Standard Gas Mixtures Research Articles

Electrochemical gas chromatographic detection of hydrogen sulfide at PPM and PPB levels.

An electrochemical detector for gas chromatographic analysis of hydrogen sulfide is described and its operating characteristics are discussed. The detector operation is based upon the measurement of the current when hydrogen sulfide is electrochemically oxidized at a diffusion electrode. The lower detectable limit was 3 X 10(-12) grams H2S, the precision was 0.5% and analysis was achieved within 2 minutes. Accuracy was limited principally by the preparation of calibration samples and the availability of standard reference gas mixtures.

A Model Study on the Diffusion and the Dilution of Low Molecular Weight Gaseous Components through Cigarette Paper during Smoking

AbstractThe effects of diffusion and dilution on the concentration of gaseous components have been studied by a model consisting of unlit cigarettes differing in paper porosity and length, and a standard gas mixture. Results are as follows: The difference in the concentration of gaseous components between the front and butt end of the cigarette during the puff increases with cigarette length and paper porosity, and also depends on the diffusion coefficient of respective components through the cigarette paper. These changes could be explained mainly by the diffusion loss through the paper in the case of the cigarette with ordinary paper, but by both dilution with air through the paper and diffusion loss in the case of the cigarette with perforated paper. Subsequently, the levels of gaseous components such as carbon monoxide in the exit stream become lower in the Iatter cigarette. In addition, the following equation, which can fully account for these changes, has been derived:where C1i and C0i are the concentrations of the component i at the front and butt end, respectively, L the cigarette length, r the cigarette radius, s the thickness of paper, U0 and U1 the apparent linear gas velocities at the butt and front end, respectively, and Di the diffusion coefficient of component i through the paper.

Mole concentration ? The basis for expressing the quantitative composition of standard gas mixtures

Mole concentration ? The basis for expressing the quantitative composition of standard gas mixtures

Pure gases for standard gas mixtures

Pure gases for standard gas mixtures

Standard vapour mixtures by means of a multi‐capillary flow‐proportioner

AbstractA dynamic method is described for the preparation of standard gaseous mixtures of condensable vapours such as water vapour, gas odorants or hydrocarbons with an accuracy of better than ·5%. The possible concentration range is from a few parts per miliion to saturation level. The method is also suitable for the preparation of multi‐vapour mixtures.

The Preparation of a Standard Gas Mixture of C5and C6Hydrocarbons at a Concentration of 0.05 PPM

Abstract A method for the preparation of a standard hydrocarbon gas mixture in a stainless steel cylinder is described. The mixture was made with twelve C5 and c6 hydrocarbons, liquid at room temperature, in synthetic air at a concentration of 0.05 ppm for each compound. Cylinder wall losses were satisfied by conditioning the wall with all of the compounds. Standard volumes of the equilibrium hydrocarbon vapor-air mixtures were calculated with a formula based on Dalton's Law of Partial Pressure and Amagat's Law of Partial Volume. Standard volumes were withdrawn from special flasks and transferred into the cylinder. Gas chromatographic analyses of the hydrocarbons were statistically examined. The standard volume technique, cylinder wall conditioning and analytical results are discussed.

High-resolution readout of multiwire proportional counters using the cathode-coupled delay-line technique

In this article results of work on the cathode-coupled delay-line readout technique are presented. The basic avalanche production mechanisms for magic gas and standard proportional gas are contrasted and their considerable impact on delay-line readout systems is discussed. Results of careful resolution testing of two externally coupled delay-line systems possessing vastly different propagation delays are presented. Results are presented for both magic gas and a standard proportional gas mixture. Magic gas is shown to have considerable advantages both from the point of view of optimizing resolution performance and minimizing the required delay-line propagation delay. For magic gas a minimum ionizing spatial resolution of 100 μm at normal incidence with slow degradation with inclination was measured for a delay-line propagation delay of 11 ns/cm. Much shorter delays are shown to be theoretically possible without loss of resolution.

Standard gas and vapour mixtures for chromatography

Standard gas and vapour mixtures for chromatography

Standard gas and vapour mixtures for chromatography

AbstractStandard mixtures of gases and vapours are prepared gravimetrically with a high degree of accuracy and are used for the calibration of large quantities of multi‐component mixtures which may serve as chromatographic standards for routine analysis of gases and vapours. A dilution method is used for the preparation of very low concentrations such as fractions of a parts/106 of pentane in helium.

Bakeable ionization chamber for low-level tritium counting

Abstract In order to minimize background and facilitate decontamination we built a cylindrical ionization chamber using ultrahigh-vacuum metallic seals. Sapphire and pure alumina insulators isolated the collector electrode from the chamber. The chamber and inlet lines are bakeable to 450°C and withstand pressures up to 3 atm. The unshielded background of a new chamber was 2 fA. The operating voltage plateau of the chamber was determined at 20 and 764 torr. We calibrated output current vs total tritium content, using tritiated methane and a tritium-argon mixture, both by increasing the pressure of a constant-concentration standard and by diluting the standard gas mixture at vonstant pressure. Theoretical calculations of efficiency of beta-energy absorption in spherical vessels filled with several gases are presented, as well as experimentally determined chamber efficiencies for methane and argon.

Factors affecting the precision and accuracy of Po 2, measurements using the clark electrode

The results of a laboratory quality control survey for Po 2 estimation are given. The scheme was based on the interchange between laboratories of blood specimens arriving for routine analysis, of partially equilibrated blood samples, and of oxygen-nitrogen gas mixtures. The analytical results of these samples were used to detect and quantitate errors in the measurement of Po 2. A major cause of both systematic and random errors in the Po 2 results was found to be the technique of sampling standards for calibration of the electrode. Different methods for calibrating the oxygen electrode were compared by analysing standard oxygen-nitrogen gas mixtures. The results showed that atmospheric air is a reliable standard, and that oxygen-nitrogen gas mixtures provide a convenient and accurate means of assessing the precision and accuracy of routine Po 2 measurements.

Preparation of Mixtures for the Calibration of Gas Analysers

Differential gas analysers for use in photosynthesis experiments can be calibrated with the same accuracy as that specified for the single standard gas mixture that is required. With the use of only one gas mixing pump, the composition of a mixture can be specified to better than ±1 per cent, compared with ±5 per cent usually offered by commercial gas suppliers.

Applications of gas chromatography to anaesthesiology. 1. Gases and vapours.

Analysis of anaesthetic gases and vapours by gas chromatography is accurate, simple, and fast. Most of the agents possess thermal conductivities of sufficient magnitude so that a small change in the composition of a mixture produces sufficient change in the chromatogram to allow accurate analysis. There can be no doubt that physical methods of analysis are more accurate and less tedious than the time-honoured chemical procedures. The majority of the physical analytical techniques require expensive, complicated, fickle instrumentation, which in turn must be operated by trained, skilled technicians. Gas chromatography, utilizing a thermal conductivity detector, while hardly inexpensive, is a relatively simple technique which can be mastered by the average technician in a matter of hours. As is the case in all analytical techniques, the accuracy and reproducibility of the determination is dependent upon the accuracy with which standard gas mixtures can be prepared. This is the limiting factor in the effective use of this technique. It should be emphasized that in spite of statements to the contrary, this is essentially a research tool and at present has no place in the monitoring of the routine clinical anaesthetic. The application of this technique, in anesthesiology, is currently limited to analysis of volatile and gaseous agents, and fixed respiratory gases. The horizons, however, are unlimited. Barbiturates, phenothiazines, narcotics, amino acids, and amines of biological interest can all be quantitated by slight modifications of the chromatographic technique described.

A Method to Make Standard CO2Samples for Infrared Gas Analysis and the Operation of an IRGA Analyser for Air Samples from the Scandinavian Network

A method of making CO 2 standard gas mixtures varying between 1 and 400 ppm in concentration with an accuracy of ± 1 ppm is described. An accurately known volume of pure CO 2 gas is mixed with CO 2 free dry air in an evacuated vessel. A method to take samples from this vessel and to analyse the samples in an IRGA gas analyser is described. The use of the apparatus for the Scandinavian CO 2 network is described. DOI: 10.1111/j.2153-3490.1960.tb01304.x

A Method to Make Standard CO<sub>2</sub> Samples for Infrared Gas Analysis and the Operation of an IRGA Analyser for Air Samples from the Scandinavian Network

A method of making CO2 standard gas mixtures varying between 1 and 400 ppm in concentration with an accuracy of ± 1 ppm is described. An accurately known volume of pure CO2 gas is mixed with CO2 free dry air in an evacuated vessel. A method to take samples from this vessel and to analyse the samples in an IRGA gas analyser is described. The use of the apparatus for the Scandinavian CO2 network is described.