Objective To quantify the contents of baicalin, wogonoside, baicalein, wogonin, chrysim and oroxylinA in the Scutellaria baicalensis Georgi with different storage time by liquid chromatography-mass spectrometry( LC-MS) and determine the stability of Scutellaria baicalensis Georgi. Methods The LC system consisted of an Agilent Zorbax XDB-C18 column (2. 1 mm×150 mm,3. 5 μm) with acetonitrile and water (0. 1% formic acid) in linear gradient condition. The flow rate was 0. 2 mL·min-1 and the wavelength of detection was 276 nm. The mass spectrometer was operated under the positive ion mode with the ESI source. The precursor-to-product ion pair was 447/271 for baicalin,461/285 for wogonoside,271/123 for baicalein, 285/270 for wogonin, 255/153 for chrysim and 285/270 for oroxylinA, respectively. Results The contents of baicalin, wogonoside, baicalein, wogonin, chrysim and oroxylin A had a linear relationship with their peak areas within the ranges of 8. 86-177. 2, 2. 33-46. 5, 2. 6-52. 0, 0. 52-10. 4, 0. 04-0. 8 and 0. 04-0. 8 μg · mL-1 , respectively. The contents of baicalin, wogonoside, baicalein, wogonin, chrysim, and oroxylin A were overall decreased over the first 3 months of storage,but remained relatively stable between 0 and 18 months. Conclusion The results provides basis for the establishment of quality standard.

OBJECTIVE： To study effective component kinds and content difference of Scutellaria baicalensis with different harvesting periods collected in spring and autumn， and to determine the optimal harvesting time. METHODS： IR-IL was used to analyze the constitutions change of the components in S. baicalensis collected in different harvesting periods （annual， biennial and triennial， in spring and autumn， respectively）. HPLC-MS method was used to analyze the contents change of 6 flavonoids （qroxylin A， chrysin， wogonin， wogonoside， baicalin， baicalein）. RESULTS： Results of IR-TL analysis showed that S. baicalensis contained different components such as flavonoids， glycosides， saccharides， easters in different growth stages， among which the contents of glycosides in biennial S. baicalensis were the highest with more stable quality. The results of content determination of 6 flavonoids showed that different harvesting periods had a great influence on the contents of the above indicators. The overall content of biennial samples collected in spring was higher than that of autumn samples collected in the same year. CONCLUSIONS： This study provides a reliable analytical method for the quality control of S. baicalensis； spring harvest in two-year growth period may be the best harvesting time for S. baicalensis.