chiral LC-MS/MS

A chiral liquid chromatography-mass spectrometry (LC-MS/MS) approach was developed and verified for the first time in order to quantify the three alkaloids, namely tetrahydropalmatine (THP), tetrahydroberberine (THB) and tetrahydrocoptisine (THC) in Rhizoma Corydalis. Solid-phase extraction was used to prepare sample solution. Enantiomeric separation was obtained on a Chiralpak IC column using acetonitrile-water-ammonia (90:10: 0.1, v/v/v) as mobile phase. The detection was carried out in multiple reaction monitoring (MRM) mode with positive electrospray ionization source. Transitions of m/z 356.0→192.0, m/z 340.0→176.0 and m/z 324.1→176.0 were monitored for THP, THB and THC respectively. All calibration curves showed good linearity (r² ≥0.9994) within the test ranges. The lower limit of quantification (LLOQ) was 1.0 ng mL^-1 and 1.5 ng mL^-1 for (+)- and (-)-THP, 1.0 ng mL^-1 and 3.0 ng mL^-1 for (+)- and (-)-THB, 1.5 ng mL^-1and 1.8 ng mL^-1 for (+)- and (-)-THC, respectively. The precision, repeatability, and stability tests all meet the requirements. The average recoveries of the analytes ranged from 98.9 % to 101.3 %. Ultimately, the established method was successfully applied to the quantitative analysis of these alkaloid enantiomers extracted from Rhizoma Corydalis of different habitats.