2-(4-Toluenesulphonamido)aniline as an analytical reagent : The nature of the reaction with copper(II)

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=10^19.11 in 50% (v/v) aqueous dioxane) is suitable for the gravimetric determination, as previously reported. A violet complex (λ_max. 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.     

Extraction-spectrophotometric determination of trace iron (II) in sea water with 2-[2-(3,5-dibromopyridyl)azo]-5-diethylaminobenzoic acid

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.     

Extraction and spectrophotometric determination of zinc in coal fly ash and pond sediments with 2-[2-(3,5-dibromopyridyl)azo]-5-dimethylaminobenzoic acid

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.     

Flow-injection extraction-spectrophotometric determination of permanganate with the ethylene-bis(triphenylphosphonium) cation

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.     

Determination of seven trace elements in natural waters by neutron activation analysis after preconcentration with 1-(2-pyridylazo)-2-naphthol

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.     

Trace Analysis of Heavy Metals with Two New Disodium Bisdithiocarbamates

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.     

Darstellung und Charakterisierung von Chrom(V)- und Mangan(V)- nitridophthalocyaninen(1-) und -(2-): [MNPc(1-)]+; und [MNPc(2-)] (M=Cr,Mn)

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 (μ_eff = 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=Br_y, 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.     

Arsenazo, 2-(4-arsonophenyl(azo-7-(4-antipyril)azo-1,8-dihydroxy-3,6-naphtalene disulphonic acid as reagent for calcium ions. New parameters for metallochromic indicator characterization

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.     

Isonitroso-4-Methyl-2-Pentanone for Solvent Extraction and Spectrophotometric Determination of Palladium (II) at Trace Level

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.     

Structure and properties of 2-[(E)-2-(4-dipropylaminophenyl)-1-ethenyl]-1,3,3-trimethyl-3H-indolium chloride

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.     

Selective Spectrophotometric Determination of Palladium (II) With 2-(5-Bromo-2-Pyridylazo)-5-(Diethylamino)-Phenol

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.     

Metal complexes of 2-(2′-carboxymethylthio-phenylazo)-5-nitrotoluene—II. Complex formation equilibria with copper(II) ion in several dioxane—water solvent mixtures

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⁺ = CuA_n^(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.     

Sensitive spectrophotometric determination of vanadium with hydrogen peroxide and 2-(5-chloro-2-pyridylazo)-5-dimethylaminophenol after extraction with N-benzoyl-N-phenylhydroxylamine

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     

Spectrophotometric determination of gallium with 1-(2,4-dihydroxyphenylazo)-2-naphthol-4-sulfonic acid

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.     

Simultaneous First-Derivative Spectrophotometric Determination of Nickel and Manganese Complexes with 2-(2-Pyridylmethyleneamino)phenol

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.     

The structure and complexation equilibria of copper(II) with 4-(\bar 4-nitrophenyl)azo-2-phenyloxazolin-5-one

Summary A spectrophotometric method for determining trace amounts of Cu^II using 4-( -nitro-phenyl)azo-2-phenyloxazolin-5-one has been devised. With this reagent, Cu^II 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.     

Determination of platinum metals complexes with 2-(6-methyl-2-benzothiazolylazo)-5-diethylaminophenol by reversed-phase high performance liquid chromatography

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%.     

Potentiometric study on the complex equilibria between ni(ii) and mn(ii) and 3-(2-furyl)-2-mercaptopropenoic and 3-(2-furyl)-2-mercaptopropanoic acids

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.     

Solvent extraction of Mn/II/ with 2-propionyl, 1-naphthol oxime/2-PRONAPOX/ into chloroform

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/.     

Sensitive spectrophotometric determination of vanadium with hydrogen peroxide and 2-(5-chloro-2-pyridylazo)-5-dimethylaminophenol after extraction with N-benzoyl-N-phenylhydroxylamine

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.