Manometric methods

Various aspects of in vitro gas production test have been reviewed by Getachew et al. [33], and these authors reported that gas measurement were centered on investigations of rumen microbial activities using manometric measurements and concluded that these methods do not have wide acceptability in routine feed evaluation since there was no provision for the mechanical stirring of the sample during incubation. Another in vitro automated pressure transducer method for gas production measurement was developed by Wilkins [34], and the method was validated by Blummel and Orskov [35] and Makkar et al. [36]. There are several other gas-measuring techniques such as (i) Flohenheim gas method or Menke s method [37] (ii) liquid displacement system [38] (iii) manometric method [39] (iv) pressure transducer systems manual [40], computerized [41], and combination of pressure transducer and gas release system [42]. 

Carbon dioxide is not a common oxidation product in periodate work, but it does appear in the oxidation of ketoses,49 a-keto acids,14,39 and a-hydroxy acids,14 39 and it is often a product23 141 of overoxidation. Carbon dioxide analyses have been carried out using the Plantefol apparatus,49 the Warburg apparatus,14 23 and the Van Slyke-Neill mano-metric apparatus,39 and by absorption in standard sodium hydroxide141 followed by back-titration with acid. A most convenient method is the very old, barium hydroxide absorption scheme.16 The carbon dioxide is swept from the reaction mixture into a saturated, filtered barium hydroxide solution by means of a stream of pure nitrogen. The precipitated barium carbonate is filtered, dried, and weighed. This method is essentially a terminal assay. The manometric methods permit kinetic measurements, but involve use of much more complicated apparatus. 

A range of different methods measures the solubility of hydrogen in metals and alloys. Manometric methods [98] and gas volumetric methods [99] have been used to determine pressure-composition isotherms at selected temperatures for a range of alloys [100-103],... 

The manometric method using the Warburg apparatus is highly accurate, but complicated, and demands more time than the simple spectrophotometrical assay, its accuracy being equal. 

The manometric methods described (e.g., L7, W3) are based on the uptake of either carbon monoxide or oxygen, the former using MHb as electron acceptor in the presence of toluidine blue, the latter using the dye as the terminal acceptor in a system involving the following reactions ... 

The number of gas molecules can be measured either directly with a balance (gravimetric method) or calculated from the pressure difference of the gas in a fixed volume upon adsorption (manometric method). The most frequently apphed method to derive the monolayer capacity is a method developed by Brunauer, Emmett, and Teller (BET) [1], Starting from the Langmuir equation (monolayer adsorption) they developed a multilayer adsorption model that allows the calculation of the specific surface area of a sohd. The BET equation is typically expressed in its linear form as... 

ISO 2556, Plastics - Determination of the gas transmission rate of films and thin sheets under atmospheric pressure - Manometric method, 1974. 

ISO 1663 1999 Rigid cellular plastics - Determination of water vapour transmission properties ISO 2556 1974 Plastics - Determination of the gas transmission rate of films and thin sheets under atmospheric pressure - Manometric method ISO 6179 1998 Rubber, vulcanized or thermoplastic - Rubber sheets and rubber-coated fabrics - Determination of transmission rate of volatile liquids (gravimetric technique)... 

The first two determinations by radiation absorption require accurate measurements of the extinction coefficients of ozone (a measurement of the absorption efficiency of the incoming radiation at a maximal absorption wavelength) in the ultraviolet and the infrared. Three different principles have been used over the last 20 years to measure the extinction coefficient of ozone in the ultraviolet at 254 nm manometric, decomposition stoichiometry, and gas-phase titration. The manometric method, which is based on pressure measurements of gaseous ozone, requires (in at least one case ) a substantial and somewhat uncertain correction for decomposition and the method of decomposition stoichiometry depends on the pressure change that accompanies the decomposition of ozone to oxygen, 20, 30,. Clyne and Coxon determined ozone... 

Note that manometric methods can also be used with reactions that generate acids. If bicarbonate is a component of the reaction mixture, any acid formed will result in the generation of CO2. Thus, even peptidases, protein-ases, and esterases can be assayed manometrically . Even some phosphotransferases have been assayed with this procedure. See also Eudiometer... 

M. Dixon (1951) Manometric Methods, Cambridge Univ. Press, Cambridge. 

This subsection contains an expanded discussion of manometric methods. See Sec. 8 for other methods. 

The main disadvantage of the method consisted in the condensation of some of the products of decomposition in the tubes connecting the container with the manometer. This was overcome by Taliani [101] in his manometric method. The... 

There is no ASTM standard for manometric methods specifically for rubbers but ASTM D14347 has basic manometric and constant pressure procedures for plastics. The ISO method for plastics, ISO 25568, gives only a basic manometric procedure. 

The isopiestic and manometric methods (units A2j A2.4) for determination of water activity have the limitation of being dependent on fixed laboratory equipment. The electronic-type sensors have advantages of portability, speed, and simplicity of measurement. The characteristics of a sensor depend upon the manufacturer and each instrument must be calibrated separately. The anodized sensors have advantages of ruggedness, small dimensions, and fast response, as well as freedom from large temperature coefficients and less susceptibility to contamination of the lithium chloride conductivity sensors (Smith, 1971). 

For carbonated soft drinks the level of carbonation is a key parameter. If the level of carbonation is too low or too high the overall flavour balance of the product will be disrupted. The level of carbonation can be measured in a number of ways and four are discussed here. The fust is a manometric method published by AO AC for beer (940.17) the second is also a manometric procedure, but is somewhat less complicated than the AOAC procedure. The final two methods use... 

Three methods for determining mineral carbon dioxide in coal were investigated using bituminous coal. The titrimetric method is claimed to be superior to either of the then-used British standard gravimetric or manometric methods (BS 1016). The procedure involves the decomposition of carbonate minerals with hydrochloric acid and absorption of the evolved carbon dioxide in a mixture of benzylamine, ethanol, and dioxan. This mixture forms a stable salt of benzylcar-bamic acid, which is then titrated with sodium methoxide. The method was said to be suitable for all concentrations of carbon dioxide. It is especially accurate for low concentrations, and it is much more rapid than other methods tested. 

The kinetic parameters of thermal decomposition of several 2,5-disubstituted tetrazoles 6 in the gas phase and in nitrobenzene solution have been determined using manometric methods. Limiting stages of the stepwise uni-molecular decomposition that determine the experimental rate of nitrogen evolution include reversible formation and subsequent breakdown of the azo-diazo intermediates 186 (Scheme 15) <1996RCB2094>. 

In plant cell cultures, shake flask culture is an indispensable stage of cultivation. Investigations in a shake flask are very essential and critical to bioprocess scale-up and optimization. We have developed a simple and convenient technique based on the principle of the Warburg manometric method to measure 02 uptake rate (OUR) and C02 evolution rate (CER) of suspended cells in a shake flask culture. This technique has been successfully applied to suspension cultures of Panax notoginseng cells, and some important bioprocess parameters, such as OUR, CER, respiratory quotient (RQ), SOUR and specific CER (SCER), were quantitatively obtained [99]. As long as the environment temperature is strictly controlled to within an error of 0.1 °C, the measuring system is accurate and reproducible, is easy to operate, is economical, and is also able to treat many samples simultaneously. 

Evangelou, V. P, L. D. Whittig, and K. K. Tanji. 1984a. An automated manometric method for differentiation and quantitative determination of calcite and dolomite. Soil Sci. Soc. Am. J. 48 1236-1239. 

The principle of the physical absorption technique we used, is based on the continuous observation of the absorption kinetics of a solute gas by following the total pressure in the gas phase of a stirred reactor closed to both phases (manometric method). This physical technique was first described by Teramoto et al. [1] these authors used it to determine the liquid side mass transfer coefficient k], a. This technique was then employed with success at high pressures and temperatures by different authors [1-6]. For this reason we have selected this method to determine the liquid side as well as the gas side mass transfer coefficient kGa. 

The experimental set-up [7] is shown in figure 1. The main parts are the reactor and the gas mixing chamber, where temperatures are kept constant at 30°C using two thermostatic bathes. Owing to the selected manometric method, we only need measurements of total pressure versus time and in case of diluted C02, of the gas phase composition (gas chromatography). Pressures, gas compositions and temperatures are automatically recorded versus time. 

The physical absorption technique (manometric method) is suitable to determine the liquid side volumetric mass transfer coefficient as well as the gas-side one. Results show that kLa is independant of pressure and depends mainly on the system s hydrodynamics and secondly, that koa is inversely proportional to the total pressure and can be related to the liquid Reynolds number. 

The manometric method can only be used for polyatomic molecules under favourable circumstances, such as obtain in the dissociation N2O4 —> 2NO2, studied by several workers. The equilibrium pressure results were combined with an experimental... 

The possibility that reactions other than recombination will be entered into by dissociation products is the main objection to the static manometric method. In the effusion method this possibility is diminished by the use of low temperatures and pressures. In the flow method the dissociation equilibrium is established in a flow system so that although a static concentration of reactants and products is set up, the product molecules do not remain sufficiently long in the reaction vessel for side reactions to take place. The time of contact or time which the gas stream takes to traverse the reaction vessel is adjusted so that the molecules are in the vessel long enough for equilibrium to be established, and, it is hoped, for a short enough time for the main advantage of the method to be obtained. The concentration of the dissociation products is usually determined spectroscopically. 

This method is in effect a variation on the manometric method, using a very special technique for measuring the pressure of molecules. 

Early steady state kinetic studies established techniques for monitoring the overall reaction and for determining substrate specificity. The most generally applicable method for determining steady state rates of the oxidases is O2 consumption. Oxygen electrode techniques (28) have now superseded earlier manometric methods. The enzyme preparations must either be completely free of catalase activity, as a result of high enzyme purity or addition of cyanide, or catalase must be added in amounts sufficient to prevent transient H2O2 accumulation. 

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