Ion chromatography on a new moderate capacity anion exchange column

The mechanisms of retention of anions on a new solvent-compatible, moderate capacity (170 microequivalent per column) anion-exchange column are described. Retention based on anion exchange is shown using both sodium hydroxide and 4-cyanophenolate eluants. Plots of the log k' vs. log C, (where k' is the capacity factor and C is the eluant concentration) are shown to be linear with slopes approximating the charge of the eluant as predicted by the standard anion-exchange equation. Sodium hydroxide is shown to be a relatively weak eluant, capable of separating monovalent anions that are difficult to separate on other columns. Sodium 4-cyanophenolate is shown to be a strong eluant, capable of eluting polyvalent anions. The retention of nonionic alkylphenones is also described. In plots of log k' vs. percentage acetonitrile in the eluant, these compounds were found not to follow the solvophobic mechanism typical of reverse-phase HPLC columns. Results are compared with other anion exchange columns. Applications include the determination of lysophosphatidyl inositol in brain microsomes and methacrylic acid in esterase-treated samples.