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A simple and rapid preconcentration technique, based on collecting trace nitrite on a membrane filter and dissolving the membrane filter in an organic solvent, has been applied to its spectrophotometric determination in water. At pH 2.0, nitrous acid diazotizes with p-aminoacetophenone, which is then coupled with N-(1-naphthyl)-ethylenediamine, at the same pH. The azo dye formed is collected on a...
A flow-injection manifold is proposed for determination of nitrite based on the reaction with 3,6-diamino acridine (proflavin sulfate) in hydrochloride acid medium. The assembly is adapted for nitrate determination by including a reductive column filled with copperized cadmium. The influence of foreign substances is also studied. The method gives a linear calibration graph over the range 0 06-4mg...
A highly sensitive and selective procedure is presented for the voltammetric determination of cobalt. The procedure involves an adsorptive accumulation of cobalt-2,2 -bipyridine complex on a hanging mercury drop electrode, followed by a stripping voltammetric measurement of the catalytic reduction current of nitrite at - 1.25 V (vs. Ag/AgCl). The optimum conditions for the analysis of cobalt include...
The lack of reference materials, accurately certified for nitrite, is a problem in view of the importance of this species for environmental and medical reasons. This work outlines a plan for the preparation of nitrite isotopic reference materials (IRMs) in the form of high purity solutions, certified for their nitrite–nitrogen isotopic composition and nitrite concentration. To achieve the desired...
A novel thin-layer amperometric detector (TLAD) based on chemically modified ring-disc electrode and its application for simultaneous measurements of nitric oxide (NO) and nitrite (NO2−) in rat brain were demonstrated in this work. The ring-disc electrode was simultaneously sensitive to nitric oxide (NO) and nitrite (NO2−) by modifying its inner disc with electropolymerized film of cobalt(II) tetraaminophthalocyanine...
A flow injection catalytic spectrophotometric method is proposed for the determination of nitrite based on its catalytic effect on the redox reaction between naphthol green B and potassium bromate in phosphoric acid medium. The reaction is monitored spectrophotometrically by measuring the decrease in absorbance of naphthol green B at the maximum absorption wavelength of 722 nm. The detection limit...
The construction of a wall-jet cell with amperometric detection using a set of disc electrodes whose radii ranged from 5 to 750 μm has been proposed. The influence of some experimental parameters like flow rate and electrode radius on hydrodynamic voltammograms recorded for a 0.5 mmol dm -3 potassium ferrocyanide solution also containing 0.1 mol dm -3 KCl has been discussed...
A series of generic nitrite assay systems based on the single step nitrosation of phenol derivatives are presented. The chemical reactivity offered by the C-nitroso compounds provides an opportunity to pursue a number of analytical strategies of which three spectroscopic (UV/Vis) and two electrochemical options (linear sweep voltammetry/differential pulse voltammetry) were evaluated. The capacity...
A method for spectrophotometric determination of nitrite and nitrate is described. This method is based on the reduction of phosphomolybdic acid to phosphomolybdenum blue complex by sodium sulfide. The obtained phosphomolybdenum blue complex is oxidized by the addition of nitrite and this causes a reduction in intensity of the blue color. The absolute decrease in the absorbance of the blue color or...
(C 70 ) 2 -p-tert-butylcalix[6]arene complex films on GC electrode surface showed two couples of redox reactions in mixed solvent of (1:1, v:v) acetonitrile and water containing tetra-butylammonium perchlorate. The electrocatalytic reduction for nitrite by these films was observed, indicating that (C 70 ) 2 -p-tert-butylcalix[6]arene is capable of mediating...
A review of the strategies employed to facilitate the detection, determination and monitoring of nitrate and/or nitrite is presented. A concise survey of the literature covering 180 reports submitted over the past decade has been compiled and the relevant analytical parameters (methodology, matrix, detection limits, range, etc.) tabulated. The various advantages/disadvantages and limitations of the...
Normal phase ion-pair high performance liquid chromatography has been used for simultaneous separation of nitrite and nitrate using tetraethylammonium (TEA) + as ion-pairing reagent. The concentration effect of (TEA) + , buffer salt and pH of the eluent on separation is investigated. The UV detector response at various wavelengths has been optimized. The performance of the proposed...
A flow injection method on the basis of gas phase molecular absorption is described for the determination of nitrite in the aqueous solution. 200 μl of nitrite solution is introduced into a carrier stream of distilled water. The carrier stream containing nitrite zone is reacted with a stream of hydrochloric acid (2 M). The stream is then segmented by O 2 gas. The produced gaseous products...
A new sequential injection analysis (SIA) method of an electrokinetic flow analysis (EKFA) system for the determination of nitrite-nitrogen is presented in this paper. The proposed system mainly consisted of an electroosmotic pump, two solenoid valves and a spectrophotometer etc. All the pump and valves were controlled by a personal computer automatically. The determination method of nitrite-nitrogen...
A direct spectrophotometric flow injection method for the simultaneous determination of nitrite and nitrate has been developed. The method is based on the oxidation of a phosphomolybdenum blue complex by the addition of nitrite and the decrease in absorbance of the blue complex is monitored at 820 nm. The injected sample is split into two segments. One of the streams was directly reacted with the...
Capillary electrophoresis (CE) is used to quantify nitrate and nitrite extracted from nitrite-impregnated glass fiber filters (IGFF) that are used to monitor ozone in atmospheres. The amount of nitrate produced from conversion of nitrite in the filters is directly related to the amount of ozone passed over the filter. The limit of detection for ozone using the CE method is 1.17 ppml and the method...
A new synthesized fluorescent probe, 1,3,5,7-tetramethyl-8-(3',4'-diaminophenyl)-difluoroboradiaza-s-indacence (TMDABODIPY), has been used to detect nitrite. When TMDABODIPY reacted with nitrite, a weak fluorescent triazole formed in 0.2 mol l -1 HCl medium at room temperature. The fluorescence quenching intensity was linear over a nitrite concentration of 0.04-0.32 μmol l -1...
A new flow injection catalytic spectrophotometric method is proposed for the simultaneous determination of nitrite and nitrate based on the catalytic effect of nitrite on the redox reaction between crystal violet and potassium bromate in phosphoric acid medium and nitrate being on-line reduced to nitrite with a cadmium-coated zinc reduction column. The redox reaction is monitored spectrophotometrically...
A simple, sensitive and selective fluorimetric method for the determination of nitrite ion in waters using a merging zones flow injection system is described. The fluorimetric determination is based on the measurement of the quenching effect produced by nitrite on proflavine (3,6-diaminoacridine) fluorescence (λ ex /λ em =290/519nm).The optimum experimental conditions were...
A highly sensitive and virtually specific method has been developed for the trace and ultra trace 5ngml -1 -1μgml -1 fluorimetric analysis of nitrite. The method is based on the quenching action of nitrite on the native fluorescence of murexide (ammonium purpurate) [λ ex =349.0nm, λ em =444.5nm] in the acid range of 0.045-0.315 (M) H 2 SO...
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