An integrated strategy for the systematic chemical characterization of Salvianolate lyophilized injection using four scan modes based on the ultra-high performance liquid chromatography-triple quadrupole-linear ion trap mass spectrometry.

Salvianolate lyophilized injection (SLI), a freeze-dried powder injection derived from aqueous extract of S. miltiorrhiza, is therapeutically used to treat the syndrome of blood stasis and collateral blockage during the recovery period after stroke. To date, it has remained a significant challenge to comprehensively characterize the compounds of SLI, particularly the minor components with potential bioactivities, in one sample injection analysis. Using an integrative four scan modes approach coupled with ultra-high performance liquid chromatography-triple quadrupole-linear ion trap mass spectrometry (UHPLC-QTRAP-MS/MS), we propose a novel, sensitive, and simple strategy for systematic and rapid profiling of the chemical components of SLI. First, an in-house database of constituents from the water-soluble extract of Danshen was created. Second, the fragmentation behaviors of the representative components in SLI were obtained using the untargeted scan mode enhanced MS (EMS)-information dependent acquisition (IDA)-enhanced product ion (EPI). The specific fragments acquired were then utilized to conduct precursor ion (Prec) and neutral loss (NL)-IDA-EPI scans. Following that, a sensitive predictive multiple reaction monitoring (pMRM)-IDA-EPI scan method with 454 transitions was developed based on the prominent fragment ions and plausible predictions. A total of 171 compounds were tentatively identified from SLI. Among them, 27 minor components have not been previously reported. This strategy allows most isomeric compounds at trace levels to be readily distinguished and annotated. Finally, 15 batches of 13 representative components in SLI selected by the qualitative results were accurately quantified. Salvianolic acid A (Sal A), Sal B, Sal D, lithospermic acid (LA), and rosmarinic acid (RA) were proved to be the predominant constituents. Sal B had the highest amount (195.08-350.46 μg·mg), followed by LA, Sal A, Sal D, and RA. Moreover, these 15 batches of samples showed good uniformity, and no abnormal batches existed. These results suggest that this novel strategy can accelerate the identification of undiscovered chemical components and serve as an alternative method for in-depth profiling of compounds in other traditional Chinese medicines (TCMs).