Influence of silica gel pretreatment and bonding technique on PAH selectivity of octadecyl bonded phases

1987 ◽  
Vol 24 (1) ◽  
pp. 324-328 ◽  
Author(s):  
P. J. van den Driest ◽  
H. J. Ritchie
Keyword(s):  
Silica Gel ◽  
Bonded Phases ◽  
Bonding Technique

Silica Gel and Bonded Phases

1994 ◽  
Vol 285 (3) ◽  
pp. 401
Author(s):  
K.K. Unger
Keyword(s):  
Silica Gel ◽  
Bonded Phases

A bonded polyoxyethylene phase for gas and liquid chromatography

1986 ◽  
Vol 64 (3) ◽  
pp. 470-476 ◽  
Author(s):  
Palitha P. Wickramanayake ◽  
Walter A. Aue
Keyword(s):  
Liquid Chromatography ◽  
Silica Gel ◽  
High Efficiency ◽  
Gel Permeation Chromatography ◽  
Plate Height ◽  
Bonded Phases ◽  
Elution Pattern ◽  
Gas And Liquid Chromatography ◽  
Unmodified Silica ◽  
New Phase

Bonded phases were produced by reacting 2,4,7,9-tetramethyl-5-decyne-4,7-bis(polyethyleneoxide 30 mol) ether (Surf[Formula: see text]nol® 485) with silicic supports of high and low surface area. There is circumstantial evidence (a) that the nonextractable layer is held by multiple hydrogen bonding and (b) that the synthesis of these packings involves a reaction at the crosslinking site of the surfactant. The bonded phases, with layer thicknesses between 10 and 30 Å, were tested with three chromatographic techniques. In gas–solid chromatography, the phase proved well deactivated and yielded a reduced plate height of 2.5 (using a silica gel support). In gel permeation chromatography, polyethyleneglycols eluted within the mobile-phase volume. In liquid–solid (normal-phase adsorption) chromatography, the elution pattern differed significantly from that of unmodified silica gel. In each case, high-efficiency separations were obtained. The chromatographic experiments thus demonstrated the potential usefulness of the new phase for both gas and liquid chromatography. However, it was not tested in direct comparison with conventional phases nor was its utility established by subjecting it to routine analytical use.

Structural relationships in the synthesis of cubic boron nitride thin films by ion-assisted deposition

1994 ◽  
Vol 52 ◽  
pp. 638-639
Author(s):  
D. L. Medlin ◽  
T. A. Friedmann ◽  
P. B. Mirkarimi ◽  
M. J. Mills ◽  
K. F. McCarty
Keyword(s):  
Boron Nitride ◽  
Ion Irradiation ◽  
Cubic Boron Nitride ◽  
Film Stress ◽  
Bonded Phases ◽  
Structural Relationships ◽  
Precursor Material ◽  
Pressure Synthesis ◽  
Microstructure Of The Material

The allotropes of boron nitride include two sp2-bonded phases with hexagonal and rhombohedral structures (hBN and rBN) and two sp3-bonded phases with cubic (zincblende) and hexagonal (wurtzitic) structures (cBN and wBN) (Fig. 1). Although cBN is synthesized in bulk form by conversion of hBN at high temperatures and pressures, low-pressure synthesis of cBN as a thin film is more difficult and succeeds only when the growing film is simultaneously irradiated with a high flux of ions. Only sp2-bonded material, which generally has a disordered, turbostratic microstructure (tBN), will form in the absence of ion-irradiation. The mechanistic role of the irradiation is not well understood, but recent work suggests that ion-induced compressive film stress may induce the transformation to cBN.Typically, BN films are deposited at temperatures less than 1000°C, a regime for which the structure of the sp2-bonded precursor material dictates the phase and microstructure of the material that forms from conventional (bulk) high pressure treatment.

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