Influence of perfluorinated carboxylic acids on ion-pair reversed-phase high-performance liquid chromatographic separation of betacyanins and 17-decarboxy-betacyanins.
The ability of trifluoroacetic acid, pentafluoropropionic acid and heptafluorobutyric acid to act as ion-pairing agents for betacyanins and 17-decarboxy-betacyanins during HPLC analysis on a Luna C18(2) reversed-phase column is reported. While the perfluorinated carboxylic acids affect the retention of both groups of compounds by changing the pH of the mobile phase, the possibility of ion-pair chromatography for 17-decarboxy-betacyanins was noticed. In order to explain the accessibility of the positive charge for the counter-anion in decarboxy-betacyanins, the mesomeric structures of the polymethine system at low pH (around a value of 1.5), when the carboxylic group in the 2 position is protonated, should be taken into consideration.
Wybraniec
Sławomir
S
Department of Chemical Engineering and Technology, Institute C-1, Faculty of Analytical Chemistry, Cracow University of Technology, ul. Warszawska 24, Cracow 31-155, Poland. swybran@chemia.pk.edu.pl
Mizrahi
Yosef
Y
D050858:Betalains; D002264:Carboxylic Acids / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D007477:Ions; D010860:Pigments, Biological / Q000302:isolation & purification*; D000644:Quaternary Ammonium Compounds
D002264:Carboxylic Acids; D007477:Ions; D010860:Pigments, Biological; D000644:Quaternary Ammonium Compounds; D050858:Betalains