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SIMPLE SPECTROPHOTOMETRIC DETERMINATION OF SELECTED CEPHALOSPORINS USING THIONIN

Pages : 56 – 63

Chand Pasha and B. Narayana

Abstract:

A simple spectrophotometric method for the determination of cephalosporin antibiotics as pharmaceutical ingredient namely cefotaxime, ceftriaxone, cefadroxil and cefalexin using thionin is described. The method is based on the hydrolysis of β-Lactam ring of sodium hydroxide which subsequently reacted with potassium iodate in acidic medium to liberate iodine. The liberated iodine bleaches the violet color of thionin which measured at 600 nm. The decrease in absorbance is directly proportional to the concentration of  cefotaxime, ceftriaxone, cefadroxil and cefalexin. Beer’s law is obeyed in the range 0.5 – 6.4 µg mL-1, 0.4 – 5.2 µg mL-1. 0.8 – 4.2 µg mL-1 and 1.0 – 7.5 µg mL-1 for cefotaxime, ceftriaxone, cefadroxil and cefalexin respectively. The molar absorptivity wa found to be 7.21 x 10Lmol-1 cm-1 for cefotaxime, 1.23 x 10Lmol-1 cm-1 for ceftriaxone, 6.91 x 10Lmol-1 cm-1 for cefadroxil, and 4.08 x 10Lmol-1 cm-1 for cefalexin. The method has been successfully applied to the determination of cefotaxime, ceftriaxone, cefadroxil and cefalexin in various pharmaceutical samples.

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