Columns high-speed

It is seen from Figure 15 that the analysis time ranges from about 10,000 seconds (a little less than 3 hr) to about 30 milliseconds. The latter, high speed separation, is achieved on a column about 2 mm long, 12 microns in diameter, operated at a gas velocity of about 800 cm/second. Such speed of elution for a multicomponent mixture is of the same order as that of a scanning mass spectrometer. 

The advantages of monosized chromatographic supports are as follows a uniform column packing, uniform flow velocity profile, low back pressure, high resolution, and high-speed separation compared with the materials of broad size distribution. Optical micrographs of 20-p,m monosized macroporous particles and a commercial chromatography resin of size 12-28 p,m are shown in Fig. 1.4. There is a clear difference in the size distribution between the monodispersed particles and the traditional column material (87). 

The packed columns of Shodex OHpak SB-800HQ series are packed with polyhydroxymethacrylate gels and are designed for use with high-resolution, high-speed aqueous size exclusion chromatography. The packed columns are best suited for the analysis of water-soluble polymers and proteins (Table 6.8). 

C. A. Monnig and J. W. Jorgenson, On-column sample gating for high-speed capillary zoneelectiophoresis . Awn/. Chem. 63 802-807 (1991). 

Z. Fiu and J. B. Phillips, High-speed gas chr omatography using an on-column thermal desorption modulator , /. Microcolumn Sep. 1 249-256 (1989). 

The small peak volumes typical of samples eluted from small bore columns and short small diameter particle columns used in high-speed liquid chromatography place severe demands on the dispersion characteristics of all components of the liquid chromatograph. The standard deviation of a peak eluting from a column is given by... 

High speed separations, particularly with narrow-bore HCOT columns of 100 aicroneters or less, places special demands upon the instrument design [131,134,148-150]. The gas chromatograph... 

Membranes offer a format for interaction of an analyte with a stationary phase alternative to the familiar column. For certain kinds of separations, particularly preparative separations involving strong adsorption, the membrane format is extremely useful. A 5 x 4 mm hollow-fiber membrane layered with the protein bovine serum albumin was used for the chiral separation of the amino acid tryptophan, with a separation factor of up to 6.6.62 Diethey-laminoethyl-derivatized membrane disks were used for high-speed ion exchange separations of oligonucleotides.63 Sulfonated membranes were used for peptide separations, and reversed-phase separations of peptides, steroids, and aromatic hydrocarbons were accomplished on C18-derivatized membranes. 

Figure 6 High-speed tryptic fingerprint. Horse cytochrome c was digested with trypsin and the peptide chromatographed in acetonitrile water 0.1% TFA at various temperatures and flow rates on a 15 x 0.2-cm PS-DVB column packed with 3-p, 300-A particles, (a) 26°C and 0.5 ml/min. (b) 42°C and 0.7 ml/min. (c) 70°C and 1.1 ml/min. Detection at 220 nm. Note that the resolution rises with the speed of separation.89 (From Swadesh, ]., BioTechniques, 9, 626, 1990. With permission.)...

Figure 18 Very-high-speed gradient anion exchange chromatography of proteins. Column 0.46 x 3.5 cm ZipSep AX, 3 p. Eluent Tris-HCl, pH 8.0, operated on a gradient from 0-0.5 M NaCl. Flow rate 2ml/min. Detection UV absorbance at 280 nm. (1) Ribonuclease A, (2) carbonic anhydrase, (3) conalbumin, (4) bovine serum albumin. (Reproduced from Hatch, R. G., J. Chromatogr. Sci., 31, 469,1993. By permission of Preston Publications, A Division of Preston Industries, Inc.)...

General texts on GC are numerous [118,119] narrow-bore GC was addressed by van Es [120]. Sample introduction techniques and GC inlet systems have been reviewed [25,90] and split/splitless [121] and on-column injection [122] were considered specifically. Stationary phases [123], multiple detection [103], derivatisation [124,125], and quantitative analysis in GC [109] have been described. High-speed GC has recently been reviewed [126]. For a compendium of GC terms and techniques, see Hinshaw [127]. 

Dry column chromatography [528] provides several improvements over traditional column chromatography, such as better resolution and high speed. Another important characteristic is the near-quantitative applicability of TLC results in dry column analysis. Knowledge of the TLC characteristics of a sample is useful before column chromatography is employed. Careful control of the moisture content of the adsorbent is crucial to the dry column as well as other types of chromatography. 

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