Résumé
The high performance liquid chromatography [HPLC] enantioseparation of four p-blocking agents metoprolol. bisoprolol, propranolol and atenolol was performed on amylose tris-[3.5-dimethylphenylcarbamate] chiral stationary phase using n-hexane-ethanol-diethylamine [DBA] as the mobile phase and related chiral recognition mechanisms were discussed. Enantiomeric separation of the four beta-blockers was a result of more than one type of interaction between solutes and CSP. Besides hydrogen bonding, there was another type interaction that was independent of solvent polarity and responsible for enantiomeric selectivity, such as interactions. Both the groups close to the chiral centers and the substituent groups on the phenyl rings, which were far away from the chiral centers, could contribute to the good separation. The separations of the four p-blocker enantiomers were all enthalpy driven process. In the range of 293-308K [20-35 °C]. as the temperature increased, the retention as well as the resolution decreased. The molecular size rather than concentration of the alcohol modifiers affected the resolution and retention
Résumé
0.990 0) with an average recovery ranged from 86.1% to 109.0%.The injection RSD were within 0.84%～3.1%(n=6).CONCLUSIONS:The method is successfully applied for simultaneous determination of 22 kinds of free amino acids.
Résumé
AIM:The polysaccharides of Hedyotis difusa Willd of different sources were extracted and its content and composition of the polysaccharide was analyzed. METHODS: The microwave was employed for the aqueous extract of Hedyotis difusa Willd and the content of total sugar was determined by phenol-sulfur test,the monosaccharides composition was determined by HPLC with pre-column derivatization. RESULTS: The polysaccharide obtained from the samples of Guangdong Province had the highest content.The analytic data showed that the composition of monosaccharides in hydrolytic polysaccharides of Hedyotis difusa Willd were mannose,glucose,galactose,arabinose and rhamnose,the average content of polysaccharides was 9.82%. CONCLUSION: The HPLC method with pre-column derivatization is appropriate for the analysis of monosaccharide composition of Hedyotis difusa Willd polysaccharides and the method is simple,quick and accurate.