Optimization of Secondary Chemical Equilibria in Liquid Chromatography: Variables Influencing the Self-Selectivity, Retention, and Efficiency in Acid–Base Systems

Abstract

The effects of several chromatographic variables on the self-selectivity (K′ AX/K′A), retention, and efficiency In secondary chemical equilibria liquid chromatography (SCE-LC) are reported. The self-selectlvitles were measured for numerous lonogenic compounds using pH-buffered mobile phases. Only the type of stationary phase employed affected the self-selectivity by more than a factor of 2. Data from the plots used to measure the self-selectlvitles are Included and serve as additional verification of the SCE-LC retention model discussed in the preceding paper. Solute retention can be varied without affecting the overall chromatographic selectivity by changing the amount of organic solvent added to the aqueous mobile phase or the chain length of the stationary phase. Column efficiency can be Improved by factors of 3–15 by adding small amounts of organic solvent to the aqueous mobile phase; this does not significantly affect the selectivity. When ≥4% 1-propanol Is used, the resulting efficiencies are equal to those obtained In conventional liquid chromatography. An approach for the optimization of resolution Is summarized. © 1987, American Chemical Society. All rights reserved.