Objective To establish a method for determining the amount of silicone oil on the surface of rubber closures,which is one of the packaging material standards in the Pharmacopoeia of the People's Republic of China.Methods The development process of the method for determining silicone oil content on the surface of rubber closures was described,taking the infrared transmission mode as example.Through method validation,the scientific and rational aspects of the method were examined.Key points of the determination method were analyzed,including the selection of quantitative peaks,selection of measurement solvent,selection of extraction solvent and conditions,selection of instrument measurement methods,selection of liquid cell windows for infrared transmission mode,selection of quantification methods,and selection of dimethyl silicone oil reference standards.Results The infrared spectroscopy mode was chosen to determine the amount of polydimethylsiloxane on the surface of rubber closures based on the peak height of the Si-CH3 bond vibration absorption at 1 260 cm-1.Cyclohexane was used as the measurement solvent.The same concentration of polydimethylsiloxane reference solution was measured using both infrared transmission mode and attenuated total reflection mode,and quantification was performed based on peak height.The results from the two measurement modes were essentially the same.The linear range of polydimethylsiloxane was about 0.3-10.0 mg·mL-1,and its correlation coefficient was 0.999 8.The average recovery of the method was 102.3%-105.6%.The LOD of polydimethylsiloxane was 0.1 mg·mL-1.The silicone oil measurement results of seven batches for rubber closures were consistent with the silicone oil amounts provided by the manufacturer.Conclusion Enterprises can choose either the infrared transmission mode or the attenuated total reflection mode to measure the amount of polydimethylsiloxane on the surface of rubber closures based on their actual conditions.

Medical polyurethanes have emerged as a leading choice for biomedical applications owing to their exceptional biocompatibility and good physical and mechanical properties.Catalysts play a crucial role as additives in the synthesis of medical polyurethanes,enhancing synthesis efficiency and material properties.However,the catalysts used may affect the biocompatibility of polyurethanes and pose potential harm to human health.This review encapsulates the latest findings regarding the catalysts employed in the synthesis of medical polyurethane materials and their biotoxicity.Initially,we reviewed the prevalent types of catalysts used in the synthesis of medical polyurethane materials and described their distinctive characteristics.Subsequently,our focus shifted to exploring the potential biotoxicity associated with these catalysts.Finally,we provided a forward-looking perspective and recommendations for the future trajectory of catalyst selection in the synthesis of medical polyurethane materials.By acquiring a more profound understanding of the properties and biotoxicity of catalysts used in the synthesis of medical polyurethane materials,and by uncovering existing issues and challenges,we can better guide the design of medical polyurethane materials.This,in turn,enables us to chart the course for future development and ultimately enhance the biocompatibility and safety profiles of medical polyurethane materials.Such advancements will promote the continued development and application of medical polyurethane materials in clinical settings.