The various advantages of organic polymer monoliths, including relatively simple preparation processes, abundant monomer availability, and a wide application range of pH, have attracted the attention of chromatographers. Organic polymer monoliths prepared by traditional methods only have macropores and mesopores, and micropores of less than 50 nm are not commonly available. These typical monoliths are suitable for the separation of biological macromolecules such as proteins and nucleic acids, but their ability to separate small molecular compounds is poor. In recent years, researchers have successfully modified polymer monoliths to achieve uniform compact pore structures. In particular, microporous materials with pores of 50 nm or less that can provide a large enough surface area are the key to the separation of small molecules. In this review, preparation methods of polymer monoliths for high-per-formance liquid chromatography, including ultra-high cross-linking technology, post-surface modifica-tion, and the addition of nanomaterials, are discussed. Modified monolithic columns have been used successfully to separate small molecules with obvious improvements in column efficiency.

As a mono-sodium salt form of alendronic acid, alendronate sodium presents multi-level ionization for the dissociation of its four hydroxyl groups. The dissociation constants of alendronate sodium were determined in this work by studying the piecewise linear relationship between volume of titrant and pH value based on acid-base potentiometric titration reaction. The distribution curves of alendronate sodium were drawn according to the determined pKa values. There were 4 dissociation constants (pKa1=2.43, pKa2=7.55, pKa3=10.80, pKa4=11.99, respectively) of alendronate sodium, and 12 existing forms, of which 4 could be ignored, existing in different pH environments.

AIM: To study the effect of growth hormone (GH) and vitamin E (Vit.E) combined in the treatment of endometrial thinning. METHODS: Twenty female SD rats were randomly divided into four groups: control group, model group, GH group and treatment group, with 5 rats in each group. Control group was routinely fed; Rats in model group, GH group and treatment group were injected intrauterine with 95%ethanol during estrus stage to construct a thin endometrial model. Six to eight hours after operation, rats in model group were injected intrauterine with 0.2 mL normal saline, rats in GH group and treatment group were injected with the same amount of GH, and the treatment group was given intragastric treatment of 60 mg/kg Vit.E. The rats were sacrificed 3 estrus cycles (about 2 weeks) after the operation. HE staining was performed on the uterine tissue to identify the model, and the levels of Cytokeratin 19 and Vimentin in the endometrium were detected by immunohistochemical color. RESULTS: The endometrial thickness of the model group was significantly thinner than that of the model group, and the endometrial thickness of the treatment group was significantly higher than that of the control group, but the endometrial thickness of the GH group was slightly lower than that of the control group. The expression levels of keratin and vimentin in model group were lower than those in GH group, control group and treatment group, and the differences were statistically significant. CONCLUSION: Endometrial-related proliferation indexes were significantly increased after GH and vitamin E treatment, and GH and vitamin E could effectively promote the proliferation of endometrial cells.