Capillary coatings

The gas chromatographic separation of some sulphoxide enantiomers was observed on quartz fused silica capillaries coated with the chiral silicon phase chirasil-val280. 

Capillaries coated with MIP have also been used successfully for chiral separation [34]. Schweitz et al. also synthesized highly porous, monolithic Ml-poly-mers inside such capillaries for the separation of S- and R-propranolol [38,90]. Figure 8 A shows a baseline separation of S-propranolol from the R-enantiomer in such capillaries, the latter of which was used as template. The difference in retention times for the two enantiomers was verified by analyzing the two chiral compounds also individually see Fig. 8B, C. 

Figure 6. GC separation of the enantiomers of all protein amino acids on a capillary coated with...

Flame ionisation. Flame Photometric and Thermionic Detection use a Perkin—Elmer Sigma 1 gas chromatograph, equipped with an S.G.E on-column injector. The column used was a 25 metrex0.31mm I.D. fused silica WCOT capillary coated with BP-1 (S.G.E), a methyl silicone. 

The further development of chemicals and capillaries, coatings and consumables, and ready-to-use generic methods... 

Strong acids-. Acids such as H3PO4 or HCl also give harsher treatment than BGE or water, but without deprotonation of the silanol groups of the wall. An acid wash is not compatible with all capillary coatings. 

Capillary coating can also stabilize the migration times and resolutions. This is in particular necessary in the case of peptide and protein analysis, because proteins tend to stick to capillary walls. Often low-concentration polyethylene oxide solutions are recommended as well as dynamic bilayer coating formed by a non-covalent adsorption of polybrene and polyvinylsulfonate (PVS). Due to the stability of the EOF, the variation of intra- and intercapillary migration time was less than 1% relative standard deviation (RSD) with basic analytes and peptides. 

A wide choice of cationic surfactants such as CTAB (cetyltrimethylammonium bromide), CTAH (cetyltrimethylammonium hydroxide), TTAB (tetradecyltrimethylammonium bromide), TTAOH (tetradecyltrimethylammonium hydroxide), MTAB (myristyltrimethylammo-nium bromide), OFM (OFM Anion-BT, Waters, Milford, MA, USA), HDB (hexadimethrine bromide), and many others may be used to reverse the EOF. CTAH and TTAOH should be preferred to CTAB and TTAB to avoid interference from bromate contamination. The capillary coating is performed just by rinsing with the BGE containing this flow modifier or even with an additional rinse step with a solution containing this flow modifier. 

The buffer used was CEofix Anions 5 (Analis Suarlee, Belgium), consisting of a PDC acid at pH 5.6 and a poly cation for capillary coating. The method was based on the standatd... 

Mayer, S., and Schurig, V. (1992). Enantiomer separation by electrochromatography on capillaries coated with Chirasil-Dex./. EUgh Resolut. Chromatogr. 15, 129 — 131. 

H Katayama, Y Ishihama, N Asakawa. Development of novel capillary coating based on physical adsorption for capillary electrophoresis. Anal. Sci. 14 407-408 (1998). 

CZE-ELD, with a Au microelectrode at —0.6 V vs. SSCE and a Pt wire as auxiliary electrode, using sodium borate buffer and dodecyltrimethylanunonium bromide for dynamic coating of the capillary internal surface, can be applied for separation and determination of ultra-trace amounts of many oxidizing substances. Thus, the concentration of peroxodisulfate (S208 ) and peroxomonosulfate (S05 ) ions in pickling baths can be monitored by this method. The faster emergence of the heavier peroxodisulfate ion is attributed to different adsorption of the two analyte ions by the capillary coating . ... 

Fused silica capillary coated with polyamide... 

Several different analytical and ultra-micropreparative CEC approaches have been described for such peptide separations. For example, open tubular (OT-CEC) methods have been used 290-294 with etched fused silicas to increase the surface area with diols or octadecyl chains then bonded to the surface.1 With such OT-CEC systems, the peptide-ligand interactions of, for example, angiotensin I-III increased with increasing hydrophobicity of the bonded phase on the capillary wall. Porous layer open tubular (PLOT) capillaries coated with anionic polymers 295 or poly(aspartic acid) 296 have also been employed 297 to separate basic peptides on the inner wall of fused silica capillaries of 20 pm i.d. When the same eluent conditions were employed, superior performance was observed for these PLOT capillaries compared to the corresponding capillary zone electrophoresis (HP-CZE) separation. Peptide mixtures can be analyzed 298-300 with OT-CEC systems based on octyl-bonded fused silica capillaries that have been coated with (3-aminopropyl)trimethoxysilane (APS), as well as with pressurized CEC (pCEC) packed with particles of similar surface chemistry, to decrease the electrostatic interactions between the solute and the surface, coupled to a mass spectrometer (MS). In the pressurized flow version of electrochromatography, a pLC pump is also employed (Figure 26) to facilitate liquid flow, reduce bubble formation, and to fine-tune the selectivity of the separation of the peptide mixture. 

Figure 2. Capillary-column gas chromatogram of the total polynuclear hydrocarbon fraction of air-particulate matter ). Conditions 11 m X 0.26 mm -i.d. glass capillary coated with SE-52 methylphenylsilicone stationary phase see Table 1 for...

Figure 6.8 Preparation of a capillary coated with zwitterionic salt.

Analytical Methods. The samples of PAH were extracted with cyclohexane, and the extract was subjected to liquid-liquid extractions with N,N-dimethylformamide as reported elsewhere (26). Following a concentration step, the extract was analyzed by GCZ using a Carlo Erba Fractovap 2101 equipped with a flame ionization detector. The column was a 50 m x 0.32 mm i.d. persilanized glass capillary coated with 0V-73 according to the Grob method (27). 

Supelcoport with 3% OV-7 or HP-5, 25 m, capillary coated with 5% phenyl methyl silicone... 

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