Glass capillary columns development

Capabilities of capillary GC extend well beyond the analysis of complex mixtures. The use of capillary columns is reflected in a more effective trace analysis, unique detection capabilities, and a more reliable GC/MS. While much important biochemical work has already been done with glass capillary columns, development of... 

There is considerable current interest in development of state-of-the-art methodology for characterization of PAHs in various matrices (.l). Gas chromatography and gas chromatography-mass spectrometry are two techniques widely used for PAH analysis because the necessary equipment is available in most laboratories. The development of high resolution glass capillary columns has significantly advanced the compound-characterizing capability of these techniques. 

Schomburg, G. Diehlmann, R. Husmann, H. Weeke, F. New developments with glass capillary column production and sampling techniques. Chromatographia 1977, 10, 580. 

The polymer is deposited as a uniform annular coating in a glass capillary column. A solute is injected into an inert carrier gas that flows through the column. The elution curve of the sample is then used with a model to determine the solute activity and diffusivity in the stationary phase. A detailed description of the equipment and the experimental procedure is given by Pawlisch (361. It is of value to present the model used to describe the process. The description provided by Pawlisch (361, given below, indicates how the model was developed. 

Huhtikangas et al. used also glass capillary columns for quantitative determination of morphine in plasma levels. A relative simple method was developed based on extractive alkylation of morphine with pentafluorobenzyl bromide. A glass capillary, 18 m by o.35 mm I.D. coat ed with 0V-225, and nalorphine as internal standard were used. The detection limit with FID... 

Chemical modification of surface silanol groups on the glass surface affects both the spreading of liquid films [97] and the residual adsorptive properties of glass capillary columns. Thus, the surface wettability problems can largely be solved through different individual surface treatment techniques, or their combination. Most of the recent developments in this area have been reviewed [100]. 

Whereas the primary objective of a great many GC plasma steroid determinations is to measure one or just a few compounds, modem GC permits determination of the entire profiles of substances. Novotny et al. [115] utilized glass capillary columns combined with sample preconcentration to develop multiple profiles of different steroid conjugates from 1-5 ml plasma samples. Capillary GC and mass-fragmentographic detection were used by Axelson and Sjbvall [256] to monitor selectively the profiles of 3-ketosteroids in plasma from women in different stages of pregnancy. 

LtPSKY, S. R. Duffy, M. L. 1986a. High temperature gas chromatography the development of new aluminum clad flexible fused silica glass capillary columns coated with thermostable nonpolar phases Part 1. Journal of High Resolution Chromatography, 9, 376-382. 

An example of the separation of a methane-iso-butane-n-butane mixture with splitless injection of 0.5 ml of the sample into a glass capillary column with a silica layer is given in paper [26]. The analysis time is less than 1 min. Incidentally, splitless injection of a sample was already used in an earlier period of adsorption capillary column development (see, for example, Fig. 3-4 [70]). 

Most of the reported applications of this technique involve the direct resolution of derivatised enantiomers on chiral stationary phases. The earliest successful resolution of yV-trifluoroacetyl amino acid esters on glass capillary columns coated with N-trifluoroacetyl-5-isoleucine lauryl ester (2) was effected in 1966. Superior stationary phases developed quickly, such as (3), in which the additional amide bond may interact via hydrogen bonding. These chiral supports work well for the separation of A -perfluoracylated derivatives of a given amino acid. However, their low thermal stability (190 C maximum) and appreciable volatility have inhibited their use for the simultaneous... 

Gas chromatography (GC) was first described in 1952 by James and Martin [1] with the separation of a mixture of small carboxylic acids. Initially, packed-column GC columns were applied. The power of GC was substantially enlarged by the introduction of open capillary columns in 1958 by Golay [2]. In most cases, fragile glass capillary columns were applied. As such, the introduction of the fused-sUica capillary column in 1976 by Dandeneau and Zerenner [3] can be considered as a major breakthrough in the development of GG. 

As with capillary columns, it is crucial to have an inactive surface and maintain a reasonably even temperature over the length of the interface. This is usually accomplished by using only glass in the interface. The additional connections necessary in an enrichment-type interface present new areas for leaks to occur. Connections are especially prone to develop leaks after a cooling/heating cycle. 

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