Identification, isolation, and characterization of impurities in sodium tanshinone IIA sulfonate

Six impurities in sodium tanshinone IIA sulfonate (STS) were observed by high performance liquid chromatography (HPLC) using DAD detector. One of the impurities, sodium tanshinone I sulfonate was reported in literature, other five impurities were unknown having not been reported previously. Initially, all the six impurities were identified by the liquid chromatography-mass spectrometry (LC-MS) data. After the recrystallization, enrichment and primary separation with silica column of the crude samples of STS, four imputies were isolated from the crude sample by preparative HPLC. Based on the spectral data (UV, MS, 1H NMR and ¹³C NMR), the structure of these impurities were characterised as, sodium methyl tanshinonate sulfonate (impurity I), sodium tanshinone I sulfonate (impuritiy II), sodium 1,2-dehydro tanshinone IIA sulfonate (impurity III) and sodium przewaquinone A sulfonate (impurity IV).