Abstract
The feasibility for separation of positional isomers using capillary electrochromatography (CEC) was investigated. Two groups of neutral isomers, trifluoroacetophenone and bromobenzonitrile, were separated by CEC. Effects of selected parameters, such as mobile phase pH, ionic strength, temperature, organic modifier, buffer type, diluent type, voltage, and column length, were studied using bromobenzonitrile isomers to elucidate the separation mechanisms. In parallel, the separation of the isomers was also performed by high-performance liquid chromatography (HPLC) to serve as a comparison. It was found that the retention time behavior as a function of acetonitrile concentration in CEC was similar to that observed in HPLC. The effect of mobile phase pH has a greater impact with CEC than with HPLC due to the change in electroosmotic flow. The effect of temperature with liquid chromatography showed a linear Van't Hoff plot, while deviations from linearity were noted with CEC. The optimized CEC method was validated in terms of linearity, limit of detection, and injection precision. The experimental results indicate that the separation of positional isomers by CEC is feasible and is an appropriate alternative technique to reverse phase HPLC.
Published Version
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