Determination of the composition of organic layers chemically bonded on silicon dioxide

Abstract

The dynamic response of the precipitate-based Ion-selective electrodes has been studied In detail In the so-called two-lon range. The effect of various parameters, e.g., flow rate, temperature, concentration of the Interfering Ion, and the electrode membrane surface condition on the transient signal was Investigated. A new model has been derived for the Interpretation of the processes resulting In the transient signal.

Binary Monolayer Mixtures: Modification of Nanopores in Silicon-Supported Tris(trimethylsiloxy)silyl Monolayers

“…The most widely used approach involves the treatment of a surface with a mixture of reagents (competitive chemisorption). By use of mixtures of organosilanes, binary monolayers of aryl (phenyl, , naphthyl, pyrenyl)/alkyl, alkyl/alkyl, ,− fluoroalkyl/alkyl, − ester/alkyl, haloalkyl/alkyl, ,− phthalimidoalkyl/alkyl, diphenylphosphino/alkyl, cyanoalkyl/alkyl, , and amino acid (valine)/alkyl groups were prepared. Preparation of mixed monolayers, in which one of the components is physically adsorbed, was described for alkyltrichlorosilanes with fatty acids , and alkyltrichlorosilanes with dyes .…”

Quantitative analysis of apolar polysiloxane phases in large-bore capillary columns

“…Strong fluorinating reagents furnish alkylfluorosilanes more quantitatively, and BF3 dissolved in ether [8,9] NaHF2 [10], or anhydrous HF [11] have been used for silicon analysis. The same reagents have also been used for analysis of monomeric alkyl graftings on the surface of silica used in RPHPLC [12], although the analysis can be performed more simply by use of 40 % hydrofluoric acid [13]. We have performed many assays to extend this technique to polymeric films; these experiments have included the use of the HF-pyridine complex (OLAH reagent) [14].…”

Chemical characterization of bonded stationary phases for high-performance liquid chromatography using hydrofluoric acid digestion and gas chromatography

“…The method was used to analyze a variety of commercial phases, showing widespread use of monofunctional silane chemistries and surprising bonding consistency among different manufacturers. Techniques for the characterization of bonded silane ligands on silica supports have included elemental analysis (1), basic hydrolysis (2-4), acid hydrolysis (5), pyrolysis GC (6), hydrofluoric acid/capillary GC (7), and most recently ESCA (8). Elemental analysis is the accepted method of choice for routine determination of carbon loading and bonded ligand density (1).…”

“…Erard et al (7) employed anhydrous hydrogen fluoride in diethyl ether for the selective cleavage of siloxane bonds on bonded silica gels. There is also extensive literature on the analysis of silicone polymers using Lewis acids such as boron trifluoride, aluminum trifluoride, or aqueous hydrofluoric acid (14-19).…”

“…The solute and associated matrix components can be preferentially solubilized into or onto the micellar assembly, a process which is dynamic and characterized by various rate constants (5,6). Micellar solutions have found use in generating room-temperature phosphorescence (RTP) (7) and sensitized room-temperature phosphorescence (SRTP) (8), in drug adsorption studies (9), and in chromatographic separations (10)(11)(12)(13)(14). The use of SDS as the mobile phase offers distinct advantages over conventional HPLC for therapeutic drug monitoring.…”