ESR identification of irradiated antibiotics: cephalosporins

The ESR technique was tested as a tool to detect antibiotics irradiated for sterilization purposes. Thirteen different cephalosporins, each commercially available, were given a sterilization dose of 25 kGy and then studied by ESR. For 12 out of the 13 samples tested, a specific radiation-induced signal was detected whose time stability allows identification tests. For one cephalosporin (cefaclor), the same signal is present in the irradiated and unirradiated samples. However, identification is still possible due to the high radiation-induced radical concentration and favorable signal time stability.