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The determination of manganese in the presence of iron and chromium by differential pulse voltammetry and fundamental harmonic alternating current voltammetry was compared, including the case of very high element concentration ratios. The voltammetric measurements were carried out using a stationary mercury electrode in ammonia-ammonium chloride buffer (pH 9.6). The analytical procedure was verified...
The complex formation between Mn(II) cations and N -3 anions was studied in aqueous medium at 25 o C and ionic strength 2.0 M (NaClO 4 ). Data of average ligand number, n (Bjerrum's function), were obtained from pH measurements on the Mn(II)/N -3 /HN 3 system followed by integration to obtain Leden's function, F 0 (L). Graphical treatment...
The potentiometric determination of the protonation constant of 2-chlorophenol in NaCl media at different ionic strengths and its distribution coefficient between these media and two organic solvents at 25 o C are presented. An automated potentiometric system was used, and the determination of the constants was carried out using both graphical and numerical methods. A thermodynamic model...
A new polymeric chromogenic reagent PA.FPNS has been synthesized by condensing polyallylamine (PA) with 3-(4-formylphenylazo)-4,5-dihydroxynaphthalene-2,7-disulfonic acid (FPNS) and its properties studied. In alkaline media, PA.FPNS reacts with magnesium to form a water-soluble blue complex, whose absorption maximum is at 604 nm. The molar absorptivity ( ) of the complex is 5.2 x 10 4 1...
The distribution behavior of ion associates of PtCl 2-6 with quaternary ammonium cations (Q + ) between aqueous phase and two organic phases (chloroform and carbon tetrachloride) was examined, and the extraction constants (log K ex ) were determined. A linear relationship was found between log K ex and the total number of carbon atoms in Q +...
A novel flow sensor based on chemiluminescence (CL) for the determination of ascorbic acid has been proposed. The analytical reagents, luminol and ferricyanide, were both immobilized on an anion-exchange resin column. The CL signal produced by the reaction between luminol and ferricyanide, which were eluted from the column through sodium phosphate injection, was decreased in the presence of ascorbic...
The potentiometric and impedance characteristics of polymeric membranes, based on aliphatic polyurethane (Tecoflex) as a matrix, are described and interpreted by theory and experiments for H + and alkali metal ion-sensitive sensors. Both dummy plasticized membranes and proton carrier-loaded membranes can show pH response. The pH response of dummy membranes is due to protonated natural negative...
The stability constants of the fluoride complexes of cerium(IV) in 1 M (HClO 4 , NaClO 4 ) medium have been measured potentiometrically using a fluoride ion-selective electrode. Quantitative oxidation of cerium to its tetravalent state and its stabilisation in the perchlorate medium were accomplished by oxidation with AgO followed by quick addition of a known amount of fluoride ion...
Sodium di-n-propyldithiophosphinate has been proposed as a reagent to improve the sorption properties of activated carbon. The conditions for sorption concentration and separation of bismuth from aqueous solutions were studied. Possibilities for desorption and subsequent determination of bismuth by atomic emission spectroscopy with inductively-coupled plasma were shown.
A d.c. polarographic technique has been used previously for the determination of the pesticide, ziram, in aqueous samples. this paper reports differential pulse anodic stripping voltammetric determination of ziram zinc in rice samples using a static mercury drop electrode. The procedure developed distinguishes inorganic zinc and ziram zinc in sodium acetate-sodium chloride media. The procedure...
A porous polytetrafluoroethylene (PTFE) junction reference electrode with an air-tight inner solution chamber containing saturated potassium chloride (KCl) was developed for flow analysis. This reference electrode is not influenced by a change in the sample pressure, and is not necessary to supply the KCl inner solution. The pore size of the porous PTFE junction is about 150 μm, although the conventional...
Methods for the direct determination of silver in sea water samples by ETA-AAS using different chemical modifiers were studied. The effect of salinity was studied using synthetic sea water of high (72.8%%) and low (34.2%%) salinity, and the results were compared with aqueous standard solutions. The charring temperatures achieved were 800 and 900 o C for magnesium nitrate and ammonium dihydrogen...
In recent years, the use of chlorine dioxide as an alternative disinfectant for drinking water has become increasingly attractive. As a result, an accurate method for the determination of mg l -1 concentrations of chlorine dioxide is needed. Improvements to chlorophenol red (CPR) spectrophotometry result in a selective method for ClO 2 with few interferences. CPR selectively...
Chemically modified electrodes based on zeolite-containing graphite pastes were constructed and evaluated as sensor electrodes for the voltammetric determination of traces of metallic species in solution. Zeolite molecular sieves with pore sizes of 3, 4, 5, and 10 a were all suitable for chemical deposition and subsequent voltammetric quantitation of traces of Cu(II), Cd(II), and Zn(II). The highest...
An ammonia sensor is described in this work. The sensing membrane is a thin layer of oxidized polypyrrole (PPy) on a platinum substrate. This sensor is used as the working electrode in a conventional three-electrode system for amperometric measurement of ammonia in aqueous solutions in the potential range of +0.2 to +0.4 V (vs. Ag/AgCl). Contact with ammonia causes a current to flow through the...
The interactions of Bromophenol Blue (BPB) with bovine serum albumin and γ-globulin in acidic solutions were investigated by a spectrophotometric method. It was considered that the electrostatic force is the main binding force, and that the color change during the combination is due to the transformation of dye species of free acidic form into bound basic form as well as to the bathochromic and hyperchromic...
Formation of Cu(II) and Ni(II) complexes of 1,2,-dihydroxy-9,10-anthraquinone (DHA) has been studied by the spectrophotometric method. Both the metals form stable complexes of the type [M(LH) 3 ] - where LHH 1 represents DHA. The effective stability constant of the Cu(II) complex is 5.135 x 10 29 while that of the Ni(II) complex is 3.446 x 10 25 ...
A flow injection analysis system incorporating amperometric detection and enzyme reactor for glycerol determination in alcoholic beverages is described. The reactor is based on the glycerol dehydrogenase system, and the enzyme was immobilized through chemical modification on several supporting materials such as aminopropyl and isothiocyanate controlled pore glass, aminopolystyrene resin and m-aminobenzyloxymethyl...
A method for the determination of total chromium in cocaine and heroin by flameless atomic absorption spectrometry is presented. Cocaine samples were dissolved in 2 ml of HNO 3 35.0% (v/v) and diluted to 10 ml with ultrapure water; heroin samples were dissolved in ultrapure water, adding 0.4 ml of HNO 3 35.0% (v/v) to dissolve inert species, and also diluted to 10 ml. Mg(NO 3...
Regenerated silk fibroin prepared from waste silk was employed as immobilization matrix for peroxidase and the structures of the blend membranes of regenerated silk fibroin and peroxidase were first investigated with IR and scanning electron microscopy. There was intermolecular interaction between peroxidase and regenerated silk fibroin in the immiscible state. Cyclic voltammetry and constant applied...
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