Detection of Related Substances and Preliminary Study on the Degradation Mechanism of Baicalein / 中国药房

ABSTRACT

OBJECTIVE:To establish a method for the separation and detection of related substances in baicalein,identify its structure and preliminarily explore the degradation mechanism. METHODS:HPLC was adopted to detect the baicalein,related impurities and forced destruction of degradation products in synthesis processthe column was ES Industries? FluoroSep-RP Phenyl with mobile phase of 0.3%formic acid-methanol-acetonitrile(gradient elution)at a flow rate of 1.0 mL/min,the detection wavelength was 275 nm,the column temperature was 10℃,and the injection volume was 10μL. LC-MS/MS was conducted to identify the related substances and conjecture degradation mechanismthe column was ES Industries? FluoroSep-RP Phenyl with mobile phase of 0.3%formic acid- methanol (gradient elution)at a flow rate of 1.0 mL/min,the detection wavelength was 275 nm,column temperature was 10℃,and the injection volume was 10μL;ion source was electrospray ion source,positive and negative ions,nebulizer pressure was 55 psi and the drying gas flow was 11 L/min,drying gas temperature was 350℃,capillary voltage was 4.0 kV,detection modes were full-scan first-order MS and selective ion full-scan second-order MS,scan ranges were m/z 100-1000 (first-order MS) and 50-500(second-order MS),ionization voltage was 80-135 eV,and the collision energy was 10-30 eV. RESULTS:The linear range of baicalein was 2.4-480μg/mL(r=0.9999);RSDs of precision,stability and reproducibility tests were lower than 2.0%;the limit of quantitation was 7.2 ng,the limit of detection was 2.4 ng. Baicalein was well separated with related substance and 3 major degradation products,the related substance was chemical synthesis precursor wood butterfly;the degradation products were 6,7-quinone derivatives and 7,8-quinone derivatives,which were isomers;oxidative degradation products were benzoic acid phenyl ester derivatives. CONCLUSIONS:The main mechanisms of alkali degradation and oxidative degradation of baicalein include pyran, reciprocal rearrangement and oxidation reaction;the established method is specific and sensitive,and can be used for the detection of related substances in baicalein.