Gas analysis method

Analytical Methods. Molybdenum contents in ore concentrates and technical oxide are most accurately deterrnined gravimetricaHy by precipitating lead molybdate. Molybdenum content is usually not determined on pure compounds or metal. Instead, spectrographic methods are used to measure impurity elements that must be controlled. Carbon and oxygen in metal products are measured by standard gas analysis methods. 

Diem D, Kerfoot H, Ross B. 1988. Field evaluation of a soil-gas analysis method for detection of subsurface diesel fuel contamination Second national outdoor action conference on aquifer restoration, ground water monitoring and geophysical methods. National Water Well Association Dublin, OH. 

This study demonstrates high efficacy and expediency of the TCNQ derivative-based point-contact multistracture as a prospective asset for development of new sensors. The complex character of the sensors response curve and correlation of some response characteristics with different pathological manifestations in human breath, may be further used as a noninvasive diagnostic method alternative to some invasive approaches currently routinely used in clinic. The need for reliable and feasible gas analysis methods functional in presence of atmospheric air, opens opportunities for application of the proposed sensor technique in other spheres of human activity. High sensitivity of the point-contact multistructure enabling analysis of composite gas mixtures, opens up wide possibilities to apply the demonstrated approach for environment and health protection, such as detection of trace amounts... 

Determination of formaldehyde release. Part 2 Formaldehyde release by the gas analysis method... 

As can be seen from Figure 27.13, the permeability measurements of Nafion-like membranes do vary considerably, probably because the state of the membranes is difficult to control (e.g., the dryness of the membrane). There is a pronounced difference in the permeabilities for wet and dry membranes, but the method of measurement does not yield consistent variation in the measured values. It can therefore be concluded that the electrochemical method is equivalent to the gas analysis method, even though the measurement conditions are different from those in fuel cell applications. 

E. Kaiserberger (Ed.), Special Issue Coupling Thermal Analysis and Gas Analysis Methods, Thermochim. Acta, 295 (1997) p. 1-186. 

The detection of a small amount of Na CO can be done using a gas analysis method. This method is based on the principle of CO being released from acidified carbonate solution. A special glassware assembly should be used for the accurate measurement of CO, released. 

The purpose of this study was to evaluate laboratory formaldehyde release test methods for predicting real-life formaldehyde air concentrations human exposure levels, and health risk. Three test methods were investigated the European perforator test, the gas analysis method at 60 C and 3% RH, and the gas analysis method at 23 C and 55% RH. Different types of particleboard bonded with urea-formaldehyde and urea-melamine-formaldehyde resins were tested. The results were used to rank boards as a function of test method, conditioning, short-term humidity, and temperature variations during storage. Additional experiments were conducted in small experimental houses at a Dutch research institute. Our conclusions are that relative ranking of products is influenced by the test method and by change in relative humidity. The relationship between test method and release in real-life situations is not clear. In fact, it seems impossible to use laboratory measurements to predict real-life product performance of board if the board is not fully in equilibrium with the atmosphere. 

We have to note that the two melamine-urea-formaldehyde boards do not satisfying this theory. This difficulty excepted, the curve family obtained fits without fault. However, we can say that for a loading rate of 0.5, near that used in the foregoing test, we should obtain a similar ranking, in spite of an inversion between two panels. However, a correlation factor between the two gas analysis methods does not exist, because the values are as follows ... 

Figure 1. Comparison of board classification according to the perforator method and the gas analysis method.

The incidence of perceptible formaldehyde in homes, offices and schools has caused widespread uncertainty about the safety of living with formaldehyde. This uncertainty was enhanced by the large scale installation of urea formaldehyde foam insulation (UFFI) because a substantial part of this material was made from small scale resin batches prepared under questionable quality control conditions, and was installed by unskilled operators (10). The only reliable way to avoid such uncertainty is to know the emission rate of products and develop a design standard that allows prediction of indoor air levels. The first and most important step in this direction was achieved with the development and implementation of material emission standards. As indicated above, Japan led the field in 1974 with the introduction of the 24-hr desiccator test (6), FESYP followed with the formulation of the perforator test, the gas analysis method, and later with the introduction of air chambers (5). In the U.S. the FTM-1 (32) production test and the FTM-2 air chamber test (33) have made possible the implementation of a HUD standard for mobile homes (8) that is already implemented in some 90% of the UF wood production (35), regardless of product use. 

Kaisersberger, E., Ed., Thermal analysis and gas analysis methods, special issue, Thermochim. Acta 295, 1-186, 1997. 

The formaldehyde content of all samples was determined according to EN 120 (perforator method) and the formaldehyde emission was determined for some samples according to EN 717-2 (gas analysis method). 

A HS gas analysis method for the determination of volatile hydrocarbons in sealed containers was described by Loliger (1990). The experimental setup consists of a gas chromatograph equipped with a gas sampling valve, a vacuum pump and a manometer. The sampling system is evacuated to c. 1 mbar, the tin is punctured by a stainless steel plunger, the gas is left to reach equilibrium and a HS sample is subsequently transferred by means of the valve to a column packed with activated alumina. This system allows estimation of Ci-C6 hydrocarbons, which represents final and stable secondary oxidation products, and was applied to various food systems ranging from oils and emulsions to frozen meats and dehydrated cereals, potatoes and milk. 

Gas Chromatographic Blood Alcohol Determination by the Head Space Gas Analysis Method... 

Filling stations for electronic gases are equipped with particle filters, products liquefied under pressure are filled by application of a distillation step. In addition, adsorptive cleaning methods are often applied (see also Section 9.2.4). Regarding the gas analysis methods used in quality control, apart from the already described methods for specialty gases, the field of metal-trace analysis has to be emphasized. 

The methods with the greatest potential are those for which the procedure is simple and which can be freed from interference with little modification. The gas-analysis methods are of particular interest in that the procedure can be... 

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