Ammonia Kjeldahl analysis

A steam distillation apparatus is shown on the right-hand side of Figure 10.7. This same apparatus can be used to determine ammonia in soil as described previously. A flow diagram for the determination of ammonia in soil using a Kjeldahl analysis is given in Figure 10.8 [6],... 

These concentrations are determined by volumetric ammonia uptake measurements, Kjeldahl analysis and titrimetrical Cl analysis. The trichlorosilylation occurred at standard conditions and the ammoniation was performed for 5 h in excess ammonia. 

In papers dedicated to side reactions to nitration, no attention has been paid to the formation of ammonia in the course of the reaction. It is formed from hydrogen cyanide produced by drastic decomposition of nitro compounds. This was discussed in detail in Vol. I, pp. 76—77. The mechanism of the formation of HCN from C-nitro compounds also explains the fact that these nitro compounds yield ammonia in Kjeldahl analysis, where the substance is subjected to the action of oleum at high temperature. 

Kjeldahl method analychem Quantitative analysis of organic compounds to determine nitrogen content by interaction with concentrated sulfuric acid ammonia Is distilled from the Nff4S04 formed. kel,dal, meth-ad )... 

Ammonium Dichromate, Analytical Procedures. Accdg to Taylor and Rickenbach(See Ref lb), above, the methods of its analysis are identical with those of K dichromate, except that the total ammonia should be detd by the Kjeldahl method. See also under Ammonium Chromate and US Federal Specification OA-498a Barium Dlchromate, BaCr20 , mw 353.38 red, monocl crysts mp ( ) sol in hot coned H2S04 decompd by w. Can be prepd by action of a soln of chromic acid on freshly pptd Ba... 

The method was checked by analysis according to Kjeldahl (reduction of the fixed nitrogen to ammonia) and by analysis of measured amounts of nitric oxide let into the cylinder from a pipette. 

The TAPPI64 methods are satisfactory for analysis of cuprammonium alternatively, electrolytic depositions methods may be employed for the copper66 and Kjeldahl techniques for the ammonia. 

ProMera 10.11 A Kjeldahl nitrogen analysis of a 3.88-mg sample of etlumolamine required 5.73 ml of 0.0110 N hydrochloric acid for titration of the ammonia produced. Calculate the percentage of nitrogen in the compound. 

Paper is an important filtering medium. Ashless paper is manufactured from cellulose fibers that have been treated with hydrochloric and hydrofluoric acids to remove metallic impurities and silica ammonia is then used to neutralize the acids. The residual ammonium salts in many filter papers may be sufficient to affect the analysis for nitrogen by the Kjeldahl method (see Section 37C-11). 

The Kjeldahl method for the determination of nitrogen is the one generally used in the analysis of food-products and other complex mixtures. The substance to be analyzed is heated with concentrated sulphuric acid until it is completely oxidized. The nitrogen present is converted into ammonia, which unites with the excess of sulphuric acid to form ammonium sulphate. The amount of ammonia formed is determined by treating the mixture of the acid and ammonium salt with an excess of sodium... 

Proteins in foods can be measured by NIR reflectance spectrometry with no sample preparation. This has replaced the standard Kjeldahl protein nitrogen determination, which required extensive sample preparation to convert protein nitrogen to ammonia, distillation of the released ammonia, and subsequent titration of the ammonia. The replacement of the Kjeldahl method for routine analysis by NIR has permitted online measurement of protein in food and beverage products. The Kjeldahl method is required for assaying the materials used to calibrate the NIR and for method validation. 

Munich,[B] and applied to the analysis of nitro- explosives by M. Chenel, of the Laboratoire Centrale des Poudres, whose method of proeedure is as follows —0.5 gmi. of the finely powdered substance is digested in the cold with a solution of 1.2 gim. of phenol and 0.4 grm. phosphoric anhydride in 30 c.c. of sulphuric acid. The mixture is kept well shaken until the solution is complete. From 3 to 4 grms. of zinc-dust is then cautiously and gradually added, the temperature of the mass being kept down until complete reduction has been effected. Finally, 0.7 grm. of mercury is added, and the process continued in the usual way, according to Kjeldahl that is, the hquid is distilled until all the ammonia has passed over, and is absorbed in the standard acid. The distillate is then titrated with standard ammonia. 

The quantitative elemental analysis of organic compounds, perfected by Liebig for carbon and hydrogen in 1831 and by Dumas for nitrogen in 1834, has been described in Chapter 8. An alternative method for the determination of nitrogen was devised in 1883 by Johan Kjeldahl (1849-1900) in which the element is converted to ammonia, which is then determined by titration. The standard... 

A Kjeldahl analyzer is used to determine ammonia (by a digestionless method), or total organic nitrogen by acid digestion followed by steam distillation and potentiometric titration. This unit performs all steps automatically and calculates the %N in the sample. The technique is suitable for liquids and powders that can be catalytically converted to ammonium ion. This method is complementary to the combustion method, which is much faster and has become the method of choice for analysis of nitrogen content. 

The Kjeldahl method was adapted to the analysis of PN in the range of 5—50 mg N [53]. In this case, the glass microfiber filters used to collect the particulate (0.5-1 L of filtered sample) were placed in the test tube and digested with the acid reagent mixture. The resulting ammonia was determined colorimetrically at 570 nm, after formation of the complex with ninhydrin-hydrindantin reagent. 

The determination of ammonia after the regular or modified Kjeldahl digestion presents rather less serious problems than those already dis cussed. The advantages of the micro-Kjeldahl distillation (69, 80, 81, 82, 83) as compared with the macro>method, or even the semimicro-method are now generally recognized. A comparative study of the macro-and microscale determination in the analysis of flour, wheat and com for their protein content was made by Robinson and Shellenberger (27). The micro-Kjeldahl method has been used for systematic plasma protein analysis (84, 85), saliva proteins (86), milk proteins (87), and cerebrospinal fluid protein (88),... 

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