Dumas method

The two chief methods for estimating nitrogen in organic compounds are (i) the Dumas method, which can be applied to all organic compounds (ii) the Kjeldahl method, which is of more restricted application, but which is frequently used in biochemical and physiological work. Its limitations are indicated in the description of the method (p. 492). 

The 5-nitrofurfurylidene hydrazide of 4-hydroxybenzoic acid obtained was washed with water and methanol end was dried at a moderate temperature. It weighed 23 g (83.7% yield), and melted at 298°C. The percentage nitrogen determined by the micro-Dumas method was 15.41% (theory 15.27%). 

A universal procedure for combined nitrogen is the Dumas method. This gasometric procedure is applicable to any organic compd contg nitrogen in any form, such as amino, nitroso, nitro, azo, cyano, nitrate, nitrite, as well as N in heterocyclic compds. The procedure involves combusting the sample in a closed system in a C02 atm, with subsequent reduction of the oxides... 

Note The N detn was made by the Dumas method as modified byP. Jovinet and S. Courte-cuisse [MemServChimEtat 32, 16 (1945) and Etat Francais, FrP 510911 (1946)], because other methods, such as the nitrometer Or the Kjeldahl, did not give reliable results... 

TABLE FOR CALCULATIONS IN THE DETERMINATION OF NITROGEN BY DUMAS METHOD... 

A recent brief review showed the working principles of various automatic analyzers6. A modified account of N and O analysis will be presented here. Today there exist in the market instruments that perform organic elemental analyses in a few minutes. The ease and speed of such analyses enable the use of such instruments for routine analysis. Although some operational details vary from model to model and between one manufacturer and another, all these instruments can be considered as exalted versions of the classical Pregl determination of C and H by conversion to CO2 and H2O, together with Dumas method for N by conversion to N2, the calorimetric bomb method for S by conversion to SO2 and SO3 and Schultzes method for O by conversion to CO. This is combined with modern electronic control, effective catalysts and instrumental measuring methods such as IR detectors and GC analyzers. 

Total nitrogen determinations in barley and malt gave slightly higher results by the Dumas than by the Kjeldahl method. The Dumas method was adopted as the reference method by the Analysis Committee of the Institute of Brewing27. Comparison of the results obtained by the Kjeldahl method with those of automatic N analyzers is mentioned in Section III.A.2 above. 

The determination of nitrogen in petroleum products is performed regularly by the Kjeldahl method (ASTM D3228), the Dumas method, and the microcoulomet-ric (ASTM D3431) method. The chemiluminescence method is the most recent technique applied to nibogen analysis for petroleum and is used to determine the amount of chemically bound nitrogen in liquid samples. 

Dumas method analychem A procedure for the determination of nitrogen in organic substances by combustion of the substance. dti-ma. meth-od dunnite See ammonium picrate. da.nTt)... 

A. Smith and R. H. Lombard have pointed out that most of the methods of determining vapour densities—e.g. Y. Meyer s method, J. B. A. Dumas method— are useful in detecting qualitatively the existence of dissociation, but do not show the extent of dissociation when the vapours are sat. since the vapour densities of the unsaturated vapours are alone measured, and the system therefore behaves as if under reduced press., a condition which favours dissociation. A. Smith and R. H. Lombard s measurements of the vapour densities of sat. ammonium chloride, enable the extent of the dissociation to be calculated at different temp. Let D0... 

The first synthesis of an organic fluoride was devised by the French chemists, Dumas and Peligot.10 During a detailed study of the chemistry of methanol (wood spirit), dimethyl sulfate and anhydrous potassium fluoride were heated together in a glass vessel. Fluoromethane was formed, and characterized, its vapor density being determined (presumably by Dumas method). 

Carbon disulphide vapour appears to be associated to a small extent. When the vapour and ether vapour are mixed at constant volume at 80° C. under atmospheric pressure, the increase of pressure observed indicates previous association of the carbon disulphide to the extent of 0-14 per cent., whilst vapour density determinations by Dumas method give results corresponding with 2 per cent, association.3... 

All analyses by Dumas method except when marked (K) for Kjeldahl. 6 2.5-mg sample. c No data. 

Alternate Protocol 1 Nitrogen Determination Using the Dumas Method B1.2.3... 

Drop volume tensiometer (DVT), for interfacial tension, 636-638 DSA. see Drop shape analysis Dumas method, nitrogen content... 

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