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@#The high-purity impurity C was isolated and purified from a new anti-allergic drug, rupatifen, by nucleophilic substitution reaction with bromobutaric acid, and its structure was confirmed by IR, UV, MS, 1H NMR, 13C NMR, DEPT135°,HSQC, HMBC, and 1H-1HCOSY. The preparation process of impurity C in this study was simple and easy to obtain under mild conditions, with the purity of 99.0% and the yield of 25%-30%;and the sample met the target compound by structural confirmation. The preparation process and structure confirmation provided sufficient impurity C reference substance for impurity research of raw materials and preparations of rupatifen fumarate, which laid a solid foundation for quality research of new drugs.
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OBJECTIVE: To establish the national reference standards of sulfadimidine impurities thus to provide guarantee for improving the standard of quality control of sulfadiazine in China. METHODS: First, the structures of sulfadimidine impurities A and E were validated by infrared spectrocopy, mass spectrum and nuclear magnetic resonance method. Then, the purities of impurities A and E were determined using the method of related substance test for sulphadiazine in the European Pharmacopoeia (version 9.0),their water content and residue on ignition were determined as well. The contents of sulfadimidine impurities A and E were determined by using mass balance method. Meanwhile, external standard method and nuclear magnetic quantitative method were used to calculate the content, which were mutually verified with the mass balance method. Finally, the correction factors of sulfadiazine impurities A and E at 241 nm were determined using standard curve method. RESULTS: The structures of sulfadimidine impurities A and E were confirmed, and the contents of impurities A and E were 99.1% and 98.7%, respectively, which were calculated by mass balance method. The results were consistent with those obtained from external standard method and nuclear magnetic quantification method. The correction factors of impurities A and E to sulfadimidine were 0.97 and 0.63, respectively. CONCLUSION: The first batch of national standard substances of sulfadimidine impurities A and E were established successfully.
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OBJECTIVE: To confirm the structures of the impurities of cefatrizine propylene glycolate.
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OBJECTIVE: To explore the sources and structures of the main impurities in compound tilidine hydrochloride oral solution.
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OBJECTIVE: To study the impurity of pentoxifylline and glucose injection and confirm its structure and source. METHODS: LC-MS was used to speculate the structure of the impurity. The impurity was synthesized by using theobromine and 1, 3-di-bromopropane as the starting materials and the structure was identified by IR, LC-MS, 1H-NMR, and 13C-NMR. RESULTS: The impurity was identified to be 1, 1′-(propane-1, 3-diyl)bis(3, 7-dimethyl-3, 7-dihydro-1H-purine-2, 6-dione). CONCLUSION: The study provides theoretical basis for the control of impurity in the production process and quality assessment of pentoxifylline and glucose injection.
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OBJECTIVE: To prepare impurity C in benzathine benzylpenicillin products. METHODS: Using the mother liquor of benzathine benzylpenicillin, impurity C was prepared by means of vacuum distillation, column chromatography, and recrystallization. Its molecular structure was confirmed with UV, IR, MS, NMR and elemental analysis. Its purity and correction factor were determined by HPLC method. The contents of impurity C in the samples were determined by external standard method. RESULTS: The prepared product was proved to be impurity C by structure confirmation. CONCLUSION: The preparation of impurity C in benzathine benzylpenicillin products has important significance for the control of related substances of benzathine benzylpenicillin products.