Glass capillary columns for separation of free organic acids

Glass capillary columns have been prepared without acidic additive in the stationary phase, from which free organic acids elute as sharp and symmetrical peaks. The required surface in the borosilicate glass capillary was generated by a combination of leaching with aqueous HCl and deposition of colloidal silica particles; it can be coated with stationary phases have a broad range of polarity. Aqueous samples containing free organic acids can also be analyzed in such columns in an isothermal mode.     

Advancing the chromatography of GC/FT-IR to WCOT capillary columns

By the use of a wide-bore WCOT capillary column, it was possible to obtain the first on-the-fly GC/FT-IR spectra with a WCOT column. This wide-bore WCOT column gave improved separation, as compared to a SCOT column, and yielded identifiable infrared spectra for a real sample.     

Gas-liquid chromatography of serum bile acids using glass capillary columns

The proposed combination of a rather simple procedure for sample preparation with capillary gas-liquid chromatography using a barium carbonate/polyethyleneglycol 20,000 column and a Grob-type on-column injector permits measurement of bile acids in serum with high separation efficiency, short analysis time and complete separation of bile acids from cholesterol. The method can be adapted to combined capillary gas-liquid chromatography - mass spectrometry.     

Preparation of glass capillary columns coated with immobilized OV-240-OH (33% cyanopropyl substituted,OH-terminated). An approach to improve the inertness and thermal stability of cyanoalkyl polysiloxane coatings

Coating intensely leached glass capillaries with OV-240-OH, the most polar commercially available OH-terminated polysiloxane phase at the present time, is described. Beside chemical bonding of the phase via condensation with silanol groups of the support, additional immobilization using dimethyltetramethoxysiloxane as a crosslinker is carried out. After in situ methylation of the immobilized coating, and transformation of acidic impurities of the cyanopropyl substituted phase into the respective methyl esters, increased inertness of the column was observed. Working instructions are given, and processes involved are discussed.     

The use of glass and fused silica open tubular columns for the separation of structural,configurational, and optical isomers by selective complexation GC: Sec-alcohols and ketones

The use of glass and fused silica open tubular columns for selective separation of structural, configurational, and optical isomers (enantiomers) of underivatized aliphatic alcohols and ketones by complexation gas chromatography on optically active metal chelates is described. The method represents a powerful analytical tool for the precise determination of diastereomeric (d.e.) and enantiomeric (e.e.) excesses in asymmetric syntheses and in natural product characterization. The direct screening of the enantiomeric composition and absolute configuration of terpinene-4-ol, the aggregation phermone of Polygraphus poligraphus (L), is described.     

Characteristics and performance of gas chromatographic detectors with glass capillary columns

A comparison of the characteristics and Performance of the flame ionization, electron capture, and flame photometric detectors with capillary columns is described. Factors which may affect the limits of detection, linearity, chromatographic peak shape, and other detector performance characteristics are discussed and compared with the results of a model derived for the behavior of concentration and mass flow-rate dependent chromatographic detectors used with capillary GC systems. Examples are given of highly complex and labile mixtures such as pesticide residues and products from coal hydrogenation.     

High resolution glass capillary columns for the gas chromatographic analysis of alditol acetates of neutral and amino sugars

The development of improved high resolulation glass capillary columns for separating the alditol acetates of neutral and amino sugars is described. Different capillary column treatments were evaluated for their activity toward amino sugar derivatives and for their effect on the efficiency of the completed column. The simple two-step procedure of leaching with aqueous hydrochloric acid and dynamic coating with SP-2330 was found to produce efficient and inert columns.     

The preparation of thick-film glass capillary columns

A detailed method for the routine preparation of glass capillary columns is presented. The method consists of coating a glass tube with quartz powder prior to pulling the tube into a capillary. The inner surface of the capillary consists of an even distribution of quartz particles fused to the walls. This surface has been found readily deactivated by standard procedures and ideal for the preparation of thick-film glass capillary columns. The method has been thoroughly tested in two independent laboratories to ensure that the procedures described are reproducible.     

Design of a microprocessor-controlled automated injection system for the analysis of gas phase cigarette smoke using glass capillary columns

An automatic injection system for the analysis of gas phase smoke has been designed and evaluated using the microprocessor-controlled Hewlett-Packard 5830 gas chromatograph. The cryogenic preconcentration trap was constructed from relatively inexpensive and readily available materials. It was determined that the use of the preconcentration trap, as opposed to condensing the smoke on the head of the cold (-50°C) chromatographic column, significantly enhanced the resolution of the more volatile gas phase components. Data are presented which illustrate the injection system characteristics. In addition, chromatograms of gas phase smoke are presented which demonstrate the effectiveness of this technique.     

Advances in the preparation and evaluation of GC capillary columns

The preparation of (glass) capillary columns of high quality is still not without difficulties. Six problems in this context are highlighted. Column material choice(l), glass wall modification(2) and coating(3) are considered to have reached a satisfactory level. Deactivation(4) is still in a state of flux. Quantitation(5) is the least satisfactory aspect of capillary GC. Scope expansion(6) will be helped by the introduction of new phases of high thermal stability and by the adoption of solutions exclusively applicable to capillary GC. Evaluation of (glass) capillary GC columns is a rapidly developing field. Hopefully the number and complexity of test or polarity mixtures will not expand much further and it will be possible to make a clear and generally acceptable choice. The preparation and evaluation of ever-improving capillary columns is important to an ever-widening group of chromatographers. Our opinion on selected topics in this already vast field is summarized in the following overview.     

Preparation of inert glass capillary columns coated with UCON 50 HB-5100. An attempt to rediscover industrially produced α, ω-polyethylene/polypropyleneglycol ethers as stationary phases in capillary gas chromatography

Using UCON 50 HB-5100, one of the most successful stationary phases in capillary gas chromatography during the past decade, as an example, we wish to redirect attention to the excellent properties of the polyethylene/polypropyleneglycol ether copolymer coatings. Based on experience gained in work with OH-terminated polysiloxanes, a method is described for preparing inert and relatively temperature stable chemically bonded and crosslinked coatings in a single working step. Methyltrimethoxysilane was used as coupling agent, and trifluoroacetic acid was introduced as an acidic catalyst. The reaction mechanisms involved as well as the influence of additional crosslinking on the column behavior are discussed, particularly with respect of the inertness of the coatings.     

Analysis of polar compounds on PEG-40M/KF glass capillary columns

The chromatographic properties of potassium fluoride as an additive to the polyethylene glycol stationary phase were investigated. This unique base in organic chemistry was shown to succeed in yielding good results for the analysis of polar compounds, including the primary amines. Glass capillary columns of high selectivity for primary and secondary aliphatic amines were obtained by the “hexane plug” procedure by which a thin layer of KF is deposited on the inner surface of glass capillary columns. Some possible types of donor-acceptor interactions occuring within the system PEG/KF/solute were considered.