毛细管区带电泳法测定3种香豆素的离解常数

摘要

Capillary zone electrophoresis ( CZE ) is applied to the determination of dissociation constants of coumarin derivatives ( daphnin, daphnetin and umbelliferone ) . Capillary electrophoresis is an attractive method for pKa measurements, which is based on the migration time or mobilities of ionic species over a range of pH values. The pKa values of three cumarins is 7. 43(7-HC), 6. 91(DN) and 6. 86(DP). The method was validated by the comparison of results obtained by a traditional method, UV spectroscopy. No distinct difference was observed between the two methods. The CZE-UV method for pKa measurement shows good repeatability and reliability.%采用毛细管区带电泳法(CZE)测定瑞香苷(DN)、瑞香素(DP)和7-羟基香豆素(7-HC)的离解常数(pKa).通过测试不同酸度条件下各香豆素的迁移时间，以香豆素在电泳中有效淌度和运行液中OH-浓度的关系，推导了毛细管区带电泳-紫外分光光度( CZE-UV)法测定3种香豆素离解常数( pKa)的线性模型，并建立了这3种香豆素的pKa测定方法.测得3种香豆素的pKa值分别是7.43(7-HC)、6.91(DN)和6.86(DP).同时也采用传统方法-紫外分光光度法对这些物质的pKa进行测定以验证CZE的可靠性，两种测定结果相一致，说明CZE-UV法用于3种香豆素的离解常数的测定，快速、简便、结果可靠.