Capillary, coatings column

Capillary Tubes Figure 12.42 shows a cross section of a typical capillary tube. Most capillary tubes are made from fused silica coated with a 20-35-)J,m layer of poly-imide to give it mechanical strength. The inner diameter is typically 25-75 )J,m, which is smaller than that for a capillary GC column, with an outer diameter of 200-375 )J,m. 

The development of new fiber coatings in the near future should further improve the specificity of SPME and overcome some of the observed matrix effects. Quantification by stable isotope dilution gas chromatography/mass spectrometry (GC/MS) may assist in improving analytical performance. Along with the possible application of micro LC and capillary LC columns to in-tube SPME, the development of novel derivatization methods and the potential for the analysis of fumigant pesticides, SPME appears to be a technique with a future in the analysis of pesticide residues in food. 

Fused-silica capillary GC column, 15 m x 0.32-mmi.d., coated with trifluoropropyl-methyl polysiloxane (0.5- um film thickness)... 

Fused silica capillary GC column 30m x 0.25-mm i.d. coated with 5% phenyl (equiv.) polysilphenylene-siloxane (0.25-p.m film thickness)... 

Analysis Techniques. The contents of the major breakdown products of xetralin (naphthalene and 1-methyl indan) present in the distillate were determined by gas-liquid chromatography using a Hewlett Packard Series 5750 Research Chromatograph with a 62m x 0.5mm diameter glass capillary SCOT column coated with nonpolar SE 30 liquid phase (see Reference (4 ) for details). 

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. 

Lin, C.-C., and Liu, C.-Y. (2004). Proline-coated column for the capillary electrochromatographic separation of amino acids by in-column derlvatlzatlon. Electrophoresis 25, 3216-3223. 

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...

Chromatographic Resolution. To optimize column-coating conditions and operating parameters glass capillary columns coated with various silicone-based stationary phases were tested with difficult-to-separate groups of PAH standards and Complex samples. The SE5 -coated columns performed excellently with respect to separation efficiency, column bleed and long-term stability. Other observers have had similar results with this... 

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). 

A gas chromatograph of the Hewlett-Packard 5890 series with a HP 7673A injector and a flame ionisation detector can be used. A capillary free fatty acid phase (Hewlett-Packard FFAP 19091F-105) column (50 m x 0.20 mm x 0.33 pm) is cut into two equal 25-m lengths, which are used for the separation, provided that a capillary pre-column (J W Scientific Altech 93493) with a 50% phenyl silicone DB 17 coating (1.35 m of a 15 mx0.25 mmx0.25 pm column) is installed. 

GC column A capillary column of intermediate polarity can give adequate resolution of isomers as well as unsaturated compounds. Many such columns are commercially available. These include 105 m long x 0.53 mm ID, Rtx-502.2 60 m long x 0.75 mm ID, VOCOL 60 m long x 0.53 mm ID, DB-62 or equivalent. Other capillary columns include 95% dimethyl-5% diphenyl polysiloxane coated columns, such as DB-5, SPB-5, Rtx-5, AT-5, or equivalent. These columns are also suitable for separation of a number of nonhalogenated organic compounds of intermediate polarity. 

Figure 8. Enantiomeric purity of the isolated invertomers. Left racemic sample middle pure (R)-enantiomer right (SJ-enantiomer contaminated with (R)-enantiomer from incomplete preparative fractionation (ee = 98 %). Analytical column 25 m x 0.25 mm glass capillary coated with 0.125 molal nickel(II) bis[(2-heptafluorobutanoyl)-(TS,5S/)-4-methylthujonate] (Ni METHU2) in OV-101 at 50°C. The (R)-enantiomer is eluted before the (S)-enantiomer on (IS,5S)-Ni-METHU2 (Schurig and Leyrer, 1990).

A rapid method of analysis of organo-tin compounds in sediment and biological CRMs was developed (Pereiro et al., 1997). Ethylated butyltin compounds were separated isothermally on a multicapillary (MC) gas chromatographic column in less than 30 s as compared with 5-10 min on a regular capillary column. The MC column consisted of a bundle of about 900 1 m-long, 40 mm i.d. coated capillaries. The column was connected to a microwave-induced plasma atomic emission spectrometer. Phenyltin compounds were also included in the procedure. Detection limits of MBT, DBT and TBT were about 0.2ngml 1 (as tin). 

The stationary phase can be a liquid or a solid. If it is a liquid, it can be coated directly on the inside walls of a capillary tube (column), or it can be coated on an inert solid support and be handled like a solid. In effect, then, there are three stationary phase configurations in the first type, a solid (with or without stationary liquid) is packed into a column in the second type, a solid is coated on the surface of a flat, plane material like glass (TLC), and in the third type, a liquid is coated on the inside wall of an open tube (OT). 

Solid-phase microextraction (SPME) — is a procedure originally developed for sample preconcentration in gas chromatography (GC). In this procedure a small-diameter fused silica optical fiber, coated with a liquid polymer phase such as poly(dimethylsiloxane), is immersed in an aqueous sample solution. The -> analytes partition into the polymer phase and are then thermally desorbed in the GC injector on the column. The same polymer coating is used as a stationary phase of capillary GC columns. The extraction is a non-exhaustive liquid-liquid extraction with the convenience that the organic phase is attached to the fiber. This fiber is contained in a syringe, which protects it and simplifies introduction of the fiber into a GC injector. Both uncoated and coated fibers with films of different GC stationary phases can be used. SPME can be successfully applied to the analysis of volatile chlorinated organic compounds, such as chlorinated organic solvents and substituted benzenes as well as nonvolatile chlorinated biphenyls. 

The capillary column used was a 50 mX 0,32 mm (i.d.) fused silica UCON 75H 90000 wall coated column. The column oven temperature was programmed from 30 to 180°C at a rate of 3"C/min with a 10-min post injection hold and a 10-min hold at a final limit. Column inlet pressure of Helium was 7 psl and the split 30 mL/min. 

Proteins like insulin, myoglobin and lysozyme were also loaded onto the non-coated CE capillary and collected for nES/MS analysis and Edman sequencing. Because the peak width of proteins is larger than that of the peptides on the non-coated column, the window is relatively wide (about 10 minutes) under 7.5 kV for fraction collection. Figure 8a is the nES/MS spectrum of... 

In pioneering work by Ptereira et al., the derivatization of racemic alcohols with (+)-[19] was carried out to produce diastereomeric carbamates that could be resolved on stainless steel capillary GLC columns coated with Carbowax 20M or OV-225 stationary phase (166). The retention times, however, ranged between 28 and 90 min, rendering the technique somewhat inconvenient. Gal et al. used capillary GLC columns to separate... 

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