Selective densitometric determination of four alpha-aminocephalosporins using ninhydrin reagent

A simple, selective, and precise densitometric method for analysis of four alpha-aminocephalosporins, namely cefaclor monohydrate, cefadroxil monohydrate, cefalexin anhydrous, and cefradine anhydrous, both in bulk drugs and in formulations was developed and validated. The method employed thin-layer chromatography (TLC) aluminium sheets precoated with silica gel G 60 F(254) as the stationary phase. The solvent system consists of ethyl acetate-methanol-water with different ratios for all studied drugs (R(f) values of 0.40-0.60). The separated spots were visualized as blue to violet color after spraying with ninhydrin reagent. The linear regression analysis data for the calibration plots of all studied drugs produced a good linear relationship with correlation coefficients ranging from 0.9990 to 0.9996 and coefficients of determination ranging from 0.9986 to 0.9992 over the concentration range 2-10 microg/spot. The limits of detection and quantitation for all studied drugs ranged from 0.09 to 0.23 and from 0.27 to 0.84 microg/spot, respectively. The developed method was applied successfully for the determination of the studied drugs in their pharmaceutical dosage forms with good precision and accuracy. Also, the method can be employed as a promising stability-indicating assay.