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Determination of dissociation constants of ten alkaloids by capillary zone electrophoresis
Author(s) -
Gong Suxuan,
Su Xiaodan,
Bo Tao,
Zhang Xu,
Liu Huwei,
Li Ke An
Publication year - 2003
Publication title -
journal of separation science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.72
H-Index - 102
eISSN - 1615-9314
pISSN - 1615-9306
DOI - 10.1002/jssc.200390075
Subject(s) - capillary electrophoresis , chemistry , oxymatrine , matrine , chromatography , dissociation constant , alkaloid , tetrandrine , ionic strength , nonlinear regression , analytical chemistry (journal) , linear regression , dissociation (chemistry) , electrophoresis , stereochemistry , regression analysis , organic chemistry , receptor , biochemistry , machine learning , aqueous solution , computer science , medicine , pathology
The dissociation constants of ten alkaloids, berbamine, (+)‐tetrandrine, thalifaretine, thalifaricine, northaltive, matrine, sophocarpine, sophoridine, oxymatrine, and oxysophocarpine isolated from herbal medicines Thalictrum and Sophora flavescens , were determined by capillary zone electrophoresis (CZE). The analysis time for each alkaloid was within 10 min under the following experimental conditions: acetate (pH 3.81–5.55) and phosphate buffer (pH 6.05–9.29) with ionic strength set at 0.03, applied voltage 30 kV, UV detection at 210 nm, capillary temperature 25°C. Effective mobility for each alkaloid and corresponding pH were fitted to an equilibrium expression by using nonlinear regression as well as linear regression, showing that the two models give comparable results for all studied alkaloids. The correlation coefficients were between 0.987 and 1.00 in the linear regression model, and between 0.978 and 1.00 in the nonlinear model. The measured p K a values for the ten alkaloids were from 5.7 to 7.8. The p K a values changed with the addition of organic additive to the buffer system.