Open tubular columns solid

An open tubular column in which the stationary phase is coated on a solid support that is attached to the column s walls. 

Kovat s retention index (p. 575) liquid-solid adsorption chromatography (p. 590) longitudinal diffusion (p. 560) loop injector (p. 584) mass spectrum (p. 571) mass transfer (p. 561) micellar electrokinetic capillary chromatography (p. 606) micelle (p. 606) mobile phase (p. 546) normal-phase chromatography (p. 580) on-column injection (p. 568) open tubular column (p. 564) packed column (p. 564) peak capacity (p. 554)... 

Small solid seuaples can be analyzed directly by dynamic headspace sampling using a platinum coil and quartz crucible pyrolyzer and cold trap coupled to an open tubular column (341,369,379). This method has been used primarily for the analysis of mineral samples and of additives, catalysts and byproducts in finished polymers which yield unreliable results using conventional headspace techniques owing to the slow release of the volatiles to the headspace. At the higher temperatures (450-1000 C) available with the pyrolyzer the volatiles are more readily and completely removed from the sample providing for quantitative analysis. 

EPA. 1990a. Application of open-tubular columns to SW-846 GC methods. In Test methods for evaluating solid waste. SW-846. Washington, DC U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response. EPA/600/S4-90/021. 

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

A relatively nonvolatile liquid (at operating temperature) which is either sorbed on the solid support or coated on the walls of open tubular columns where it acts as a solvent of the sample. 

The material used as the carrier effects the time required to evaporate polar compounds whereas nonpolar compounds do not appear to have this problem. A quartz needle is the basis of an all glass solid-sampling device described for use with open tubular columns (24). 

Once the sample reaches the chromatographic column, the separation process starts. The time necessary for a component injected into the chromatographic column to elute is called the absoiute retention time tR. The separation is based on different retention times of the components of the mixture. These retention times are different because the partition of each analyte between the two phases, the gas phase in motion and the stationary phase, are different. Hydrogen, helium, and nitrogen are common gases used as mobile phase. Two basic types of columns are known packed columns containing solid support particles coated with the stationary phase, and open-tubular columns with the stationary phase as a film on the inner wall (capillary columns). Because the retention time tpfi) of the analyte i is temperature dependent, the chromatographic column of any (GC) is put in an oven with temperature control capability. 

Gas chromatography (GC) was first described by Martin and James in 1952. It has become one of the most frequently used separation techniques for the analysis of gases and volatile liquids and solids. An important breakthrough in GC was the introduction of the open tubular column by Golay in 1958 and the adoption of fused silica capillary columns by Dandeneau and Zerenner in 1979. 

The split/splitless detector has been designed for use with open-tubular columns or solid-coated open-tubular (SCOT) columns. Due to the small dimensions of such columns, they have very limited sample load capacity and, thus, for their effective use, require sample sizes that are practically impossible to inject directly. The split injector allows a relatively large sample (a sample size that is practical to inject with modern injection syringes) to be volatilized, and by means of a split-flow arrangement, a proportion of the sample is passed to the column while the remainder is passed to waste. A diagram of a split/splitless injector is shown in Fig. 1. 

Two types of columns are used in SFC packed columns containing solid particles of small inner diameter or wall-coated open-tubular columns (WCOT), usually called just capillary columns. Packed columns have been preferred when capacity is the most relevant issue capillary columns are selected when efficiency is the goal. 

The pioneering gas-liquid chromatographic studies in the early 1950s were carried out on packed columns in which the stationary phase was a thin film of liquid retained by adsorption on the surface of a finely divided, inert solid support. From theoretical studies made during this early period, it became apparent that unpacked columns having inside diameters of a few tenths of a millimeter could provide separations that were superior to those of packed columns in both speed and column efficiency. In such capillary columns, the stationary phase was a film of liquid a few tenths of a micrometer thick that uniformly coated the interior of capillary tubing. In the late 1950s, such open tubular columns were constructed the predicted... 

Gas-solid chromatography is performed with both packed and open tubular columns. For the latter, a thin layer of the adsorbent is affixed to the inner walls of the capillary. Such columns are sometimes called porous-layer open tubular columns, or PLOT columns. Figure 31-16 shows a typical application of a PLOT column. 

Porous layer open tubular (PLOT) solid stationary phase on inside wall of column. 

Koski, I. J., Lee, E. D., Ostrovsky, I., and Lee, M. L., Solid-phase injector for open tubular column supercritical fluid chromatography. Anal. Chem., 65, 1125-1129, 1993. 

PLOT Porous layer open tubular column used in capillary GC, consists of a thin layer (1-5 pm) of solid stationary phase material, e.g. modified alumina, coated onto the inner wall of silica capillary tubing see capillary GC. 

According to Scott the average linear velocity can be replaced by (4uq / [P -i- 1]) in Eq. (1.23) to permit evaluation entirely in terms of the outlet velocity [130]. If X = 0, y = 1, and dp = rc is substituted into Eq. (1.23) then this equation can be used as an alternative to Eq. (1.22) to account for band broadening in evaluating open tubular columns [121,130]. For gas-solid chromatography the stationary phase mass transfer... 

Wall-coated open tubular columns (WCOT columns), or simply capillary columns, and classical packed columns dominate the practice of gas-liquid chromatography today. Porous layer open tubular columns (PLOT columns) and classical packed columns dominate the practice of gas-solid chromatography. WCOT columns are typically up to 100 m... 

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