SPECTROPHOTOMETRIC DETERMINATION OF BINARY MIXTURE OF SOME Β-LACTAM ANTIBIOTICS

Derivative spectrophotometric techniques (first, second, third and fourth derivative) were developed for the determination of four β-lactam antibiotic binary mixtures; in combinations containing these compounds. The simultaneous determination of these compounds was accomplished by derivative (^1D,^ 2D, ^3D and ^4D) spectrophotometric technique and applying zerocrossing technique amoxiclline trihydrate with cephalexin monohydrate (mix I) using ^1D spectrum zero crossing at valley 238.2 nm, and ^2D spectrum at valley 263.8 nm, respectively, amoxiclline trihydrate with cloxacillin sodium (mix II) using ^2D at valley 281 and ^4D at valley 230.6, respectively, cephalexin monhydrate with cloxacillin sodium (mix III) using ^1D spectrum zero crossing at 272 nm and ^2D spectrum at 253.2 nm, respectively and ampicillin trihydrate with cloxacillin sodium (mix IV) using 1D at 282nm and ^2D at 271.6 nm, respectively. From this studying it was noticed that in all the applications of the previous methods the correlation coefficient of calibration curves not less than 0.999 and the relative standard deviation not exceed to 0.214. The four described procedures were successfully applied to the determination of these compounds in synthetic mixtures and in preparations with high percentage of recovery, accuracy and precision .The procedures do not require any separation step.