title: Determination of pK(a) values of a triptolide derivative and its impurities by pressure-assisted capillary electrophoresis.
abstract: A pressure-assisted capillary zone electrophoresis method was developed to determine the pKa values of a triptolide derivative (LLDT-246) and its impurities. The method was performed in an uncoated fused-silica capillary under the electric voltage of 18kV and 50mbar of external pressure applied simultaneously. A series of running electrolyte buffers were used with pH ranging between 2.2 and 10.0 with the constant ionic strength of 0.05M. The values of pKa of LLDT-246 and two impurities were calculated based on the pH dependence of effective mobilities (μeff). The pKa value of LLDT-246 was in good agreement with that of determined by potentiometric titration method.
authors.affiliation: Laboratory of Pharmaceutical Analysis, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, PR China.
authors.forename: Jian-Ling
authors.initials: JL
authors.lastname: Wang
authors.forename: Xue-Jiao
authors.initials: XJ
authors.lastname: Xu
authors.forename: Dong-Ying
authors.initials: DY
authors.lastname: Chen
mesh_terms: D001331:Automation; D002021:Buffers; D002626:Chemistry, Pharmaceutical; D004224:Diterpenes / Q000032:analysis / Q000737:chemistry*; D015195:Drug Design; D004563:Electrochemistry; D004573:Electrolytes; D019075:Electrophoresis, Capillary / Q000379:methods*; D004852:Epoxy Compounds / Q000032:analysis / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007166:Immunosuppressive Agents / Q000032:analysis; D007477:Ions; D008956:Models, Chemical; D009994:Osmolar Concentration; D010616:Phenanthrenes / Q000032:analysis / Q000737:chemistry*; D010936:Plant Extracts / Q000032:analysis; D011312:Pressure; D029757:Tripterygium / Q000378:metabolism
chemical_list: D002021:Buffers; D004224:Diterpenes; D004573:Electrolytes; D004852:Epoxy Compounds; D007166:Immunosuppressive Agents; D007477:Ions; D010616:Phenanthrenes; D010936:Plant Extracts; C001899:triptolide
keywords: Capillary electrophoresis; External pressure; Impurities; Potentiometric titration; Triptolide derivative; pK(a)