Porous and non-porous stationary phases for capillary electrochromatography under conditions of reversed phase chromatography

The preparation and evaluation of packed columns for CEC with porous and non-porous stationary phases with particle diameters between 1.5 μm and 5 μm is described. They are compared with respect of achievable efficiency, magnitude of EOF, dependence on buffer pH and concentration as well as on organic modifier content. No general correlation between chromatographically measured surface silanol concentration and magnitude of EOF could be found. Problems in reproducibility of retention in CEC may arise from in-column heat generation and overloading problems. The strong dependence of column efficiency on volume overloading is demonstrated. The use of peak area measurements for quantitative analysis is recommended. The application of CEC to the separation of herbicides and DNPH derivatives is demonstrated.