High-performance liquid chromatography of benzodiazepines using sorbents with thermally immobilized Carbowax 20M

Porous Silica Matrix Obtained from Pyrex Glass by Hydrothermal Treatment: Characterization and Nature of the Porosity

“…29 Si MASNMR spectrum of the thermally treated sample ( Fig. 6(b)) presents peaks at Ϫ103 and Ϫ110 ppm assigned to silicon atoms with the structural units (SiO) 3 SiOAl tetra and (SiO) 4 Si, respectively. The silicon peak at Ϫ110 ppm exhibits a relative decrease in line width, ϳ200 Hz, indicating that thermal treatment improves the environmental organization which promotes specific crystallographic sites for silicon atoms.…”

“…7 led to a strong and selective enhancement of the NMR signal, with a characteristic dependence of the relative intensities on the chosen t c values for cross polarization. 26 The peak at Ϫ102 ppm was attributed to an (SiO) 3 SiOH surface group because the Si-H distance is the shortest, and the peak at Ϫ110 ppm was attributed to the (SiO) 4 Si groups. These results indicate that the porous matrix can be used for exchange reactions.…”

“…1 The porous materials are divided into three categories: 2 micro (Ͻ20 Å), meso (20 -500 Å), and macro (Ͼ500 Å). These materials exhibit numerous properties, including low density, high-temperature stability, high surface area, and thermal shock resistance, and, thus, can be used as supports for chemically bonded or adhesively deposited phases, 3 catalysts or supports for substances possessing catalytic properties, 4 and supports for enzymes or microorganisms used in biocatalytic transformations. 5 Some applications of porous materials-for example, as filters and electrodes for fuel cells-are important when ecological issues and energy savings are concerned.…”

Photocatalytic TiO2/Glass Nanoflake Array Films

“…These materials show attractive properties, including low density, high-temperature stability, and thermal shock resistance. They are, therefore, widely used as supports for substances possessing chemical or biological catalytic properties . Ceramics are often prepared with a surface layer that imparts a specific functionality or acts as a protective layer for the bulk materials 9a.…”