共查询到20条相似文献,搜索用时 31 毫秒
1.
2-(4-Toluenesulphonamido)aniline,TSA, was examined to evaluate the claim that it is a specific gravimetric reagent for copper(II) and to see if the application of the reagent could be extended. The nature of the reaction and complexes was investigated by potentiometry, solvent extraction, spectrophotometry, polarography and mass spectrometry. A 1:2 copper: TSA complex formed at pH 6 (K1=1019.11 in 50% (v/v) aqueous dioxane) is suitable for the gravimetric determination, as previously reported. A violet complex (λmax. 550 nm, ε=6620) of uncertain composition is formed at pH 10–11 and may be used for the spectrophotometric determination of copper. The centres of chelation have been deduced from the infrared spectra of the complex and reagent and the causes of the selectivity are discussed. 相似文献
2.
An extraction-spectrophotometric method is described for the determination of traces of iron(II) with 2-[2-(3,5-dibromopyridyl)azo]-5-diethyl-aminobenzoic acid. The reagent forms a stable and blue 12 iron/reagent complex that can be extracted into chloroform. The apparent molar absorptivity of the iron(II) complex is 1.09 × 105 1 mol–1 cm–1 at 624 nm in chloroform. The reagent is relatively selective; interferences from cobalt, copper, nickel and vanadium can be removed by using dimethylglyoxime and EDTA. The method is applied to the determination of iron (II) in sea water and aluminium alloys with good precision and accuracy. 相似文献
3.
Takeo Katami Tomokuni Hayakawa Masamichi Furukawa Shozo Shibata Tadashi Hara 《Analytica chimica acta》1986
An extraction-spectrophotometric method is described for the determination of traces of zinc with 2-[2-(3,5-dibromopyridyl)azo]-5-dimethylaminobenzoic acid. The reagent forms a stable, blue 1:2 zinc/reagent complex that can be extracted into chloroform. The apparent molar absorptivity of the zinc(II) complex is 1.26 × 105 l mol?1 cm?1 at 610 nm in chloroform. The reagent is relatively selective; interferences from cobalt, copper and nickel can be masked with dimethylglyoxime and aluminium and iron with a mixture of sodium fluoride and triethanolamine. The method is applied to the determination of zinc in coal fly ash and pond sediments with good precision and accuracy. 相似文献
4.
Permanganate is determined spectrophotometrically at 545 nm after extraction into chloroform of the ion-associate, ethylene -bis (triphenylphosphonium) permanganate. The carrier stream is pH 6 buffer containing 10% (w/v) ammonium fluoride and the reagent stream is 0.25% (w/v) ethylene-bis (triphenylphosphonium) bromide. The injection rate is 24 h?1. Th calibration graph is linear up to 25 μg ml?1 and the detection limit is 0.58 μg m?1 Mn (VII), based on 250- μl injections. The system is applied to the determination of manganese in a range of steels. 相似文献
5.
A procedure is described for the preconcentration of Cd(I), Co(II), Cr(III), Cu(II), Mn(II), U(VI) and Zn(II) from 800 ml of water and sea-water samples by coprecipitation with 1-(2-pyridylazo)-2-naphthol (PAN) prior to neutron activation. Chromium is reduced to Cr(III) by hydroxylammonium chloride at pH 4 before the preconcentration step. Coprecipitation of 30 mg of PAN was most effective at pH 9 with final recoveries of 76–91% for six elements and 50% for uranium. The scheme is based on double irradiation of the same samples. Short (10 min) irradiation followed by γ-spectrometry counting for 10 min gives data for Cd (111mCd), Co, Cu, Mn and U (239U). A second 16-h irradiation permits determination of zinc and uranium (239Np) after a waiting time of 6 h, cadmium (115Cd) after 24 h and chromium after a waiting period of 2 weeks followed by counting for 30 min. Detection limits are 0.04 ng g?1 for Co, 0.8 ng g?1 for Cd, 0.3 ng g?1 for Cu, 0.2 ng g?1 for Cr, 0.006 ng g?1 for Mn, 0.006 ng g?1 for U and 0.3 ng g?1 for Zn. A further decrease of the detection limit for chromium to 0.05 ng g?1 can be achieved by separation of interfering nuclides and scintillation counting of 51Cr with a NaI(Tl) well-type detector. 相似文献
6.
Two chelating reagents, disodium N,N′-dibenzylethylenebisdithiocarbamate 1 and disodium piperazinebisdithiocarbamate 2, were synthesized and used to preconcentrate trace metals in aqueous samples. For analysis of Cu(II) using a UV-vis spectrometer, Beer's law was obeyed from 5.0 μg L?1 to 6.0 mg L?1 for reagent 1, and from 0.2 mg L?1 to 6.0mg L?1 for reagent. 2. The chelation ratio for reagent 1 to Cu(II) was determined to be 1:1, with a formation constant 1.0 × 109 M?l. The dependence of extraction and extraction efficiency of reagent 1 on pH was also studied with an atomic absorption spectrometer for nine heavy-metal ions-Cu(II), Fe(III), Pb(II), Co(II), Cr(VI), Ni(II), Zn(II), Mn(II) and Cd(II). Except Cr(VI) and Mn(II), the recovery yields of the other seven metal ions were almost quantitative at pH = 4 ? 6. The recovery was 82% for Cr(VI) at pH = 4 ? 5, and 52% for Mn(II) at pH = 6 ? 7. 相似文献
7.
Preparation and Characterization of Chromium of Chromium(V)- and Manganese(V)- nitridophthalocyanines(1-) and -(2-): [MNPc(1-)]+ and [MNPc(2-)] (M=Cr, Mn) Nitridophthalocyaninatochromium(V), [CrNPc(2-)], is prepared by oxidation of [Cr(OH)2PC(2-)] with chlorine in the presence of excess ammonia as a paramagnetic (μeff = 1,99 B.M.), Microcrystalline blue powder. Through chemically very stable it reacts as well as the isostructural nitridophthalocyaninatomanganese(V) with bromine or concentrated nitric acid giving ring- oxidized darkblue nitridophthalocyaninatomental(poly)bromides or -nitrates, [MNPc(1-)]X (M=Cr, Mn; X=Bry, NO3; y≈?2). The nitrido-metal stretching vibration (ν(N?M)) is independent of the oxidation state of the Pc-ligands at ca. 1017 cm?1 for the chromium and at ca. 1055 cm?1 for the manganesenitridophthalocyanines. ν(N?Mn) is resonance Raman (r.r.) enhanced, ν(N?Cr) not. The characteristic differences in the u.v. -vis., f.i.r./m.i.r. and r.r. spectra of [MNPc(2-)] and [MNPc(1-)+ and the influence of aggregation of phthalocyanine-radicals are discussed. 相似文献
8.
Ca(II) ions react with arsenazo, 2-(4-arsonophenyl)-azo-7-(4-antipyril)azo-l,8-dihydroxy-3,5-naphtalene disulphonic acid, at pH 10.0 to produce a blue complex, with stoichiometry 11, and stability constant of 6.64×105. Its molar absorptivity is 3.78×1041·mol–1 cm–1. This reagent has been used as metallochromic indicator in the complexometric titration of Ca. Its colour transition has been specified by tristimulus colourimetry. New parameters are defined and compared to Ringbom's parameters. 相似文献
9.
《Analytical letters》2012,45(9):1737-1748
Abstract Isonitroso-4-methyl-2-pentanone (HIMP) is proposed as a new reagent for extraction and photometric determination of Pd(II). The reagent forms a yellow complex with palladium in the pH range 4.0-5.0. The complex extracted into chloroform was measured at 330 nm. The molar absorptivity was found to be 5.37 × 103 1 mol?1 cm?1 and Sandell's sensitivity 20 ng cm?2 Beer's law was obeyed over the concentration range 0.1-10.0 μg/ml of palladium. The method is applicable for palladium estimation in Ores and catalysts. 相似文献
10.
Martina Lešková Yaroslav R. Bazel Marcel Torok Yaroslav Studenyak 《Chemical Papers》2013,67(4):415-422
The structure of styryl dye, 2-[(E)-2-(4-dipropylaminophenyl)-1-ethenyl]-1,3,3-trimethyl-3H-indolium chloride (I), was investigated using methods such as UV-VIS, fluorescence spectroscopy, and NMR (1H, 13C, APT, HMQC, COSY) and also by examining its electrochemical properties. A study of the acid-base properties revealed the existence of three different forms of the dye. The mechanisms of protolysis and hydrolysis are discussed. The reagent exists in a reactive single-charged form I + over a wide range of acidity (pH 4–11). The optimum analytical wavelength of the singlecharged form is 550 nm, where the molar absorptivity is 5.51 × 104 L mol?1 cm?1. The values of the optimum analytical wavelength and molar absorptivity of the protolysed and hydrolysed forms are: λ max(I-H2+) = 380 nm, ?(I-H2+) = 2.01 × 104 L mol?1 cm?1; λ max(I-OH) = 320 nm, ?(I-OH) = 1.12 × 104 L mol?1 cm?1. A theoretical study of the spectral and chemical properties of I was carried out by performing quantum chemical calculations. 相似文献
11.
《Analytical letters》2012,45(1-2):99-112
Abstract A spectrophotometric study of the Pd(II) complex of a reagent 2-(5-Bromo-2-Pyridylazo)-5-(diethylamino)-Phenol (5-Br-PADAP) is presented. A violet complex is formed at pH 3.53, and shows maximal absorbance at 585 nm with molar absorptivity of 3.86 × 104 1. mol?1 cm?1. Beer's law is obeyed up to 50 μ of Pd(II). The method offers the advantages of simplicity, high precision, requires no extraction and is very selective, where 5.0 mg Pt(VI) and 0.3 mg Au(III) ions do not interfere. 相似文献
12.
Stability constants of copper(II) complexes formed by 2-(2′-carboxymethyl-thiophenylazo)-5-nitrotoluene in dioxane—water solvent mixtures of several different compositions [50, 60 and 75% dioxane (v/v)] were determined from EMF measurements, at 25°C and 0.1 mol dm?3 NAClO4 ionic medium. Graphical treatment of experimental data gives for the equilibria nA?+Cu2+ = CuAn(2-n)+ (n = 1 or 2), in a solvent with X% (v/v) dioxane, the following values of log β1, and log β2 (given here successively). X = 50:2.41, 6.77; X = 60:3.36, 7.45; X = 75:4.33, 7.64. The relation between solvent composition and the values found for the stability constants is discussed. From EMF measurements made with the copper(II) ion-selective electrode, at constant pH, the nature of the effective donor groups in this potentially terdentate ligand is inferred. 相似文献
13.
C. Zucchi M. Forneris L. Martínez R. Olsina E. Marchevsky 《Fresenius' Journal of Analytical Chemistry》1998,360(1):128-130
A selective and precise spectrophotometric determination of vanadium(V) is performed after preceding extraction with N-benzoyl-N-phenylhydroxylamine
(BPHA). The color is developed in a water-ethanol solution with hydrogen peroxide and 2-(5-chloro-2-pyridylazo)-5-dimethylaminophenol
(5-Cl-DMPAP). The molar absorptivity at 588 nm is (6.57 ± 0.05) × 104 L mol–1 cm–1 at pH 2.1. The method permits the determination of vanadium (V) at trace levels in the presence of large amounts of other
ions. It is applied to the determination of vanadium in aluminium (analytical reagent grade) and in human hair. High accuracy
and precision is obtained.
Received: 18 April 1997 / Revised: 20 June 1997 / Accepted: 25 June 1997 相似文献
14.
A new spectrophotometric method for the determination of gallium is described using 1-(2,4-dihydroxyphenylazo) -2-naphthol-4-sulfonic acid (DHPAN) as a reagent. The color reaction has a sensitivity of 0.013 μg Ga per cm2 for log 10/1=0.005 at 500 mμ and obeys Beer's law up to 2.8 p.p.m. The effects of pH, time, order of addition of the reagents, temperature and diverse ions were investigated. Gallium is separated from interfering ions by solvent extraction. 相似文献
15.
《Analytical letters》2012,45(11):2455-2471
Abstract A method is proposed for the simultaneous determination of nickel and manganese by first-derivative spectrophotometry based on their reactions with 2-(2-pyridylmethyleneamino)phenol (PMAP) Schiff base. The method allows the determination of Ni and Mn in the concentration range 0.3–3.0 μg ml?1 in mixtures with their ten-fold concentration ratio. The method has been applied for Ni and Mn determination in bronzes. To optimize the experimental conditions for spectrophotometric determination of Mn with PMAP stability constants at different pH values have been determined. A critical evaluation of the proposed method was performed by statistical analysis of the experimental data. 相似文献
16.
Arafa A. M. Belal 《Transition Metal Chemistry》1995,20(4):384-387
Summary A spectrophotometric method for determining trace amounts of CuII using 4-(
-nitro-phenyl)azo-2-phenyloxazolin-5-one has been devised. With this reagent, CuII forms a stable chelate, in the 6–9.5 pH range which obeys Beer's law at 555 nm with a molar absorptivity of 4.50 × 103 mol–1 cm2. Other copper-group metals do not interfere with this process. The stoichiometry and stability constant of the copper chelate has been determined using spectrophotometric, potentiometric and conductometric methods. 相似文献
17.
The use of 2-(6-methyl-2-benzothiazolylazo)-5-diethylaminophenolas a precolumn derivatizing reagent in the reversed-phase high performance liquid Chromatographic separation and determination of Ru(III), Rh(III), Os(IV), Ir(IV), Pt(II), Co(II), Ni(II) and Cu(II) is reported. When the mobile phase consists of methanol-water (76/24% v/v) and 20 mmol/l (pH 5.0) acetate buffer, the eight complexes can be separated within 35 min on a C8 column. The detection limits are Ru 7.0, Rh 5.1, Os 1.5, Ir 7.6, Pt 3.7, Co 0.62, Ni 0.14 and Cu 1.2 ng/ml, respectively, at a signal-to-noise ratio of 3. RSDs were typically Ca. 1%. 相似文献
18.
《Polyhedron》1986,5(7):1253-1257
Complex formation between Ni(II), Co(II) and Mn(II) and 3-(2-furyl)-2-mercaptopropenoic and 3-(2-furyl)-2-mercaptopropanoic acids has been studied using glass electrode potentiometry. Ligand-metal ion mixtures in 10% (v/v) ethanol-water containing 0.1 mol dm–3KNO3 were titrated with potassium hydroxide. The e.m.f. data obtained have been analyzed using the linearization method, and initial estimates of protonation constants for the ligands and complex formation constants have been refined with the MINIQUAD program. 相似文献
19.
A rapid method has been described for the quantitative extraction of milligram amounts of Mn/II/ with 2-PRONAPOX into CHCl3. The extraction coefficient /E/ of Mn/II/ between CHCl3 and aqueous solution containing 0.2M NH4Cl shows a maximum value of E=143 at pH 10.5. The percentage extraction is better than 98% in the pH range from 9 to 11 and an equilibration time of 6 min. The effects of anions and cations have been studied. The stoichiometry of metal: reagent determined by substoichiometric extraction and slope ratio method is found to be 12. The decontamination factors for most of the elements are better than 104 in the substoichiometric extraction of Mn/II/. 相似文献
20.
C. Zucchi M. Forneris L. Martínez R. Olsina E. Marchevsky 《Analytical and bioanalytical chemistry》1998,360(1):128-130
A selective and precise spectrophotometric determination of vanadium(V) is performed after preceding extraction with N-benzoyl-N-phenylhydroxylamine (BPHA). The color is developed in a water-ethanol solution with hydrogen peroxide and 2-(5-chloro-2-pyridylazo)-5-dimethylaminophenol (5-Cl-DMPAP). The molar absorptivity at 588 nm is (6.57 ± 0.05) × 104 L mol–1 cm–1 at pH 2.1. The method permits the determination of vanadium (V) at trace levels in the presence of large amounts of other ions. It is applied to the determination of vanadium in aluminium (analytical reagent grade) and in human hair. High accuracy and precision is obtained. 相似文献