SAMPLE MATRIX EFFECTS IN MICELLAR ELECTROKINETIC CAPILLARY ELECTROPHORESIS

Several factors related to sample matrix which can influence peak heig ht in micellar electrokinetic capillary chromatography were studied. T he ionic strength of the sample did not affect greatly the peak height . High concentration of surfactants or organic solvents in the sample decreased the peak height. On the other hand, using a surfactant in th e sample different from the one in the electrophoresis buffer or the a ddition of polyethylene glycol to the sample enhanced slightly the pea k height. A high surfactant concentration in the buffer increased the migration time as well as the plate number and the peak height. Matrix effects are more profound with large than with small sample injection s. In general, the effect of sample matrix in MECC is much less than t hat observed in capillary zone electrophoresis. It is recommended to p repare the standards in the same matrix as that of the sample or to ad d the analytes directly to the sample to avoid any bias in the results .