Separation and Characterization of a New Isomeric Impurity in Cefalotin Sodium by HPLC and MEKC

Abstract

A micellar electrokinetic chromatography (MEKC) method was developed for the determination of impurities in cefalotin sodium. The optimized separation is performed with the background electrolyte composed of 25 mM sodium tetraborate buffer (pH 9.2) containing 0.2 M sodium dodecylsulfate and an applied voltage of 30 kV in a bare fused-silica capillary (50 µm i.d. × 64.5 cm, 56 cm detection length). The method was validated in terms of linearity, accuracy, precision, robustness, limit of detection, and limit of quantification. Analyzing the commercial cefalotin sodium and cefalotin sodium CRS with the novel MEKC method, a new impurity was detected in the range of 0.67–1.48% level along with the potential known impurities, which was co-eluted with the main product in the pharmacopoeia high-performance liquid chromatography systems. The new impurity was confirmed to be 3-positional isomer of cefalotin by synthesis, 1H-NMR spectrometry, and MEKC techniques.