INTER-COMPANY CROSS-VALIDATION EXERCISE ON CAPILLARY ELECTROPHORESIS - QUANTITATIVE-DETERMINATION OF DRUG COUNTERION LEVEL

A capillary electrophoresis (CE) method for the quantitative determination of sodium levels in the sodium salt of an acidic drug has been transferred across 6 independent pharmaceutical companies. All companies were able to demonstrate similar selectivity and acceptable precision for migration times and relative migration times. Five companies obtained acceptable precision for the repeatability of response factors from repeated injections of calibration solutions. Highly variable results from the sixth company indicated problems arising from contamination from residual sodium, possibly from unclean glassware or autosampler vials. The quantitative assay results from all companies confirmed the correct drug: counter-ion ratio. The average % w/w sodium content was 5.45% which represents 99.0% of the theoretical sodium content of sodium cephalothin