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New aspects of buffering with multivalent weak acids in capillary zone electrophoresis: Pros and cons of the phosphate buffer
Author(s) -
Gebauer Petr,
Boček Petr
Publication year - 2000
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/1522-2683(20000801)21:14<2809::aid-elps2809>3.0.co;2-p
Subject(s) - phosphoric acid , electromigration , phosphate , chemistry , electrolyte , capillary electrophoresis , electrophoresis , hydroxide , tetrabutylammonium hydroxide , dissociation (chemistry) , buffer (optical fiber) , analytical chemistry (journal) , chromatography , inorganic chemistry , materials science , electrode , composite material , telecommunications , computer science , organic chemistry
Phosphate buffer is frequently used as background electrolyte in capillary electrophoresis. It can cover a broad range of pH due to the three dissociation constants (p K 1 = 2.0, p K 2 = 7.2, and p K 3 = 11.0) of phosphoric acid and because it is UV‐light transparent. This contribution brings a theoretical study of the analytical separation performance (sample window, regions of peak symmetry, regions of fronting and tailing peaks) of phosphate buffer, serving as a model of buffering with multivalent weak acids. The study is based on the use of peak shape diagrams and covers the pH range 2.55—11.43. New important general knowledge has been revealed that single multivalent weak acids mimic the performance of background electrolytes with multiple coanionic species for anionic analyses. It is shown that simple phosphate buffers prepared by mixing phosphoric acid and potassium hydroxide may exhibit up to two regions of symmetry, of fronting as well as of tailing zones, on the mobility scale inside the sample window. Moreover they may exhibit a „schizophrenic” region of enormous electromigration dispersion.