Support coated open tubular SCOT column

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

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. 

Figure 5. Gas chromatogram of methyl esters from the aqueous Na2Cr20y oxidation of Illinois No. 2 bituminous coal (separated on an OV-17 support coated open tubular column (SCOT), temperature...

Support-coated open tubular column (SCOT)... 

Open tubular or capillary columns have open unrestricted path for the gas within the column. These columns are about 15-30 meters in length with an inside diameter of about 0.25 mm. The inner wall of these columns is coated with the liquid stationary phase to about 1 m in thickness. The open tubular columns are of two kinds. One is known as the wall coated open tubular column [WCOT) in which the liquid phase is coated on the column wall. These columns have limited sample capacity and are unsuitable for large-scale separations. The second type is known as support coated open tubular columns (SCOT). In these columns a porous layer is formed on the inside wall of the tubing. The porous layer can either be formed by chemical treatment of the inner wall or is deposited on the inner wall. The support is coated in such a way that the inherent property of the capillary columns, i.e., the unrestricted gas flow is retained. The inert porous layer is then impregnated with the liquid stationary phase. These columns have a higher sample capacity. 

Column Material. If a capillary column is to be used, fused silica is the material of choice. A number of fused-silica capillary columns are available. The wall-coated open-tubular column (WCOT), where the liquid stationary phase is coated on the deactivated inside wall of the capillary, has become the most widely used type of capillary column. A second type of capillary column is the porous-layer open-tubular column (PLOT), in which the stationary phase consists of solid particles coated on the deactivated inside wall of the capillary. A third type of capillary column is the support-coated open-tubular column (SCOT), in which the liquid stationary phase is coated over the solid particles coated on the deactivated inside wall of the capillary. 

SCOT. Support Coated Open Tubular column. 

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). 

Open tubular, or capillary, columns are of two basic typos wall-coated open tubular (W( OT) and support-coated open tubular (SCOT) columns. Wall-coated columns are simply capillary tubes coated with a thin layer of the stationary phase. In support-coated open tubular columns, the inner surface of the capillary is lined with a thin film (—.30 pm) of a support material, such as diatomaceous earth. This type of column holds several times as much stationary phase as docs a wall-coated column and thus has a greater sample capacity. Generally, the efficiency of a SCOT column is less than that of a WCOT column but significantly greater than that of a packed column. 

SCOT = support-coated open tubular column. These columns are less popular today since thicker WCOT phases are now available. PLOT = porous layer open tubular column. 

The other types of capillary columns are shown in Figure 6.3, the SCOT or support-coated open tubular column, on the left, and the PLOT or porous layer open tubular column, on the right. SCOT columns contain an adsorbed layer of very small solid support (such as Celite ) coated with a liquid phase. SCOT columns can hold more liquid phase, and have a higher sample capacity than the thin films common to the early WCOT columns. However, with the introduction of cross-linking techniques, stable thick films are possible for WCOT columns, and the need for SCOT columns has disappeared. A few SCOT columns are still commercially available but only in stainless steel tubing. 

Some of these solids have been coated on the inside walls of capillary colunms and are called support coated open tubular or SCOT columns. More information about them is included in Chapter 6. 

SCOT. An acronym for support-coated open tubular column. These are capillary columns in which the liquid substrate is on a solid support that coats the walls of the capillary column. 

WWSCOT. An acronym for whisker-wall-support-coated open tubular column. It is a SCOT column in which the walls have been etched before depositing of the support. 

Support-coated open-tubular column, a capillary column in which stationary phase is coated onto a support material that is distributed over the column inner wall. A SCOT column generally has a higher peak capacity than a WCOT column with the same average film thickness. 

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

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... 

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... 

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... 

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... 

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 -... 

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. 

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