As large quantities of antibiotics have been misused in human and veterinary medicine, many different classes of antibiotics with low concentration have been detected in the environmental water. This existence may cause severe ecosystem alterations. Ceftriaxone sodium was employed as the targeted antibiotic to evaluate gamma radiolysis of antibiotics based on the primary elimination test and activity assay. The decomposition percentage of ceftriaxone sodium (20 µg/ml) in purified water increases with increasing doses and reaches 98% under 5 kGy of gamma radiation. The residual activity after gamma radiation does not follow the corresponding decomposition percentage of ceftriaxone sodium. Liquid chromatography and mass spectrometry (LC-MS) was subsequently employed to analyze possible structures of radiolytic products relating to the activity. Different degrees of the residual activity may attribute to different cleavage pathways of ceftriaxone sodium produced by radiation with different doses. The results indicate that the radiolytic treatment is a highly-effective means for degradation of ceftriaxone sodium, and the activity status of ceftriaxone sodium after primary elimination should be taken into consideration for selecting a degrading dose. Three kGy is the appropriate dose for radiolysis of ceftriaxone sodium in purified water.
Keywords: activity, antibiotics, ceftriaxone sodium, gamma radiation, LC-MS, water treatment