Optimization of the tube-plate method for determining the potency of neomycin sulphate
Objective To optimize the determination method of neomycin content,increase the diameter of the antibacterial ring in the tube disc method,and improve detection efficiency.Method According to the experimental requirements of Appendix 1200 Antibiotic Microorganisms(Assay Method)in the 2020 edition of the Chinese Veterinary Pharmacopoeia,different bacterial concentrations(0.5,1,2,3,and＞4 mcf),medium pH(7.8,8.0,8.2,and 8.4),and NaCl addition ratios(0,3％,4％,5％,7％,and 9％)in phosphate buffer were selected based on the indicators,such as diameter of the antibacterial zone and confidence limits.Results The results showed that under the conditions of adding 0.5％of the bacterial solution with a concentration of 3 mcf of Staphylococcus aureus,a culture medium pH of 8.0,and adding 5％NaCl to the buffer,the diameter of the antibacterial zone expanded to about 20 mm,and the edge of the antibacterial zone was clear.The confidence limit rate met the requirements of the Veterinary Pharmacopeia of the People's Republic of China(not more than 5％).This condition was stable and reliable,and it had been verified through actual samples from multiple products and manufacturers.Conclusion The optimized method can be used for the determination of conventional potency content of neomycin.
NeomycinAntibiotic microbial assay methodDetermination of potencyStaphylococcus aureus
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