APPLICATION OF DIFFERENTIAL SCANNING CALORIMETRY TO THE STUDY OF THERMAL STABILITY OF CEPHALOSPORINS IN SOLID STATE

The thermal decomposition stability of a series of cephalosporins was examined by differential scanning calorimetric (DSC) technique. The Kissinger's and Ozawa's equations were employed for the determination of kinetic parameters of the first step of thermal decomposition of cephalosporins. The results were in good agreement. The thermal stability decreased in the order: cephalexin>cephradine sodium>cephoperazone sodium>cefamandole nafate sodium>cephaloridine (δ-form) >ceftizoxime sodium>ceftriaxone sodium>cefsulodine>ceftazidime>cephalothin sodium>cefotaxime sodium>cefazoline sodium.Because of the absence of melting processes, it is impossible to evaluate calorimetrically the purity of the antibiotics examined. Nevertheless, the peak temperature of the first step of thermal decomposition may be useful in identifying and characterizing the compounds.