Pages : 56 – 63
Chand Pasha and B. Narayana
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 104 Lmol-1 cm-1 for cefotaxime, 1.23 x 105 Lmol-1 cm-1 for ceftriaxone, 6.91 x 104 Lmol-1 cm-1 for cefadroxil, and 4.08 x 104 Lmol-1 cm-1 for cefalexin. The method has been successfully applied to the determination of cefotaxime, ceftriaxone, cefadroxil and cefalexin in various pharmaceutical samples.