Capillary column separation number

There are a variety of liquid phases available for both packed and capillary columns. In packed columns, these are coated onto a solid support in capillary columns they are coated onto the capillary column wall. At the height of packed column use, there were over 200 liquid phases in common use. With the much higher separating power of capillary columns, this number has dropped to five most common liquid phases with perhaps two dozen specialty materials. A summary of common liquid phases and their application is shown in Table 14.5. The capillary column and instrument vendors also have extensive information on how to properly use packed and capillary columns and on applications available in their literature and on their WWW-sites. ... 

Used in virtually all organic chemistry analytical laboratories, gas chromatography has a powerful separation capacity. Using distillation as an analogy, the number of theoretical plates would vary from 100 for packed columns to 10 for 100-meter capillary columns as shown in Figure 2.1. 

A chromatographic column provides a location for physically retaining the stationary phase. The column s construction also influences the amount of sample that can be handled, the efficiency of the separation, the number of analytes that can be easily separated, and the amount of time required for the separation. Both packed and capillary columns are used in gas chromatography. 

It is for this reason that not only the various Sulfur-containing groups present, but also the mono- and dimethyl-substituted species of benzothiophenes and dibenzoth-iophenes have to be separated and quantified individually. As the number of sulfur compounds present in (heavy) middle distillate fractions may easily exceed 10 000 species, a single high resolution GC capillary column is unable to perform such a separation. 

Packed columns are still used extensively, especially in routine analysis. They are essential when sample components have high partition coefficients and/or high concentrations. Capillary columns provide a high number of theoretical plates, hence a very high resolution, but they cannot be used in all applications because there are not many types of chemically bonded capillary columns. Combined use of packed columns of different polarities often provides better separation than with a capillary column. It sometimes happens that a capillary column is used as a supplement in the packed-column gas chromatography. It is best, therefore, to house the capillary and packed columns in the same column oven and use them selectively. In the screening of some types of samples, the packed column is used routinely and the capillary column is used when more detailed information is required. 

The influence of HPLC on the development of separation media for CEC is rather obvious. For example, HPLC-like hardware , such as frits and packed columns, are employed. A number of various packing technologies have been reported that enable packing particles into narrow bore capillary columns. The solvent slurry packing appears to be the most popular technique that has been transferred di-... 

CZE has been employed for the analysis of another set of dyes in foodstuffs. The chemical structures, numbers and names of the dyes included in the investigation are listed in Fig. 3.142. A fused-silica capillary column of 57 cm length (50 cm effective length 75 jum i.d.) was employed for the separations. The capillary was conditioned by 1.0 M NaOH for 20 min followed by 10 min wash with water and 10 min wash with the running buffer. The buffer was prepared by adding NaOH to 10 mM phosphoric acid to reach pH 11.0. The capillary was thermostated at 25°C and the separation voltage was 20 kV. A hydrodynamic injection mode was applied (0.5 psi, 4 s, 21 nl) and spectra of... 

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