Crystallization Selectivity of Ribavirin Solution and Amorphous Phase.

Crystallization selectivity is an important principle in polymorph control. Ribavirin Form I, Form II, DMSO solvate, and amorphous ribavirin are prepared, and the short-range order similarities between these solid forms and ribavirin aqueous solution and DMSO solution are compared via mid-frequency Raman difference spectra (MFRDS). The crystallization process from amorphous ribavirin to Form I and from solution to amorphous phase is explained. Reasons for the difficulty in preparing the DMSO solvate are proposed. The rationale provided for the crystallization selectivity provides a foundation for the synthesis of metastable phases with a robust and convenient method.

Biomineralization and Properties of Guanine Crystals.

Guanine crystals with unique optical properties in organisms have been extensively studied and the biomineralization principles of guanine are being established. This review summarizes the fundamental physicochemical properties (solubility, tautomers, bands, and refractivity), polymorphs, morphology of biological and synthetic forms, and the reported biomineralization principles of guanine (selective recrystallization of amorphous precursor, preassembled scaffolds, additives, twinning, hypoxanthine doping, fluorescence, and assembly). The biomineralization principles of guanine will be helpful for the synthesis of guanine crystals with excellent properties and the design of functional organic materials for drugs, dyes, organic semiconductors, etc.

Detection of galactooligosaccharides with high lactose interference in infant formula using a simple single epimer chromatography.

Robust and more anti-interference enzymatic quantification of galactooligosaccharide (GOS) is important in consumer protection. However, many methods with harsh conditions could hardly separate GOS's hydrolysates galactose from its structurally similar isomer glucose, since each of them has double epimers, especially to determinate a trace of GOS from large amounts of lactose in the food matrix. The investigation was designed to solve the problem by using High Performance Liquid Chromatography with Evaporative Light Scattering Detector (HPLC-ELSD), applying friendly mobile phase and column. Result showed the content of galactose was seldom affected even by a high content of glucose by integrating the peak area of an excellent resolution single epimer. Moreover, the method existed a good linearity and stability (recovery rate at 90.5-105.1%), which met the statutory limit requirement for the quantitative analysis of concentrated GOS in infant formula. It was also helpful for separating and quantifying other sugar or epimers.