Study on simultaneous determination methods for anions by capillary electrophoresis

Simultaneous determination methods for anions were studied by capillary electrophoresis (CE). First, a CE method for the analysis of inorganic and organic anions which have UV absorbance was developed by using a polymer-coated capillary. Next, CE methods for anions having little or no UV absorption were described. Each method was performed with indirect UV detection using 2,6- pyridinedicarboxylic acid (PDC) and cetyltrimethylammonium salt as the background electrolyte (BGE). To avoid the adsorption of organic acids on the capillary, high complexing ability with metals was necessary for the BGE. The use of PDC provided a good sensitivity of organic acids. 28 carbohydrates, such as acidic, neutral, amino sugars and sugar alcohols, could be analyzed with the same BGE at a pH of 12.1. Its utility was demonstrated in an analysis of monosaccharides of hydrolyzed glycoprotein and food samples. The high complex ability of PDC also enabled the simultaneous analysis of inorganic and organic anions, as well as metal cations. The PDC worked to confer a negative charge on metal cations via PDC-complex formation. Furthermore, this BGE system was evolved into the simultaneous analysis of 43 inorganic anions, organic acids, amino acids and carbohydrates and applied to the analysis of those compounds in food samples.