Wall-coated Open Tubular Research Articles

The efficiency of open tubular gas chromatographic columns

A new parameter, the mean specific plate number, is proposed for assessing the efficiency of support coated open tubular (SCOT) and wall coated open tubular (WCOT) columns and for comparing the efficiency of different open tubular columns. It has the advantage over most previously used parameters in that it has only a small dependence on the partition ratio and it allows for the column diameter.

Determination of sulfur-containing gases by a deactivated cryogenic enrichment and capillary gas chromatographic system

A deactivated glass capillary, wall-coated open tubular (WCOT) column is the heart of a novel gas chromatographic procedure for measuring reduced sulfur-containing gases in air samples. These deactivated, high resolution WCOT columns provide optimal chromatographic separation of compounds such as H/sub 2/S, COS, CH/sub 3/SH, CH/sub 3/SCH/sub 3/, CS/sub 2/, CH/sub 3/SSCH/sub 3/, and other organosulfur species. In addition, the combination of WCOT columns, a deactivated GC, and the flame photometric detector (FPD) increases the sensitivity of the GC/FPD method for sulfur compounds. The GC/WCOT/FPD instrumentation is also designed for complete compatibility with a cryogenic sampling procedure. This surface-deactivated, cryogenic enrichment system has been shown to provide known sampling efficiencies between 40% to approximately 100% for the important inorganic and organosulfur compounds at the low and sub-ppB concentrations. The methodology described has been successfully applied to field analyses of sulfur compound emissions from biogenic sources.

Static coating of capillary columns: Some practical considerations

Some of the practical problems involved in the preparation of wall-coated open tubular (WCOT) glass columns have been examined, and precautions are described to overcome or minimize these problems when non-polar silicone gums are used as the stationary phase. Modifications have been made that simplify the preparation of WCOT columns. The labour involved in cleaning an old column and recoating it amounts to about 2 h work, plus monitoring those steps that proceed automatically. About half this time is spent in cleaning the old column.

Separation and identification of polynuclear aromatic compounds in coal tar by using glass capillary chromatography including combined gas chromatography-mass spectrometry

Glass capillary chromatography combined with mass spectrometry has been used for the qualitative analysis of high-temperature coal tar. A simple method for making thermally stable wall-coated open tubular (WCOT) columns coated with the stationary phase SE-54 is described. More than 140 components with boiling points up to 870°K could be separated and identified or characterized. A typical pattern for polynuclear aromatics (PNAs) was found on columns having polarities ranging from the polar polyphenyl ether sulphone Poly S 179 to the less polar silicone liquids OV-61, OV-7 and SE-54. Comparison of the retention times of more than 40 standard compounds contained in a single test mixture enabled most of the major constituents to be assigned. A number of compounds that had not hitherto been reported to be constituents of coal tar were characterized by their mass spectra. These included two unknown compounds in the benzpyrene fraction. Coal tar may now serve as an inexpensive but very complete mixture for the gas chromatographic analysis of PNAs, because the retentions and/or orders of elution of a large variety of PNAs obtained on WCOT columns coated with various stationary liquids of different polarity have now been established.

Evaluation of Relative Retention Reproducibility on Wall-Coated and Support-Coated Open Tubular Columns

Relative retention data calculated from test chromatograms obtained on wall-coated open tubular (WCOT) and support-coated open tubular (SCOT) columns in a period of one year are statistically evaluated. The data prove the excellent reproducibility of open tubular columns and that data obtained on either column type are interchangeable.