Kjeldahl-nitrogen

SCWO Supercritical Water Oxidation TKN Total Kjeldahl Nitrogen TOC Total Organic Carbon TSS Total Suspended Solids WAO Wet Air Oxidation... 

Griepink B, Gonska H, Muntau H (1983) The Certification of the Contents (Mass Fractions) of Nitrogen, Phosphorus, Chloride, Sodium, Potassium, Magnesium and Calcium and of the Kjeldahl-Nitrogen Content of a Skim Milk Powder, BCR No. 63. Report EUR 9138 EN. Commission of the European Communities, Brussels. 

As microwave sample preparation has evolved, standard microwave procedures have been developed and approved by numerous standard methods organisations (ASTM, AOAC International, EPA, etc.), see ref. [64]. Examples are standard test methods for carbon black/ash content (ASTM Method D 1506-97), lead analysis in direct paint samples (ASTM Method E 1645-94), etc. Table 8.15 shows some microwave ashing references (detection weight). A French AFNOR method utilises the atmospheric pressure single-mode microwave method as an alternative sample preparation procedure for Kjeldahl nitrogen determination [84], The performance of a microwave-assisted decomposition for rapid determination of glass fibre content in plastics for QC has been described [85]. 

Association Franjaise de Normalisation, Kjeldahl Nitrogen Determination with Microwave Sample Preparation, Rept NF V03-100 (1992). 

COD, chemical oxygen demand TKN, total Kjeldahl nitrogen TSS, total suspended solids VSS, volatile suspended solids TOC, total organic carbon. 

The quantity of protein present is normally measured by the Kjeldahl method. As wheat endosperm protein is around 17.5% nitrogen a factor of 5.7 is normally used to convert Kjeldahl nitrogen measurements into protein. Tkachuk suggested that 5.7 should be used for whole wheat but 5.6 should be used for flour.24... 

The value to be used for the protein content is defined as the Kjeldahl nitrogen multiplied by 6.25. Similarly, there are definitions regarding saturated fatty acids. 

Kjeldahl digestion, 22 88 Kjeldahl nitrogen determinations, for paper, 18 99... 

Possible hazards introduced by variations in experimental techniques in Kjeldahl nitrogen determination were discussed [1]. Modem variations involving use of improved catalysts and hydrogen peroxide to increase reaction rates, and of automated methods, have considerably improved safety aspects [2], An anecdote is given of the classic technique when sodium hydroxide was to be added to the sulphuric acid digestion and was allowed to trickle down the wall of the flask. It layered over the sulphuric acid. Gentle mixing then provoked rapid reaction and a steam explosion [3],... 

The whole column, apart from a small portion of the sediment, is sam pled in this way. The chemical checks were carried out every 15 days, determining pH, Conductivity, C.O.D., Ammoniacal Nitrogen, Orthophosphate Phosphorus and, furthermore, each month Total phosphorus, Total Kjeldahl Nitrogen, Total Solids and Volatile Solids. The methods utilized are those indicated in the Standard Methods (A.P.H.A., 1980). The amount of matter particles sedimented in the tanks was estimated with the use ol appropriate sampling devices located at the bottom of the tanks and withdrawn after a variable permanence of 40 to 60 days. 

The following characteristics were analysed by standard methods (9) TS, volatile solids (VS), chemical oxygen demand (COD), Kjeldahl nitrogen (Kj-N) and ammoniacal nitrogen (NH3-N). The biochemical oxygen demand of whole slurry (BODw) was analysed by a dilution method (10). Volatile fatty acids (VFA) were analysed by gas... 

Attached-growth waste stabilization ponds have been used to remove 65-70% TKN (total Kjeldahl nitrogen), and 70-83% NH3-N from concentrated latex and rubber sheet plant wastewaters [8]. A combined algae and water hyacinth system has been used to remove 96.41% COD, 98.93% TKN, 99.28% NH3-N, 100% NO2-N, and 100% NO3-N [9]. 

Unavailable N Acid detergent Kjeldahl nitrogen on ADF residue Maillard products plus lignified N... 

Levels of metabolites other than carbohydrates were also altered in roots of Ponderosa pine seedlings as a result of chronic ozone exposure (Tingey and Wilhour, unpublished). After three months of exposure, which coincided with the appearance of visual injury, amino acid levels in roots of exposed seedlings were elevated above those of the controls (Fig. 8A). The amino acid levels remained above that of the control for the remainder of the season. Also the levels of Kjeldahl nitrogen were higher in roots of exposed than of control plants throughout the season (Fig. 8B). 

Figure 8. Ozone alteration of amino acid and Kjeldahl nitrogen levels in the roots of Ponderosa pine seedlings exposed to chronic ozone doses. Each mean is based on nine observations.

Potassium sulfate is used in fertilizers as a source of potassium and sulfur, both of which are essential elements for plant growth. Either in simple form or as a double salt with magnesium sulfate, potassium sulfate is one of the most widely consumed potassium salts in agricultural apphcations. It is preferred over potassium chloride for certain types of crops such as, tobacco, citrus, and other chloride—sensitive crops. Some other applications include making gypsum cements to make potassium alum in the analysis of Kjeldahl nitrogen and in medicine. 

In the Kjeldahl nitrogen determination (Reactions 7-3 through 7-5), the final product is a solution of NHJ ions in HCI solution. It is necessary to titrate the HCI without titrating the NH ions. 

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