Nitrogen, total, determination

Oxygen is present only in small quantities in petroleum as illustrated in Table 1.5, and its concentration is usually determined by subtracting the combined carbon, hydrogen, and nitrogen total from 100. 

The principle underlying surface area measurements is simple physisorb an inert gas such as argon or nitrogen and determine how many molecules are needed to form a complete monolayer. As, for example, the N2 molecule occupies 0.162 nm at 77 K, the total surface area follows directly. Although this sounds straightforward, in practice molecules may adsorb beyond the monolayer to form multilayers. In addition, the molecules may condense in small pores. In fact, the narrower the pores, the easier N2 will condense in them. This phenomenon of capillary pore condensation, as described by the Kelvin equation, can be used to determine the types of pores and their size distribution inside a system. But first we need to know more about adsorption isotherms of physisorbed species. Thus, we will derive the isotherm of Brunauer Emmett and Teller, usually called BET isotherm. 

Combustion methods have been used to determine total sulphur and total organic carbon and total halides in soil, total and particulate organic carbon, total halide, phosphorus and nitrogen, total and particulate organic carbon in saline sediments and total nitrogen in sludges. 

Solyom [37] has carried out intercalibration studies on methods for the determination of total nitrogen in sludges. Nitrogen was determined by oxidation in alkaline solution with potassium peroxydisulphate, followed... 

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in the tanks was estimated with the use ol appropriate sampling devices located at the bottom of the tanks and withdrawn after a variable permanence of 40 to 60 days. 

Total and nitrate nitrogen were determined by Kjeldahl and colorimetric methods, respectively (29,30). Organic matter was determined by the wet oxidation method of Walkley (31). Soil pH was determined with a glass electrode in a 2 1 mixture of water and soil. 

Total nitrogen was determined using standard mlcrokjeldahl digestion, and terpenes were analyzed using a Perkin Elmer 3920 gas chromatograph equipped with a Perkin Elmer 0.10 In x 150 ft capillary column packed with 85% OS-138, 14% CO-880, and 1%... 

Total nitrogen is determined by chemical digestion (Kjeldahl-Gunning) methods. 

Crude protein and total lysine plus furosine Total nitrogen was determined by macro Kjeldahl digestion and protein estimated as N x 6.25. Total lysine values were obtained from conventional amino acid analyses carried out on 500-mg samples following digestion with 800 ml of 6M HC1 under reflux by use of a Biotronic LC 6000 or Kontron Liquimat III amino acid analyzer. Furosine was determined in the same way using 300 ml 7.8 M HC1 as described in ( 6 ) with an amino acid analyzer ( 7 ). 

Attempts were made to prove the existence of the particulate amines by other techniques with only limited success. At best, indirect evidence (7) was obtained from the fact that nitrate and ammonium cannot account for total particulate nitrogen as determined by combustion. However, the observed nitrogen deficiency was much less than indicated by ESCA. An attempt to detect Nx by infrared spectroscopy (8) failed because of interfering absorption bands. 

We have used the ESCA results to provide empirical information about the apparent stoichiometry of sulfate, ammonium, and nitrate ions and other elements and species. Wet chemical analyses performed at several laboratories seemed to contradict some of the conclusions reached from ESCA studies. For example, total reduced nitrogen as determined by ESCA often agrees with the determination of ammonium by wet chemical methods. A consequence of this discrepancy is that in analyses where wet analysis would indicate ammonium sulfate, ESCA would suggest ammonium bisulfate, based on the assumption that particulate Nx species are not associated with sulfate. This assumption may not be valid, because it has been demonstrated QJ that a large fraction of Nx present... 

Total nitrogen was determined in water using high-temperature oxidation and chemiluminescence,119 as well as microwave digestion-UV spectrophotometry.120 Total nitrogen in solid waste was determined by modified Kjeldahl-Nessler reagent colorimetrically and modified Kjeldahl titration with hydrochloric acid.121 No significant differences were found between the two methods in terms of accuracy and precision. 

Zink-Nielsen, I. 1977. Intercalibration of methods for chemical analysis of sediments results from intercalibrations of methods for determining loss on ignition, COD, total nitrogen, total phosphorus, and heavy metals in sediments. Vatten 33 14—20. 

Analysis. The heating value, ash content, and sulfur distribution of the raw and treated coals were determined according to ASTM procedures (7). Iron in the extracts of the raw and treated coals was determined by titration with a cerium (IV) solution. Iron in the residues from the acid extractions of the raw and treated coals was determined spectrophotometrically using ferrozine (20). The liquid extracts were analyzed for total sulfur (as sulfate) by ion chromatography after separation of the sulfate from nitrate on an alumina column (21). Nitrogen was determined in the raw and treated coal and in their nitric acid-extracted residues by a modified Kjeldahl method. 

Lead Determine as directed for Method I in the Atomic Absorption Spectrophotometric Graphite Furnace Method under Lead Limit Test, Appendix IBB, using a 5-g sample. Protein (Total) Determine as directed under Nitrogen Determination, Appendix IIIC. The protein content is N x 6.25. 

Total a-amino nitrogen is determined by its reaction with o-phthaldialdehyde. The intensity of the absorbance 340 nm is compared to that obtained for standards of known concentrations of isoleucine. 

In all experiments reported here ozone was determined by the alkaline-potassium iodide method of Smith and Diamond (13) as modified by Byers, Saltzman, and Hyslop (2). The total oxides of nitrogen were determined by the phenoldisulfonic acid method nitrogen dioxide by the specific method of Saltzman (11). The accuracy of the ozone method is still under experimental scrutiny. It is possible that some factorial upward revision of the ozone values reported here may have to be made at a future date. A correction factor of approximately 2 appears probable at this date. The method, however, was the best available at the time these experiments were performed. 

Laboratories, Inc., Wheat Ridge, Colorado. Total nitrogen was determined using the Dumas method. Total organic oxygen content was determined by difference based on ash-free samples. 

From the Chapter Resources menu, choose Web Works. Locate the Chapter 16 section, and click on the link to the executive summary of the Lake Champlain Basin Agricultural Watersheds Project. The report summarizes a project to improve water quality in Lake Champlain in Vermont and New York. Based on your reading of the report, what appears to be the primary general cause of the eutrophication of Lake Champlain What types of industry are the sources of the pollution What measures have been taken to reduce the pollution Briefly describe the experimental design to determine whether these measures have been effective. Total Kjeldahl nitrogen (TPCN) determinations were one of the quantities measured in this study name three others. Explain how TKN provides a measure of pollution in the lake. Based on the TKN measurements and other data in the report, have the pollution abatement measures been effective What are the final recommendations of the report ... 

Total sulfur in gas can be determined by combustion (ASTM D-1072), by the lamp method (ASTM D-1266), or by hydrogenation (ASTM D-3031, ASTM D-4468). Trace total organic and bound nitrogen is determined (ASTM D-4629). The current test method for heavy residues in liquefied petroleum gas (ASTM D-2158) involves evaporation of a liquefied petroleum gas sample, measuring the volume of residue and observing the residue for oil stain on a piece of filter paper. 

No adverse effect on liver weight was observed in female ICR mice treated by gavage with 400 mg/kg petroleum creosote in DMSO on gestational days 5-9 (Iyer et al. 1993). In a feed study of MGP coal tar by Weyand et al. (1994), B6C3Fj mice were exposed to 0, 51, 251, or 462 mg/kg/day (males) and 0, 42, 196, or 344 mg/kg/day (females) in the feed for 94 or 185 days. Plasma clinical chemistry parameters determined were as follows glucose, creatine, blood urea nitrogen, total protein, ALT, ALT, and alkaline phosphatase activity. Tissues obtained from the animals were examined for microscopic lesions. There was no adverse effect of treatment on liver histopathology or serum enzymes. 

The acid phase was divided into several portions that were used to make the following measurements. The total acidity (reported as percent sulfuric acid) was determined by titration with a standard sodium hydroxide solution using a methyl purple indicator. Total sulfuric acid was determined in a second sample in a similar manner after the nitric acid and lower oxides of nitrogen were expelled by evaporation on a steam bath. Lower oxides of nitrogen were determined by a redox method. Total nitric acid was determined by difference. 

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