Deactivation with Silazanes in Chromatography, Mechanism of the Reaction and Practical Consequences in Capillary GC and RP-HPLC: A2’Si CP-MAS NMR Study
نویسندگان
چکیده
predominates only below ca. 400“C.Above ca. 400°C the intermediate cleavage product Me,SiNH, reacts with surface silanot groups to form iSiOSiMe,NH, + CH,. At higher temperatures these groups may ultimately form (3iO),SiNH, groups (analogously to the formation of bi-and tridentate linkages starting from :SiOSiMe, groups), but (3SiO),SiNH, groups are also directly formed at lower temperatures, simultaneously with the iSiOSiMe3 groups, probably by reaction with siloxane bridges:
منابع مشابه
Determination of chemical and radiochemical purity of [14C] clozapine by high performance liquid chromatography and liquid scintillation [Persian]
Introduction: The mechanism of action and metabolism of clozapine, a complex drug used in psychopharmacology, is not completely understood. The effects of this compound in human body are related to some interactions with serotonin and dopamine neurotransmitter receptors. To further elucidate the mechanism of action and to support ongoing drug metabolism studies, [14C] clozapine with suita...
متن کاملSurface Characterization of Some Novel Bonded Phase Packing Materials for HPLC Columns Using MAS-NMR Spectroscopy
Information on the surface properties of three novel chemically bonded phase packing materials for High performance liquid chromatography (HPLC) were obtained using spectra obtained by solid state cross-polarization (CP) magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopic experiments for the 29Si, and 13C nuclei. These packing materials were: Cogent bidentate C18 bonded to...
متن کاملEFFECTS OF TEMPERATURE AND PERCENTAGE OF ORGANIC MODIFIER ON RETENTION AND SELECTIVITY IN RP-HPLC USING SOLVATION PARAMETER MODEL
Effects of temperature and percentage of organic modifier were studied on retention and selectivity in RP-HPLC using solvation parameter model. The system constants were determined by multiple linear regression analysis from experimental values in the retention factor for a group of different solutes with known descriptors by computer using the program SPSS/PC. The experimental results showed t...
متن کاملInvestigation of Behavior of Forced Degradation of Lidocaine HCl by NMR Spectroscopy and GC-FID Methods: Validation of GC-FID Method for Determination of Related Substance in Pharmaceutical Formulations
The forced degradation study of lidocaine HCl was carried out according to the ICH guideline Q1A (R2). The degradation conditions were assessed to be hydrolysis, oxidation, photolysis and dry heat during 24 h, 48 h and 72 h and then the samples were investigated by GC-FID method and nuclear magnetic resonance (NMR) spectroscopy. According to these results, the degradation products were not o...
متن کاملPerformance of 2-Amino Tetraphenyl Porphyrin as Stationary Phase in RP-HPLC of Amino Acids
The search for new stationary phases has been one of the predominant concerns in high performance liquid chromatography (HPLC) in order to achieve better resolutions, longer column lives, and reduce the time of analysis. A chromatographic packing for separation of underivatized amino acids (AAs) were prepared by dynamically coating 2-amino tetraphenyl prophyrin (atpp) on a C-18 reversed-pha...
متن کامل