Nitrate spectrophotometric analysis

Spectrophotometric Analysis of the Lanthanides in Molten Nitrate Media, W.T. Camall, Anal. Chem. 34, 786-791 (1962). 

Phenol-di-sulphonic acid was used for the spectrophotometric analysis of nitrate. Model U 2000 Spectrophotometer of Hitachi make was used at 470 nm (maximum absorbance). 

Box 6-1 stated that nitrogen compounds derived from animals and plants are broken down to ammonia hetm>trophic bacteria. Ammonia is oxidized first to nitrite 02 ) and then to nitrate (NO J) by nitrifying bacteria. In Section 6-3 we saw how a permanganate titration was used to standardize a nitrite stock solution. The nitrite solution is used here to pr xue standards for a spectrophotometric analysis of nitrite in aquarium water. 

Spectrophotometric analysis. This method of analysis requires the addition of ferric nitrate and mercuric thiocyanate to the irradiated ethanol-monochlorobenzene solution (Razem et al. 1981). The radiolytically generated CP ions react with the mercury(II) thiocyanate followed by the reaction of the liberated thiocyanate ions with ferric ions to produce the red colored ferric thiocyanate complex, which is measured at 485 nm. The method is applicable in the dose range of 10-10 Gy. 

The carboxylic acid groups were converted first to the potassium salt and then to Co(II) salts by addition of cobalt(II) acetate solution to the copolymer latex with agitation in an ultrasonic bath to produce the latex catalysts listed in Table 1. The latexes were purified by ultrafiltration through a 0.1 im cellulose acetate/nitrate membrane (Millipore) until tiie conductivity of the filtrate at 25 C was constant at 40 x lO" ohm l cm"l. Purified latexes contained 1-2% solids. An upper limit of 3 x 10" for the firaction of Co(II) not bound to the latex was established by addition of 1,10-phenanthroline to the ultrafiltrate and UV-visible spectrophotometric analysis of tiie Co(II) complex. By the same criterion, addition of 6 mol of pyridine per mol of Co(II) to form the active catalysts did not extract cobalt ions from the latex. Thus practically dl of the Co(II) was bound to latex. A typical transmission electron micrograph of catalyst RC-1 is shown in Figure 1. 

Absorption spectrophotometric analysis procedures have been developed for a number of environmental species. For water contaminants alone, these include procedures for the determination of arsenic, boron, bromide ion, cyanide, fluoride, nitrate, phenols, phosphate, selenium, sUica, sulfide, surfactants, and tannin and lignin. A typical such procedure is the spectrophotometric determination of phenol in water by the reaction with 4-aminoantipyrene... 

Spectrophotometric methods for determining concentration of Pu(111, IV, VI, and "polymer") in nitrate media have been reported.(30) Adaptation of such procedures to routine rapid in-line analysis of feed and raffinate solutions may be possible. 

Erk and Altun [24] used a ratio spectra derivative spectrophotometric method and a high performance liquid chromatographic method for the analysis of miconazole nitrate and metronidazole in ovules. The spectral method depends on ratio spectra first derivative spectrophotometry, by utilizing the linear relationship between substances concentration and ratio spectra first derivative peak amplitude. The ratio... 

Analytical Methods. Temperature, pH, and oxygen were measured in situ by using a combined sensor (Ztillig). Ammonium was determined by flow injection analysis (27), and nitrate and silicate by spectrophotometric methods (Auto-Analyzer) (28). Sulfide was determined by using a H2S-specific electrode (29). 

The products of the thermolysis of 3-phenyl-5-(arylamino)-l,2,4-oxadiazoles and thiazoles have been accounted for by a radical mechanism.266 Flash vacuum pyrolysis of 1,3-dithiolane-1-oxides has led to thiocarbonyl compounds, but the transformation is not general.267 hi an ongoing study of silacyclobutane pyrolysis, CASSF(4,4), MR-CI and CASSCF(4,4)+MP2 calculations using the 3-21G and 6-31G basis sets have modelled the reaction between silenes and ethylene, suggesting a cyclic transition state from which silacyclobutane or a trcins-biradical are formed.268 An AMI study of the thermolysis of 1,3,3-trinitroazacyclobutane and its derivatives has identified gem-dinitro C—N bond homolysis as the initial reaction.269 Similar AMI analysis has determined the activation energy of die formation of NCh from methyl nitrate.270 Thermal decomposition of nitromethane in a shock tube (1050-1400 K, 0.2-40 atm) was studied spectrophotometrically, allowing determination of rate constants.271... 

Garcia Gutierrez [19] has described an azo coupling spectrophotometric method for the determination of nitrite and nitrate in soils. Nitrite is determined spectrophotometrically at 550 nm after treatment with sulfuric acid and N-1 -naphlhylclhylcnediamine to form an azo dye. In another portion of the sample, nitrate is reduced to nitrite by passing a pH 9.6 buffered solution through a cadmium reductor and proceeding as above. Soils were boiled with water and calcium carbonate, treated with freshly precipitated aluminium hydroxide and active carbon, and filtered prior to analysis by the above procedure. 

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. 

The potential advantages of selective nitration of tyrosyl residues in native proteins are numerous. The reaction is performed under mild conditions, giving rise to a 3-nitrotyrosyl derivative (pK 7), which in the acid form absorbs intensely at 350 nm. Hence, the nitrotyrosine content may be readily determined spectrophotometrically, as well as by amino acid analysis ( 2.2.3). The absorption spectrum of 3-nitro-tyrosine is highly sensitive to solvent polarity and exhibits significant optical activity in the long wavelength absorption band. Consequently, nitrotyrosyl residues can be utilized as indicators of conformational change, or of interactions of proteins with other macromolecules or small molecules (e.g. Kirschner and Schachman 1973). Any perturbation in the pK of nitrotyrosyl residues is readily determined spectrophotometrically. 

ISO/TR 11905-2). Another method oxidizes nitrogen forms into nitrates which can be then estimated (NF EN ISO 11905-1). Lastly, an ISO/CD 29441 method, under development, uses UV digestion, followed by flow injection analysis (FIA), continuous flow analysis (CFA) with spectrophotometric detection, and allows automation of the method. 

M.F. Gine, B.F. Reis, E.A.G. Zagatto, F.J. Krug, A.O. Jacintho, A simple procedure for standard additions in flow injection analysis. Spectrophotometric determination of nitrate in plant extracts, Anal. Chim. Acta 155 (1983) 131. 

An alternative sampling approach is to deploy a submersible analyser [14,15]. Water is sucked from the exterior environment by an on-board pump in order to fill the sampling loop, with excess sample directed back to the exterior. The flow system is remotely controlled and the results can be either stored in the analyser or transmitted back to the ship via a cable. In this context, a small submersible flow injection analyser, with solid-state spectrophotometric detection, was conceived for the in situ determination of nitrate (Fig. 8.2). Its performance and versatility were assessed by results from laboratory, shipboard (North Sea IMPACT Cruise) and in situ (Tamar Estuary, UK) analysis. Excellent temporal and spatial resolutions were reported and this aspect is crucial for investigating dynamic processes in estuarine, coastal and open ocean waters. 

The spectrophotometric determination of Fe(II), Fe(III), nitrate and nitrite ions in natural and wastewaters in a sequential injection system [298] is an interesting example of this innovation. In-line tangential filtration was performed prior to the sample insertion port as part of the sampling step. Particulate material was not aspirated towards the holding coil and several samples could be analysed without the need for frequent cleaning of the filtration unit. Analytical figures of merit were similar to those for the corresponding flow-based analytical procedure with manual sample filtration prior to flow analysis. 

Ensafi, A. A., Rezaei, B. and Nouroozi, S. (2004) Simultaneous spectrophotometric determination of nitrite and nitrate by flow injection analysis. Anal Sci, 20 (12), 1749-1753. 

Once in solution, the preferred method for measurement of boron is inductively coupled plasma atomic emission spectroscopy (ICP-AES) or inductively coupled plasma mass spectrometry (ICP-MS). The most widely used nonspectrophotometric method for analysis of boron is probably ICP-MS because it uses a small volume of sample, is fast, and can detect boron concentrations down to 0.15 pgL . When expensive ICP equipment is not available, colorimetric or spectrophotometric methods can be used. However, these methods are often subject to interference (e.g., nitrate, chloride, fluoride), and thus must be used with caution. Azomethine-H has been used to determine boron in environmental samples (Lopez et al. 1993), especially water samples. Another simple, sensitive spectrophotometric method uses Alizarin Red S (Garcia-Campana et al. 1992). 

L. Andersson, Simultaneous Spectrophotometric Determination of Nitrite and Nitrate by Flow Injection Analysis. AnaL Chim. Acta, 110 (1979) 123. 

S. Xu and Z. Fang, Sinultaneous Spectrophotometric Determination of Nitrate and Nitrite in Water and Soil Extracts by Flow Injection Analysis [in Chinese]. Fenxi Huaxue, 11 (1983) 93. 

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