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Investigation of the factors that induce analyte peak splitting in capillary electrophoresis
Author(s) -
Chen Xiaofeng,
Xie Jianping,
Li Cunhong,
Hu Zhide,
Chen Xingguo
Publication year - 2004
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.200401817
Subject(s) - analyte , capillary electrophoresis , chemistry , electrophoresis , electrolyte , aqueous solution , analytical chemistry (journal) , ionization , chromatography , solvent , ion , organic chemistry , electrode
Peak splitting has a detrimental effect on analyses by capillary electrophoresis. Many papers have reported it and several mechanisms have been proposed to explain the phenomenon. We investigated the electrophoretic behavior of an amphoteric analyte, levodopa, in phosphate buffer and observed a peak splitting phenomenon at moderate sample concentrations and under general analytical conditions, even without organic solvent. The dependence of effective mobility on pH was taken into account and p K a values of 2.30, 8.11, and 9.92 were obtained for levodopa. Then, we constructed pH‐dependent distribution diagrams of levodopa and phosphate species present in aqueous solution and proposed that the most relevant factors contributing to peak splitting are the presence of ionizable groups in the analyte molecule and the occurrence of ionization, yielding charged species which interacted with buffer electrolyte species in a definite pH range to form complexes. This result is different from those presented in the literature and broadens our understanding of amphoteric analyte peak splitting.