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pKa determination of oxysophocarpine by reversed - phase high performance liquid chromatography

Huiling Huo12, Tingting Li1 and Lei Zhang1*

Author Affiliations

1 College of Chinese Traditional Medicine, Guangzhou University of Traditional Chinese Medicine, 232 East of Waihuan Road, University Town, Guangzhou, Guangdong 510006, R.P. China

2 College of Chinese Traditional Medicine, Southern Medical University, Guangzhou, Guangdong 510515, R.P. China

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SpringerPlus 2013, 2:270  doi:10.1186/2193-1801-2-270

Published: 20 June 2013



In this study, a RP - HPLC method was applied for determination of pKa value by using the dependence of the capacity factor (k) on the pH of the mobile phase for oxysophocarpine (OSP).


The effect of the mobile phase composition on the ionization constant was studied by measuring the pKa value at different MeOH concentrations, ranging from 10 to 20% (v/v). Based on all pH - k curves plotted and pH values at inflection point calculated, experimental pKa value obtained for oxysophocarpine was 6.5.


This method was successfully applied to realize low sample consumption, rapid sample throughput, high sensitivity and precision.

Oxysophocarpine; pKa value; HPLC