K. Tesařík

Flow characteristics and technology of capillary columns with inner diameters less than 15 μm in liquid chromatography

Abstract The flow characteristics of capillary columns at flow-rates up to 10 −5 μl/sec have been studied experimentally as a function of the column diameter and of the pressure drop. Theoretical conclusions based on the Poiseuille equation and band broadening for unsorbed solutes have been tested. The preparation of glass capillary columns is described, and the role of the glass melting temperature is discussed. The inner diameters (5–34 μm) of the columns were measured both by microscopy and hydrodynamically. The maximum difference between the two measurements was 2.8 μm, but in most cases it did not exceed 1.5 μm. The modified flame-ionization detector was used.

Open tubular columns in liquid chromatography

Abstract Capillary liquid chromatography was studied in liquid-solid and liquid-liquid systems. It was proved that selectivity data obtained with an analytical column are the same as those obtained with a capillary column having a layer of adsorbent on its wall. In the liquid-liquid system, up to 1,250,000 theoretical plates were obtained for an unretained solute with an effectiveness of 50 theoretical plates per second. Possibilities of applying commercial pumps and detectors to the work with capillary columns were demonstrated.

Correlation of the boiling points of non-branched C9 and C10 olefins with the gas chromatographic retention indices

Abstract A correlation was made between the boiling points of fourteen non-branched nonenes and decenes and the retention indices, and also a comparison of the results obtained by known methods of calculation with the available tabulated data. The gas chromatographic measurements were carried out on a 200-m long capillary column (stainless steel) coated with squalane at 86, 100 and 115° and permitted boiling points to be determined with a reproducibility of ± 0.1°. Substantial deviations were found from the Kovats rule δI ≈ kp δTb for the behaviour of isomeric hydrocarbons on a non-polar stationary phase. In the case of the olefins studied, the proportionality constant, for which a value of approximately 5 is stated in the literature, fell within the range 1.8–13.9 on squalane. The correction factor fc used for the calculation of IB by M atukuma is constant only in the case of trans-alkenes, whereas for cis-alkenes and I -alkenes it is dependent on the number of carbon atoms in the olefin molecule.

Separation of pyridine bases of coal tar light oil by means of capillary gas chromatography

Abstract The suitability of glass capillary columns coated with polyethylene glycol 400, polyethylene glycol 400 mixed with 2% potassium hydroxide, Apiezon K mixed with Slovamin 20, Amine 220, and Reoplex 400 stationary phases for the separation of pyridine, aniline, and quinoline derivatives was studied. Optimal conditions for the separation of these compounds were determined and the dependence of the chromatographic behaviour of some derivatives of pyridine and aniline on their structures was verified.

Influence of surface tension on the homogeneity of the film of stationary phase in glass capillary columns

Abstract The surface tensions of glass, stationary liquid and solven affect the mode in which the film of a stationary phase is deposited on glass columns. The effects of the surface tensions of polar liquids and of the internal surface finish of the glass capillary formed before coiling on the quality of the film were studied. A procedure involving the so-called wettability coefficient is proposed for the evaluation of capillaries with surfaces modified prior to coating with a stationary phase.

Critical operating parameters of the fluid grading method

Abstract Optimum conditions were found for the grading of chromatographic supports and packings. The standard deviation of the graded fraction with a diameter of 25 μm was ± 2.5 μm at the pressure regulation attained. An optimum period of time was suggested for the grading of one fraction as well as for the distribution of a sample into a greater number of narrower fractions. A critical volume of sample was determined so as to enable the device to provide the maximum output.

Glass capillary gas chromatography of homologous series of esters : V. Separation of halogenoacetates of C1C16 aliphatic alcohols and 2-halogenoethyl esters of C2C16 aliphatic acids with the same molecular weight on an SP-400 glass capillary column

Abstract The gas chromatographic separation of halogenoacetates of C 1 C 16 aliphatic alcohols and 2-halogenoethyl esters of C 2 C 16 aliphatic acids and comparisons of retentions of pairs of these esters having the same molecular weights has been studied on SP-400 glass capillary columns. The influence of the type of halogen atoms, their number and their positions in esters on their retention was examined. Kovats retention indices were used to interpret the results.

Immobilized stationary phase on the basis of polyethylene glycol cross-linked with pluriisocyanates of the Desmodur type

SummaryThe preparation of an immobilized stationary phase based on Carbowax 20M is described. The stationary phase cross-linking was carried out with Desmodur N 75 or Desmodur L 75, pluriisocyanates. The properties of the prepared stationary phases are compared.

Grading of chromatographic supporst and packings according to particle size by the fluid method

Abstract Supports and packings for chromatography were graded by the flotation of individual particles in a constant stream of gas or liquid. By gradual increase in pressure, fractions containing particles of a particular size were separated and isolated. The sharpness and the reproducibility of the separation were studied. The effect of particle shape on the sharpness of separation was investigated.

Preparation of glass capillary columns for liquid chromatography

Abstract Procedures were tested for the preparation of capillary columns for liquid-solid and liquid-liquid systems. A layer of silica gel of thickness 0.3–50 μm is formed by the reaction between a solution of ammonia and tetramethylammonium hydroxide, which even permits coating with a liquid stationary phase.