Gasometric Method for Determination

Gasometric Method for Determination of Ammonium Nitrate Content by Means of Nitrometer A373 to A377... 

Collins [7] has described a gasometric method for the determination of carbonate in soil based on reaction with hydrochloric acid and subsequent measurement of the volume of carbon dioxide produced. This is also the basis of a standard HMSO method for the determination of carbonate in soils [8] (Fig. 6.2). 

Figure 6.2. Gasometric method for the determination of carbonate in soil. From [7]...

Protein Content. The protein content of milk can be determined using a variety of methods including gasometric, Kjeldahl, titration, colorimetric, and optical procedures (see Proteins). Because most of the techniques are too cumbersome for routine use in a dairy plant, payment for milk has seldom been made on the basis of its protein content. Dye-binding tests have been appHed to milk for determination of its protein content these are relatively simple to perform and can be carried out in dairy plant laboratories. More emphasis will be given to assessing the nutritional value of milk, and the dependence on fat content as a basis for payment will most likely change. 

Gasometric methods have long been practiced because of their simplicity and accuracy. For a long time however, these methods have been performed only on a macro or semimicro scale. (A remarkable fact van Leeuwenhoek tried to measure blood gas on a true ultramicro scale in 1692 see Letter No. 72.) Manometric methods are preferred instead of volumetric methods because of their greater accuracy. A volumetric instrument for gasometry on ultramicro scale (samples of 20 [xl) nevertheless was developed by Lazarow (LI, L2) and according to the author, the reproducibility for CO2 determination in serum is better than 1 vol % (L3). 

Gas Content Measurements. The generally accepted standard procedure to determine 02 and C02 in blood is the Van Slyke gasometric technique (18). This apparatus was modified by Roughton and Scho-lander (19) for use with blood samples in the microliter range. The principal drawbacks to the gasometric method center on the many steps required to complete an analysis. They are time-consuming, tedious procedures, needing a skilled operator to achieve optimum accuracy (20). 

The discussion of the methods for measuring the oxidation of donor substances has shown the great variety of possible techniques. Only two titration methods and hve gasometric peroxidase assays seem to have been published for the determination of the residual substrate. 

The possibility of oxidation by a mixed mechanism, including both direct electrochemical oxidation and dehydrogenation, is not excluded. Daniel -Bek and co-workers [173, 174] proposed a method for combining gasometric and polarization determination in order to determine the proportions of each mechanism in the overall process. Such a division is based on the assumption that the dehydrogenation rate does not depend on potential, whereas the electrochemical oxidation rate bears an exponential relationship to cp [see, however, Eqs. (16) and (20) and the experimental results cited below]. 

There is a variety of analytical methods used for ceruloplasmin determinations the most frequently used is the p-phenylenediamine oxidase method, by virtue of its high precision. The oxidation rate of p-phenylenediamine or a derivative is measured spectrophotometrically or gasometrically, determining ceruloplasmin oxidase activity. Sunderman and Nomoto (132) determined plasma ceruloplasmin by measuring... 

For the determination of BOD, respiratory methods based on the principles of gasometric analyses have also been used [14, 23-29]. By means of respirometers the whole course of BOD and respiratory rates of sludges... 

The appearance of the amino group can be measured by its reaction with nitrous acid, reaction with ninhydrin (colorimetrically or gasometrically), titration in acetone, and titration in the presence of formaldehyde. The appearance of a carboxyl group can be measured by titration in ethanol. Specific methods can be used for the determination of certain amino acids when these are liberated by hydrolysis. 

By analogy, the anion exchangers like Amberlite IR-4 should bind preferentially the dicarboxylic acids. This is also the case. A mixture of amino acids and hydrochloric acid, which is stirred for 1 to 3 hours with sufficient resin IR-4 to give a final pH of 6 to 7, will adsorb completely the acidic amino acids and leave the neutral and basic amino acids unaffected (Cannan 1944, Cleaver et al., 1945). On the pure fraction eluted with HCl from the resin, Cannan determined the aspartic and glutamic acids separately by a combination of electrometric titrations in water and formaldehyde solutions and a gasometric ninhydrin estimation—a method well suited for work on a semi-micro scale. 

In a method described >for the determination of lower alkyl and hydride groups in organoaluminium compounds, a known weight of sample is reacted at a low temperature with 2-ethyl hexanol in a specially constructed nitrogen or helium gasometric system, (Figure 41). 

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