High-Performance Liquid Chromatographic Determination of Cefalexin Monohydrate and Kanamycin Monosulfate with Precolumn Derivatization

Abstract

A liquid chromatographic method for the determination of cefalexin monohydrate and kanamycin monosulfate in their synthetic binary mixture was developed and validated according to ICH guidelines. Cefalexin monohydrate and kanamycin monosulfate both contain primary amine and were derivatized with phenylisocyanate in presence of triethylamine at 70°C for 10 min forming corresponding N-aryl-N′-phenyl urea derivative. The separation was achieved on Phenomenex column, C18, 250 × 4.6 mm, 5 µm under isocratic conditions, using acetonitrile: 1% tris buffer (40:60 v/v) pH adjusted to 6.5 with 1 N sulfuric acid, as a mobile phase and flow rate was 1.0 mL/min. The retention times were 3.7 and 8.5 min for cefalexin monohydrate and kanamycin monosulfate, respectively, at 242 nm. The linear concentration range was 7.5–22.5 µg/mL for cefalexin monohydrate and 5–15 µg/mL for kanamycin monosulfate. The mean percentage recoveries for binary mixture were found to be 93.33–99.11 for cefalexin monohydrate and 92–98 for kanamycin monosulfate. The pooled % RSD value for validation parameters for both the methods was less than 2. The results of method confirm that this high-performance liquid chromatographic method can be applicable, for quality control and assay of bulk and binary synthetic mixture.