Support-coated open tubular

Porous-layer- open tubular (PLOT) and support-coated open tubular (SCOT) columns are prepared by extending the inner surface area of the capillary tube. A layer of particles can be deposited on the surface or the column wall can be chemically treated to create a porous adsorbent layer. Obviously some of the wall-modified open tubular columns discussed in section 2.3.3 could be... 

QITMS Quadrupole ion trap mass SCOT Support-coated open-tubular... 

The gas chromatographic determination of isomers of dinitrotoluene in seawater has been described by Flashimoto and co-workers [296,297]. These authors describe the complete separation of six dinitrotoluene isomers using gas chromatography with support-coated open tubular glass capillary columns and electron-capture detection. The method was applied to the qualitative and quantitative analyses of trace levels of isomers in seawater and the results were found to be satisfactory, with no need for further clean-up procedures. 

Support coated open tubular (SCOT) columns, 4 615 6 379 Supported liquid membranes, 16 28 Support material, in fluidized-bed encapsulation, 11 540 affinity chromatography, 6 392-393 chromatography, 6 375 gas chromatography, 6 375 Supported metals... 

Support-coated open tubular column (SCOT) liquid stationary phase coated on solid support attached to inside wall of column... 

SCOT. Support Coated Open Tubular column. 

FLOW. The rate at which zones migrate down the column is dependent upon equilibrium conditions and mobile phase velocity on the other hand, how the zone broadens depends upon flow conditions in the column, longitudinal diffusion, and the rate of mass transfer. Since there are various types of columns used in gas chromatography, namely, open tubular columns, support coated open tubular columns, packed capillary columns, and analytical packed columns, we should look at the conditions of flow in a gas chromatographic column. Our discussion of flow will be restricted to Newtonian fluids, that is, those in which the viscosity remains constant at a given temperature. 

PLOT Columns. Porous-layer open tubular columns wherein the internal wall is coated with a layer of adsorbent support. If the support is then coated with a liquid phase it is referred to as a SCOT Column (i.e., support-coated open tubular column). 

Analyses. Hydrocarbon analyses for the gaseous products were made using a 1200 Varian gas chromatograph with a 30.5 m (100 ft) support coated open tubular squalene capillary and a 21-104 Consolidated Electrodynamics Corp. mass spectrometer. 

Cramers et al5 described high resolution gas chromatography for the quantitative determination of underivatized anti-convulsant drugs with support coated open tubular columns. 

One type of column is the wall-coated open tubular column (WCOT) in which the stationary phase is applied and bound directly to the walls of the column. Porous-layer open tubular columns (PLOT) are columns in which the stationary phase is deposited on fine particles of absorbent, absorbed on the walls of the column, increasing the available surface area of the column wall. Support-coated open tubular (SCOT) columns are those... 

B. Caddy, F. Fish, and D. Scott, Chromatographic screening for drugs of abuse using capillary columns, part 1, comparison of open tubular columns and support coated open tubular columns for the analysis of central nervous system stimulant drugs, Chro-matographia, 6 251 (1973). 

Fig. 7.1 shows the trace obtained from the analysis of undegraded linear alkylbenzene sulphonate (LAS) mixture (sodium dodecylbenzene sulphonate). Peak identifications were made by co-injection with pure undegraded linear alkylbenzene sulphonate compounds and confirmed by analysis of the undegraded linear alkylbenzene sulphonate mixture by desulphonation followed by gas chromatography of the resultant alkylbenzenes on a 15m OV-1 support coated open-tubular column. 

Suzuki et al. [819] studied the determination of chlorinated insecticides in river and surface waters using high resolution electron capture gas chromatography with glass capillary columns. They compared resolution efficiencies of organochlorine insecticides and their related compounds with wall-coated open tubular (WCOT) and support-coated open tubular (SCOT) glass capillary columns with those of conventional... 

The column which gives the most effective separation of the mixtures of accelerants generally encountered is a Support-Coated, Open Tubular (SCOT) column commercially available from Perkin-Elmer Corporation. The stainless steel column is 0.020 inch inner diameter coated with DC 550 on an inert support and consists of two fifty-foot sections joined with a zero dead... 

Figure 5 compares chromatograms of A8- and A9-THC-TMS and 11-hydroxy-A8-THC-TMS obtained on a glass capillary column and a 6ft. x 2mm I.D. packed column. The retention times of the cannabinoids are comparable, but the resolution and sensitivity achieved on the capillary column is far superior. The capacity of the capillary column is of course far less than that of the packed column. Nevertheless, by using a Grob-type splitless injector (7) we are able to inject several microliters of solution containing up to 50 ng of each cannabinoid without overloading the column. Use of a support-coated open tubular column should increase the column capacity, but at some sacrifice of resolution and sensitivity. 

For a period of time, OT columns that had characteristics intermediate between those of WCOT and packed columns were popular. There were two types, but they were similar. Support coated open tubular (SCOT) columns had a thin layer of solid support coated on the inside wall of a capillary tube of larger diameter than that used for WCOT columns. This layer was coated with stationary liquid similar to packed columns. Porous layer open tubular (PLOT) columns were similar but made differently for example, the solid support was added while the capillary tube was being drawn. With a few exceptions, SCOT and PLOT columns are no longer popular because wide diameter WCOT fused silica columns are as good, more stable (no layer to flake off), and easier to use. Subsequent discussion will be restricted to WCOT columns. 

It is usually necessary to modify the inside surface to assist wetting, e.g. by etching. If the glass surface itself is coated the column is referred to as a wall-coated open tubular (WCOT) column, whereas support-coated open tubular (SCOT) columns have a support bonded on to the glass walls, e.g. microcrystals of sodium or barium chloride. 

Gas chromatography and gas chromatography/mass spectrometry were employed to identify and quantitate individual molecular components. Both 25 and 50 meter glass support coated open tubular (SCOT) and fused silica wall coated open tubular (WCOT) capillary columns (SE.30, BP.l and BP.5 phases) were used with H2 as a carrier gas and F.I.D. detection. Acidic components were derivitized (BF3/methanol) to their methyl esters and hydroxyl groups to their silyl ethers (N,0-bis-(trimethylsilyl)trifluoroacetamide) in order to improve chromatographic separation. Carbon Preference Indices (CPI) were calculated using the equation -... 

SCOT support-coated open tubular (capillary column)... 

A range of open tubular GC columns were used. A 150 ft X 0.01 in. i.d. stainless steel wall-coated open tubular (WCOT) column (Perkin Elmer Corp., Norwalk, CT), a 50 ft X 0.02 in. i.d. support coated open tubular (SCOT) column (Perkin Elmer), and 33 ft and 100 ft X 0.03 in. i.d. porous layer open tubular (PLOT) columns. The latter were pre-... 

Several types of surface modification have been employed [37,38] such as etching or deposition of very fine inert supports before application of the phase. The latter are referred to as support coated open tubular (SCOT) or by others as porous layer open tubular (PLOT) columns. They have a higher sample capacity than liquid coated columns due to the greater amount of phase per unit length. Several recent papers have described modified methods of column preparation [39-41] using Silanox 101 as the support. 

Open tubular columns are simply capillary tubes in which the inside of the column wall is used as the support for the liquid phase. These wall-coated open tubular columns (WCOT) have the stationary phase distributed in the form of a thin film on the inside surface of the open capillary tube, the walls thus serving as the support. In order to reduce the thickness of the liquid phase film, a porous layer may be formed on the inside wall of the capillary tubing and then coated with the liquid phase to produce a support-coated open tubular column (SCOT). Porous-layer open tubular colunms (PLOT) are similar to SCOT colunms, the difference being that in the former, the stationary phase is deposited on fine crystalline particles or glass powder which is adsorbed onto the walls of the tube. In both cases, the available surface area of the wall is increased, and allows an increased amount of liquid phase to be accommodated in the same length and diameter of tubing. The whisker-walled (WW) colunm consists of whiskers chemically etched on the surface of the wall, which also result in a significant increase in the available surface area. Wall-coated, porous-layer, and support-coated capillary columns are all available as whisker-walled, i.e., WWCOT, WWPLOT, and WWSCOT, respectively. 

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