Résumé
OBJECTIVE: To establish the detection technology of riboflavin polymorphism, and investigate the moisture sorption properties of riboflavin. METHODS: The two crystal forms of riboflavin were characterized by different analysis methods, such as powder X-ray diffraction method (p-XRD), differential scanning calorimetry method (DSC) and infrared spectrum method (IR). Dynamic vapor sorption (DVS) analysis was adopted to acquire moisture sorption dynamics of the two crystal forms. The influences of temperature, humidity and light on crystal transformation were explored. RESULTS: The crystal forms of two batches of riboflavin samples were identified as anhydrate I and monohydrate, respectively. The monohydrate could be obtained by recrystallizing in DM-SO. The monohydrate was hygroscopic, the number of crystal water may change at different relative humidities, and the moisture sorption dynamics of the monohydrate was greatly influenced by temperature. The anhydrate I was almost non-hygroscopic, and temperature hardly affected its moisture sorption dynamics. CONCLUSION: Characteristic data for riboflavin polymorphism are obtained, and the results show that anhydrate I is more stable than monohydrate. This study indicates that DVS could be used in studies on drug polymorphism.
Résumé
OBJECTIVE: To investigate the moisture sorption properties of chemical reference substances (CRSs) by using dynamic vapor sorption (DVS) analysis technology in order to establish the distribution conditions, packaging materials, and usages of national chemical reference substances. METHODS: DVS analysis was adopted to acquire the moisture sorption dynamic profiles of five chemical reference substances of different moisture sorption types to evaluate their moisture sorption trend and capacities under different humidities. RESULTS: According to moisture sorption dynamics, we can found the hygroscopicity of disodium etidronate, sodium aminosalicylate, valaciclovir hydrochloride, aspirin and bosentan, and we have given advices about how to use these CRSs and what kind of bottles they should be packed in. CONCLUSION: DVS analysis can be used to record moisture sorption data in real time and visually observe water-CRS interactions under different humidities, which is an important technology for guiding the establishment and distribution of CRSs.