Analysis ammonia content

Widespread medicinal use of colloidal bismuth subcitrate (CBS) has prompted extensive studies of bismuth compounds involving the citrate anion. Bismuth citrate is essentially insoluble in water, but a dramatic increase in solubility with increasing pH has been exploited as a bio-ready source of soluble bismuth, a material referred to as CBS. Formulation of these solutions is complicated by the variability of the bismuth anion stoichiometry, the presence of potassium and/ or ammonium cations, the susceptibility of bismuth to oxygenation to Bi=0, and the incorporation of water in isolated solids. Consequently, a variety of formulas are classified in the literature as CBS. Solids isolated from various, often ill-defined combinations of bismuth citrate, citric acid, potassium hydroxide, or ammonium hydroxide have been assigned formulas on the basis of elemental analysis data or by determination of water and ammonia content, but are of low significance in the absence of complementary data other than thermal analysis (163), infrared spectroscopy (163), or NMR spectroscopy (164). In this context, the Merck index lists the chemical formula of CBS as KgfNHJaBieOafOHMCeHsCbh in the 11th edition (165), but in the most recent edition provides a less precise name, tripotassium dicitrato bismuthate (166). 

The water and ammonia content of anhydrous N2Hj are determined by a gas chromatography (Refs 37 38) method, and the analysis of the aniline in the mixture by ultraviolet spectroscopy. The total N2Hj content can be then determined by difference. Other methods are given at the end of section on Hydrazine Chemistry... 

The concentration of copper in the solution should be followed by a rapid, approximate colorimetric procedure until it reaches approximately 17 g. copper per liter. At this point the solution is decanted into a tightly stoppered bottle and stored in the refrigerator pending accurate analyses for copper and ammonia. It will usually be necessary to build up the ammonia content by the introduction of ammonia gas at this point, and a second analysis is often required before final adjustment to the desired concentrations can be made. 

The ammonia content was measured using a standard procedure with absorption in sulphnric acid solution (1 M) and subsequent analysis using ion selective electrodes (Orion EA 920 Ion analyser). The sampling time used for ammonia was approximately 15 minutes and the mean values from the gas analysis and the bed temperature was always calculated for the same period. 

An analysis of out going gases should be carried out. They should contain 35—40% NjO and 25—30% NHj. The end of the reaction is manifested by the fall in the ammonia content to 3—5% NH3 and the fall of temperature. The time to carry out the reaction of one batch is ca, 30 hours and the yield is 28—30 kg. The content of the reactor is cooled to 100°C and washed with water. Care should be taken with this process, as water reacts vigorously (exothermic reaction) with unreacted sodamide. Sodium azide with sodium hydroxide is taken by water (200 1), filtered and evaporated to a density of 1.55-1.57 at 20 C, Sodium azide is collected, washed with a small quantity of water and finally with ethanol. 

The ammonia content of freshly drawn blood rises rapidly on standing because of the deamination of labile amides such as glutamine (Henry 1964). At room temperature, the ammonia content can increase by a factor of two or three in several hours. Therefore, it is important to keep the specimen cold and perform the analysis as soon as possible. Alternatively, the sample should be frozen. The ammonia content of iced samples remains constant for 30-60 minutes for samples collected from a healthy person, but should be analyzed within 15 minutes in a patient suspected of suffering from liver disease (Huizenga et al. 1994). The ammonia content of iced samples remains constant for 20 minutes the ammonia... 

The determination of ammonia content in gas samples by vapor phase chromatographic analysis for nitrogen after catalytic decomposition was described by Diedrich et al. A Dynatronics chrom-Analyzer model 100 gas chromatograph equipped with thermal conductivity detector was... 

A number of simple, standard methods have been developed for the analysis of ammonium compounds, several of which have been adapted to automated or instmmental methods. Ammonium content is most easily deterrnined by adding excess sodium hydroxide to a solution of the salt. Liberated ammonia is then distilled into standard sulfuric acid and the excess acid titrated. Other methods include colorimetry (2) and the use of a specific ion electrode (3). 

Equations (141) and (142) describe the equilibrium between the hydrolysis of complex fluoride acids (shift to the right) and the fluorination of hydroxides (shift to the left). Near complete precipitation of hydroxides can be achieved by applying an excessive amount of ammonia. Typically, precipitation is performed by adding ammonia solution up to pH = 8-9. However, the precipitate that separates from the mother solution can be contaminated with as much as 20% wt. fluorine [490]. Analysis of niobium hydroxides obtained under different precipitation conditions showed that the most important parameter affecting the fluorine content of the resultant hydroxide is the amount of ammonia added [490]. Sheka et al. [491] found that increasing the pH to 9.6 toward the end of the precipitation process leads to a significant reduction in fluorine content of the niobium hydroxide. 

Titration is a general word used in many different disciplines. Any time a solution of known concentration is used to find the amount of an unknown component in another solution, it can be called a titration. Although this type of analysis is very old, it still finds widespread used in chemical analysis. Titrations are used in soil analysis to measure soil acidity, soil organic matter content, and various constituents isolated from soil, particularly ammonia. 

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 )... 

The first enzyme that was demonstrated to contain nickel was urease (urea amidohydrolase) from jack bean. It catalyzes the hydrolysis of urea to ammonia and carbon dioxide. The protein has a multimeric structure with a relative molecular mass of 590,000 Da. Analysis indicated 12 nickel atoms/mol. Binding studies with the inhibitors indicated an equivalent weight per active site of 105,000, corresponding to 2 nickel atoms/active site. During removal of the metal by treatment with EDTA at pH 3.7, the optical absorption and enzymatic activity correlated with nickel content. This, combined with the sensitivity of the enzyme to the chelating agents acetohydroxamic acid and phos-phoramidate, indicates that nickel is essential to the activity of the enzyme (1). 

Regression analysis in time series analysis is a very useful technique if an explanatory variable is available. Explanatory variables may be any variables with a deterministic relationship to the time series. VAN STRATEN and KOUWENHOVEN [1991] describe the dependence of dissolved oxygen on solar radiation, photosynthesis, and the respiration rate of a lake and make predictions about the oxygen concentration. STOCK [1981] uses the temperature, biological oxygen demand, and the ammonia concentration to describe the oxygen content in the river Rhine. A trend analysis of ozone data was demonstrated by TIAO et al. [1986]. 

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