scholarly journals Boric Acid Modification of the Kjeldahl Method for Crop and Soil Analysis

1920 ◽  
Vol 12 (4) ◽  
pp. 350-352 ◽  
Author(s):  
F. M. Scales ◽  
A. P. Harrison
Keyword(s):  
Boric Acid ◽  
Soil Analysis ◽  
Acid Modification ◽  
Kjeldahl Method

Determination of nitrogen in soil by the Kjeldahl method

1960 ◽  
Vol 55 (1) ◽  
pp. 11-33 ◽  
Author(s):  
J. M. Bremner
Keyword(s):  
Sulphuric Acid ◽  
Salt Concentration ◽  
Soil Analysis ◽  
Sodium Sulphate ◽  
Soil Conditions ◽  
Organic Soils ◽  
Ammonium N ◽  
Kjeldahl Digestion ◽  
Kjeldahl Method

1. The reliability of the Kjeldahl method for the determination of nitrogen in soils has been investigated using a range of soils containing from 0·03 to 2·7% nitrogen.2. The same result was obtained when soil was analysed by a variety of Kjeldahl procedures which included methods known to recover various forms of nitrogen not determined by Kjeldahl procedures commonly employed for soil analysis. From this and other evidence presented it is concluded that very little, if any, of the nitrogen in the soils examined was in the form of highly refractory nitrogen compounds or of compounds containing N—N or N—O linkages.3. Results by the method of determining nitrogen in soils recommended by the Association of Official Agricultural Chemists were 10–37% lower than those obtained by other methods tested. Satisfactory results were obtained by this method when the period of digestion recommended was increased.4. Ammonium-N fixed by clay minerals is determined by the Kjeldahl method.5. Selenium and mercury are considerably more effective than copper for catalysis of Kjeldahl digestion of soil. Conditions leading to loss of nitrogen using selenium are defined, and difficulties encountered using mercury are discussed.6. The most important factor in Kjeldahl analysis is the temperature of digestion with sulphuric acid, which is controlled largely by the amount of potassium (or sodium) sulphate used for digestion.7. The period of digestion required for Kjeldahl analysis of soil depends on the concentration of potassium sulphate in the digest. When the concentration is low (e.g. 0·3 g./ml. sulphuric acid) it is necessary to digest for several hours; when it is high (e.g. 1·0 g./ml. sulphuric acid) short periods of digestion are adequate. Catalysts greatly affect the rate of digestion when the salt concentration is low, but have little effect when the salt concentration is high.8. Nitrogen is lost during Kjeldahl analysis when the temperature of digestion exceeds about 400° C.9. Determinations of the amounts of sulphuric acid consumed by various mineral and organic soils during Kjeldahl digestion showed that there is little risk of loss of nitrogen under the conditions usually employed for Kjeldahl digestion of soil. Acid consumption values for various soil constituents are given, from which the amounts of sulphuric acid likely to be consumed during Kjeldahl digestion of different types of soil can be calculated.10. Semi-micro Kjeldahl methods of determining soil nitrogen gave the same results as macro-Kjeldahl methods.11. The use of the Hoskins apparatus for the determination of ammonium is described.12. It is concluded that the Kjeldahl method is satisfactory for the determination of nitrogen in soils provided a few simple precautions are observed. The merits and defects of different Kjeldahl procedures are discussed.

Revised Kjeldahl Total Nitrogen Method for Feeds and Premixes

1972 ◽  
Vol 55 (5) ◽  
pp. 984-985
Author(s):  
Robert Odland
Keyword(s):  
Boric Acid ◽  
Refractory Material ◽  
Total Nitrogen ◽  
Crude Protein ◽  
Analysis Time ◽  
Acid Method ◽  
Kjeldahl Method ◽  
Complete Digestion

Abstract A Kjeldahl method for equivalent crude protein in feeds was modified by using a smaller sample (0.25 g) and smaller amounts of reagents in order to reduce analysis time and cut costs. A 6% CuSO4 catalyst was used for the complete digestion of refractory material. Winkler’s boric acid method was modified by including a 90% pretitration to insure complete retention of ammonia so that only one standardized reagent is needed.

To study the effect of boric acid modification on starch–polyvinyl alcohol blend wood adhesive

2018 ◽  
Vol 15 (2) ◽  
pp. 190-198 ◽  
Author(s):  
Ravindra V. Gadhave ◽  
Pratik Sanjiv Kasbe ◽  
Prakash A. Mahanwar ◽  
Pradeep T. Gadekar
Keyword(s):  
Polyvinyl Alcohol ◽  
Boric Acid ◽  
Wood Adhesive ◽  
Acid Modification

A note on the determination of soil organic matter: A wet combustion method

1929 ◽  
Vol 19 (4) ◽  
pp. 727-733 ◽  
Author(s):  
F. Hardy
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Organic Carbon ◽  
Chromic Acid ◽  
Soil Analysis ◽  
Combustion Method ◽  
Kjeldahl Method

(1) A gasometric method for the determination of organic carbon in soils by the use of sulphuric-chromic acid mixtures at 100° C., as suggested by Watts in 1902, is described, and recommended for use in routine soil analysis.(2) The method is compared with the Kjeldahl procedure recently introduced by Robinson, McLean and Williams, and is found to give results which are generally similar, though numerically slightly lower.(3) The wet combustion method is somewhat simpler than the Kjeldahl method, but it has the disadvantage that nitrogen determinations cannot be made simultaneously, so that its usefulness in studies on soil organic matter is decidedly less.

Improved visible-light photoactivity of Pt/g-C3N4 nanosheets for solar fuel production via pretreated boric acid modification

2018 ◽  
Vol 45 (2) ◽  
pp. 249-259 ◽  
Author(s):  
Yuying Wang ◽  
Linlu Bai ◽  
Ziqing Zhang ◽  
Yang Qu ◽  
Liqiang Jing
Keyword(s):  
Visible Light ◽  
Boric Acid ◽  
Solar Fuel ◽  
Fuel Production ◽  
Acid Modification
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