Validation of a CE assay for the analysis of isomeric aminopyridines and diaminopyridines.

A capillary electrophoresis assay for the analysis of aminopyridines and diaminopyridines has been developed and validated. The compounds were separated using a 100 mM sodium acetate buffer at pH 5.15, an applied voltage of 20 kV and a capillary of 60 cm effective length, N-(1-naphthyl)ethylenediamine was used as internal standard to compensate for injection errors and minor fluctuations of the migration times. The detection wavelength was set at 240 nm and not optimized for a specific derivative. The assay was validated with respect to specificity, linearity, range, limit of quantitation and detection, precision, and robustness. Within certain limits, the assay also allowed the detection and determination of the other aminopyridine derivatives at the 0.1% level as demonstrated for 3,4-diaminopyridine.