DETERMINATION OF IMPURITIES IN REMOXIPRIDE BY CAPILLARY ELECTROPHORESIS USING UV-DETECTION AND LIP-DETECTION - PRINCIPLES TO HANDLE SAMPLE OVERLOADING EFFECTS

A capillary electrophoresis method for determination of remoxipride-re lated impurities was developed using a dynamically tetraalkylammonium- coated C-8 capillary. The shape of the overloaded principal peak was r egulated by substituting tetraalkylammonium ions of different size for sodium ions, thereby altering the conductivity in the background elec trolyte. An adequate separation of the compounds was obtained after ad dition of methyl-beta-cyclodextrin as structural selector in combinati on with a reversed electroosmotic flow. The detection level for the im purities was 0.05 % (w/w) with the Beckman Pace 2100 using UV-detectio n. The limit of detection was substantially improved for the fluoresce nt compound FLA 797 using a LIF-detector equipped with a He-Cd laser a s excitation source achieving detection levels below 0.0005 %.