S.M. Al-Ghannam


This paper describes two simple, sensitive and selective spectrophotometric and atomic absorption spectrometric (AAS) procedures for the determination of two compounds of cephalosporins (Cephalexin monohydrate and Cephradine). These procedures are based on the formation of ion-pair complexes between the drugs and ammonium reineckate. The formed precipitates are quantitatively determined either spectrophotometrically or by AAS procedures. The methods consist of reacting drugs with Reinecke's salt in an acidic medium at a temperature of 25 ± 2°C. The spectrophotometric procedure (procedure I) is based on dissolving the formed precipitate with acetone. The volume was completed quantitatively and absorbance of the solution was measured at 525 nm against blank. Also, the AAS procedures (procedure II) are quantitatively determined directly or indirectly through the chromium precipitate formed or the residual unreacted chromium in the filtrate at 358.6 nm. The optimum conditions for precipitation have been carefully studied. Beer's law is observed for the studied drugs in the ranges 0.1-1.5 mg mL-1 or 5-70 μg mL-1 using spectrophotometric or AAS methods, with correlation coefficients ≥ 0.9965, respectively. Both procedures I and II were accurate and precise when applied to the analysis of the cited cephalosporins in different dosage forms with good recovery percent ranged from 98.90 ± 0.94 to 100.15 ± 0.97 without interference from additives.