Silanisation

Dibenzyl-14-crown-4 (lithium ionophore VI 6,6-dibenzyl-l,4,8,ll-tetra-oxa-cyclo-tetradecane) [106868-21-7] M 384.5, m 102-103°. Dissolve in CHCI3, wash with saturated aqueous NaCl, dry with MgSOa, evaporate and purify by chromatography on silica gel and gradient elution with C6Hg-MeOH followed by preparative reverse phase HPLC on an octadecyl silanised silica (ODS) column and eluting with MeOH. It can be crystd from MeOH (v Br 120 cm , C-O-C). [7 Chem Soc Perkin Trans 1 1945 1986.]... 

In a second experiment, Cy5-labelled antiBSA antibodies were immobilised on a silanised glass slide precoated with metallic nanoislands using a polydimethylsiloxane (PDMS) flow-cell. The antibody solution was left for 1 hour to attach and then the cell was flushed with deionised water. The slide was then dried with N2. For this experiment, a portion of the slide was not coated with metallic nanoislands, in order to act as a reference. Figure 20 shows the image recorded using the fluorescence laser scanner mentioned previously. The enhancement in fluorescence emission between those areas with and without nanoislands (B and A, respectively) is again evident. For both chips, an enhancement factor of approximately 8 was recorded. There is considerable interest in the elucidation and exploitation of plasmonic effects for fluorescence-based biosensors and other applications. 

A disadvantage of the reversed-phase HPLC technique or that of Derenbach et al. [82] is that it is only semi-quantitative. Against this is the fact that the technique using silanised porous glass is easy to keep free of contamination, has a comparatively high adsorption capacity, and permits the fractionated desorption of accumulated material. 

In the adsorption with Tenax alone satisfactory results were obtained, while in the presence of mineral oil a considerable proportion of the organophos-phorus pesticides (particularly Malathion and Parathion-methyl) was not adsorbed and was recovered in the filtered water. This drawback can be overcome by adding a layer of Celite 545 which, in order to prevent blocking of the column, is mixed with silanised glass wool plugs. A number of analyses of surface and estuarine sea waters were carried out by this modified Tenax column and simultaneously by the liquid-liquid extraction technique. To some of the samples taken, standard mixtures of pesticides were also added, each at the level of 1 xg/l (i.e., in concentration from 13 to 500 times higher than that usually found in the waters analysed). One recovery trial also specifically concerned polychlorobiphenyls. The results obtained in these tests show that the two extraction methods, when applied to surface waters that were not filtered before extraction, yielded very similar results for many insecticides, with the exception of compounds of the DDT series, for which discordant results were frequently obtained. 

The surface-active properties of surfactants could give rise to sorption of analytes to glassware and equipment. However, the literature shows that when a comparison is made between the use of silanised glassware and careful rinsing of normal glassware with methanol during sample treatment, the latter (cheaper) solution is sufficient [5]. 

Ethyloestrenol Glass column (1.0 M x 4 mm) packed with acid-washed silanised diatomaceous support (80 to 100 mesh) coated with 3% w/w of phenyl methyl silicone fluid (50% phenyl) maintained at 200 °C. OV-17 is also suitable. (1) 0.2 w/v of ethyloestrenol BPCRS and 0.1% w/v of arachidic alcohol (internal standard) (2) 0.2% w/v of sample (3) 0.2% of sample plus 0.1% w/v of Ihe internal standard. Calculate the content of C20H32O using the declared content of C20H32O ethyloestrenol BPCRS. 

K. Jones, Optimisation procedure for the silanisation of silicas for reversed-phase high-performance liquid chromatography. I. Elimination of nonsignificant variables, J. Chromatogr., 392 (1987) 1-10. 

In order to deposit a film of known thickness, a silanised column is filled with a solution of known concentration of stationary phase (e.g. 0.2% in ether) so that the desired thickness is obtained after evaporation. This layer can then be reticulated by peroxide or gamma radiation. The process is similar to the fixation of a dye on a... 

Silicone GE SE-30 350 A High temperature general use when on silanised... 

A commercially packed h.p.l.c. column (25 cm x 4.6 mm) of y-aminopropyl silanised silica [e.g. 5/mi Spherisorb (Regis Chemical Co.), or 7/im Zorbax (Dupont Co.), or 10 /im Lithosorb (Merck), or 5 m irregular (J. T. Baker Chemical Co.)] was sequentially treated, at a pumping rate of 2 ml/min, with the following solutions 2 ml of triethylamine in 40 ml of dry tetrahydrofuran, 2g of (R)-JV-(3,5-dinitrobenzoyl)phenylglycine in 40 ml of dry tetrahydrofuran, 20 ml of dry tetrahydrofuran, and finally 10 per cent propan-2-ol in hexane, until the base line stabilises. The chiral amino acid derivative (which is available from Aldrich Chemical Co.) becomes ionically bonded to the amino residues on the stationary phase. 

Beezhold and Stout [68] studied the effect of using mixed standards on the determination of PCBs. Mixtures of Arochlors 1254 and 1260 were used as comparison standards and gas chromatograms of these mixtures were compared with those obtained from a hexane extract of the sample after clean-up on a Florasil column. Polychlorinated biphenyls were separated from DDT and its analogues on a silica gel column activated for 17h and with 2% (w/w) of water added. The extracts were analysed on a silanised glass column packed with 5% DC-200 and 7.5% QF-1 on Gas Chrom Q (80-100 mesh) operated at 195°C with nitrogen as carrier gas (50-60mL min-1) and a tritium detector. 

The sample extracts were ran with an electron capture detector (63Ni). The 2.4mx0.18cm (id) glass column was filled with a mechanical mixture of two parts of 8% QF-1 and one part of 4% SF-96 on acid-washed silanised Chromosorb W (100-120 mesh). Typical chromatograms obtained by this procedure are shown in Fig. 15.7. 

Petroleum hydrocarbons SE-52 on silanised Chromosorb W, 50-300°C Flame ionisation also infrared spectroscopy [627]... 

Enhancement of a flexible PVC-silica composite interface was studied by the application of gamma-aminopropyltrimethoxysilane on silane. Composites containing silica and silanised silica up to 25.6 phr and prepared by sol-gel technology were subjected to water and water vapour attacks similar to that in their daily use. Silane application resulted in diminishing liquid water and water vapour sorption by about 24.0% and 11.9%, respectively. Inhibition of dioctyl phthalate migration from composites by silane application was also determined as 24% using UV measurements. 20 refs. TURKEY... 

Disposable containers should be used whenever possible to reduce die possibility of contamination. Liquid samples (blood, urine, and bile) are best placed in glass containers which e sealed widi a liner that is impervious to the sample (e.g. a FIFE liner). Liners made of rubber and similar materials should be avoided since they may absorb drugs or condibute contaminants (e.g. plasticisers) to die s ple. Glass may need to be silanised when low concentrations (< 10 ng/ml) of drugs are present to avoid adsorption onto the walls. 

Various deactivation procedures are applied to support materials. These include acid- or basewashing to remove impurities and fine particles, and treatment with a silanising agent which reacts with surface hydroxyl groups and reduces adsorptive effects. A very light coating of a polar stationary phase may also be used to increase deactivation. Commercial support materials which have been treated by these procedures are available and are usually designated by a suffix to the name, e.g. AW (acid washed) and AW HMDS (acid washed, hexamethyldisilazane treated). Deactivated supports are nearly always to be preferred, but it should be noted that the deactivation procedure may impose an upper temperature limit and may modify the polarity of the stationary phase. 

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