Ternary complex of molybdenum(VI) with 4-nitrocatechol and tetrazolium blue chloride and its application to extraction-spectrophotometric analysis of ferrous metallurgy products

The formation of a new tenary complex of molybdenum(VI) with 4-nitrocatechol (NC) and tetrazolium blue chloride (BTC), which is easily extractable from water into dichloroethane, is reported. The optimum extraction conditions (pH, concentration of the reagents, extraction time) and composition of the complex (Mo: NC: BTC = 1: 2: 1) were found. The spectrophotometric parameters of the extract were determined as well. Beer’s law is obeyed for concentrations of Mo ranging from 0.2 to 6.7 μg/mL with the molar absorptivity λ₄₄₅ = 2.38 × 10⁴ L mol⁻¹ cm. A precise, sensitive, and simple method for determination of Mo in steels and ferromolybdenum was developed. The text was submitted by the authors in English.     

A Spectrophotometric Study of the Molybdenum(VI)-1-Pyrrolidinecarbodithioate System

Abstract

A spectrophotometric study of the molybdenum-1-pyrrolidinecarbodithioate complex has shown that the meta1:ligand ratio is 1;2. Both molybdenum(VI) and molybdenum(V) form complexes with almost identical absorption spectra. The conditional extraction constant for the molybdenum(VI)-1-pyrrolidinecarbodithioate in chloroform system has been evaluated as 6.3 × 10¹⁶.     

Determination of manganese by a new spectrophotometry method using toluidine blue

The formation of the ion associate of manganese(VII) with Toluidine Blue is studied spectropho-tometrically in water-organic media. The composition of the complex is established as TB: MnO₄ ^- =1:1. The molar absorptivity ε290 = (2.46 ± 0.09) × 10⁴ L/mol cm is determined. The selectivity of the reaction is studied and the method for determination of manganese(VII) 0.1—2.9 fug/mL is developed. Investigations of extraction in the system discussed were carried out. The characteristic values for the extraction equilibrium and the equilibrium in the aqueous phase were determined: extraction constant K_ex = 1 × 10⁴, distribution constant KD = 26.08, and association constant β = 3.83 × 10². A rapid and selective extractive-photometric method for the determination of manganese(VII) in plants was proposed.     

Spectrophotometric determination of piroxicam

The possibility of the spectrophotometric determination of piroxicam based on the extraction of its ion associate (IA) with the polymethine dye, 5-thiocyanate-1,3,3-trimethyl-2[(1E)-3-[(2E)-1,3,3-trime-thyl-1-H-indol-2-ilidine]-propenyl]-3H-indolium chloride. The maximal recovery of IA with toluene is achieved when pH of the aqueous phase is 8.0–12.0 and the concentration of the dye is (1.0–2.0) × 10⁻⁴. The molar absorption coefficient of IA is 8 × 10⁴, the detection limit of piroxicam is 0.49 μg/mL. A procedure has been developed for the extraction-spectrophotometric determination of piroxicam in the concentration range 1.0–20.0 μg/mL.     

Investigation of calcium antagonist–L-type calcium channel interactions by a vascular smooth muscle cell membrane chromatography method

The dissociation equilibrium constant (K _D) is an important affinity parameter for studying drug–receptor interactions. A vascular smooth muscle (VSM) cell membrane chromatography (CMC) method was developed for determination of the K _D values for calcium antagonist–L-type calcium channel (L-CC) interactions. VSM cells, by means of primary culture with rat thoracic aortas, were used for preparation of the cell membrane stationary phase in the VSM/CMC model. All measurements were performed with spectrophotometric detection (237 nm) at 37 °C. The K _D values obtained using frontal analysis were 3.36 × 10⁻⁶ M for nifedipine, 1.34 × 10⁻⁶ M for nimodipine, 6.83 × 10⁻⁷ M for nitrendipine, 1.23 × 10⁻⁷ M for nicardipine, 1.09 × 10⁻⁷ M for amlodipine, and 8.51 × 10⁻⁸ M for verapamil. This affinity rank order obtained from the VSM/CMC method had a strong positive correlation with that obtained from radioligand binding assay. The location of the binding region was examined by displacement experiments using nitrendipine as a mobile-phase additive. It was found that verapamil occupied a class of binding sites on L-CCs different from those occupied by nitrendipine. In addition, nicardipine, amlodipine, and nitrendipine had direct competition at a single common binding site. The studies showed that CMC can be applied to the investigation of drug–receptor interactions.     

Flavonol Derivatives for Determination of Cr(III) and W(VI)

 Simple, rapid, sensitive and selective methods for the determination of Cr(III) and W(VI) with flavonol derivatives in the presence of surface-active agents are proposed. In the pH ranges 3.4–4.2 and 1.9–2.5, the molar absorptivities of Cr(III)-morin-emulsifier S (EFA) and W(VI)-morin-polyvinylpyrrolidone (PVP) systems are 1.13×10⁵ and 2.13×10⁴ L mol⁻¹ cm⁻¹ at 435 and 415 nm, respectively. The Cr(III)-quercetin-PVP and W(VI)-quercetin-cetylpyridinium bromide (CPB) systems are formed in the pH ranges 4–4.6 and 2.2–2.8 with molar absorptivities 1.02×10⁵ and 9.02×10⁴ L. mol⁻¹ cm⁻¹ at 441 and 419 nm, respectively. The linear dynamic ranges for the determination of Cr(III) and W(VI) with morin in the presence of EFA and PVP are 0.03–0.46 and 0.71–8.1 μg mL⁻¹, respectively. The corresponding ranges with quercetin are 0.04–0.54 and 0.14–2.1 μg mL⁻¹ of Cr(III) and W(VI), respectively. The r.s.d (n = 10) for the determination of 0.25 and 3.7 μg mL⁻¹ of Cr(III) and W(VI) with morin and their detection limits are 0.88 and 0.99% and 0.016 and 0.63 μg mL⁻¹, respectively. Using quercetin, the r.s.d (n = 10) for 0.22 and 1.2 μg mL⁻¹ of Cr(III) and W(VI) and their detection limits are 0.92 and 0.91% and 0.015 and 0.08 μg mL⁻¹, respectively. The critical evaluation of the proposed methods is performed by statistical analysis of the experimental data. The proposed methods are applied to determine Cr in steel, non-ferrous alloys, wastewater and mud filtrate and to the determination of W in steel. Received March 8, 1999. Revision January 21, 2000.     

Extraction,Spectrophotometric and Atomic Absorption Spectrophotometric Determination of Molybdenum with Caffeic Acid and Application in High Purity Grade Steel and Environmental Samples

Abstract

A new selective and sensitive method for extraction of yellow Mo (VI)-caffeic acid complex with a liquid ion exchanger, Aliquat 336 from 4.0 pH, and spectrophotometric determination of molybdenum in trace amounts is described. the molar absorptivity of the complex is 1.1 × 10⁵ 1 mol^?1 cm^?1 at 340 nm and the colour system obeys Beer's law in the range 0.04–0.99 ppm of Mo(VI). the molybdenum is also determined with AAS and the method is applied for its determination in steel and environmental samples.     

Differential kinetic thermal lens determination of aniline and 4-nitroaniline

Thermal lens spectrometry was used for the differential kinetic determination of aniline (over the concentration range of 8 × 10⁻⁴–3.2 × 10⁻³ M) and 4-nitroaniline (2 × 10⁻⁴–1.6 × 10⁻³ M) present in combination in a single sample based on the oxidation reaction with periodate ions in an acidic medium (this determination is not possible with the spectrophotometric monitoring of the rate of reaction). The thermal lens procedure (λ_e = 488.0 nm; 80 mW) was characterized by good performance characteristics in the determination of aniline (c _min = 3 × 10⁻⁴ M; c _d = 8 × 10⁻⁴ M) and 4-nitroaniline (c _min = 7 × 10⁻⁵ M; c _d = 2 × 10⁻⁴ M), simplicity, and rapidity.     

Spectrophotometric Determination of Rhenium(IV) with Thiocyanate,TX-100 and N,N′-Diphenylbenzamidine

A spectrophotometric method to determine rhenium(IV) at trace level is based on the extraction of Re(IV)-SCN^? complex in sulphuric acid media with N,N′-diphenylbenzamidine(DPBA) in presence of a non-ionic surfactant triton X-100 (TX-100) in chloroform. The complex shows maximum absorbance at 435 nm with amolar absorptivity value of 4.24 × 10⁴ L mol^?1 cm^?1 at an acidity range 3.5-6.5 M H₂SO₄. The method followed Beer's Law for the system Re(IV)-SCN^?(TX-100)-DPBA upto 4.0 μg Re(IV) mL^?1. The detection limit of the method is 5 ppb. None of the tested foreign ions, except molybdenum(VI), interfere with the determination of rhenium. The interference due to molybdenum could effectively be removed by prior precipitation with oxine. The effect of various analytical parameters on the extraction of the metal are discussed.     

Investigation of 2-[2-(4-Methoxy-phenylamino)-vinyl]-1,3,3-trimethyl-3H-indolium Chloride as a New Reagent for the Determination of Chromium(VI)

 The complex formation and extraction of chromium(VI) with 2-[2-(4-methoxy-phenylamino)-vinyl]-1,3,3-trimethyl-3H-indolium chloride reagent was studied by means of spectrophotometry. The influence of medium acidity, the concentration of chloride ions and dye reagent, the nature of the extractant and some other factors (time of extraction, stability of color, interference, etc.) on the absorbance of colored extracts were studied. The optimum conditions were found to be 0.02–0.1 M H₂SO₄, 1.0–1.5 M NaCl, (2.0–2.5) × 10⁻⁴ M of reagent. The absorbance of the colored extracts obeys Beer’s Law in the range of 0.26–7.28 mg L⁻¹. The procedure of Cr(VI) extraction and spectrophotometric determination was examined. Author for correspondence. E-mail: andruch@kosice.upjs.sk Received November 19, 2002; accepted March 10, 2003 Published online June 13, 2003     

Application of a ternary complex of tungsten(VI) with 4-nitrocatechol and thiazolyl blue for extraction-spectrophotometric determination of tungsten

A new ternary ion-association complex of tungsten(VI), 4-nitrocatechol (NC), and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (Thiazolyl Blue, MTT) was obtained and studied using an extraction-spectrophotometric method. The optimum pH, reagent concentrations, and extraction time were determined. The composition of the complex was found to be W(VI): NC: MTT = 1: 2: 2. The extraction process was investigated quantitatively and the key constants were calculated. The molar absorptivity of the chloroform extract at λ_max = 415 nm was 2.8 × 10⁴ dm³ mol⁻¹ cm⁻¹, and the Beer’s law was obeyed up to 8.8 μg cm⁻³ tungsten(IV). The limit of detection and limit of quantification were calculated to be 0.27 μg cm⁻³ and 0.92 μg cm⁻³, respectively. The effect of foreign ions and reagents was studied and a competitive method for determination of tungsten in products from ferrous metallurgy was developed. The residual standard deviation and the relative error were 0.53 % and 0.2 %, respectively.     

Chemiluminescence determination of chromium(III) and total chromium in water samples using the periodate-lucigenin reaction

A new chemiluminescence (CL) method combined with flow injection technique is described for the determination of Cr(III) and total Cr. It is found that a strong CL signal is generated from the reaction of Cr(III), lucigenin and KIO₄ in alkaline condition. The determination of total Cr is performed by pre-reduction of Cr(VI) to Cr(III) by using H₂SO₃. The CL intensity is linearly related to the concentration of Cr in the range 4.0 × 10⁻¹⁰–1.0 × 10⁻⁶ g mL⁻¹. The detection limit (3s _b) is 1 × 10⁻¹⁰ g mL⁻¹ Cr and the relative standard deviation is 1.9% (5.0 × 10⁻⁸ g mL⁻¹ of Cr(III) solution, n = 11). The method was applied to the determination of Cr(III) and total Cr in water samples and compared satisfactorily with the official method.     

Spectroscopic study of 2,3-Bis(p-methoxybenzoyl)cyclopentadiene as potential iron(III)-chelating agent

2,3-Bis(p-methoxybenzoyl)cyclopentadiene was studied as iron(III)-chelating agent. Its pK _a value was determined by spectrophotometry (pK _a = 8.27 ± 0.02 at 25 ± 0.1°C; λ = 421 nm). 2,3-Bis(p-methoxybenzoyl)cyclopentadiene reacts with Fe³⁺ ions in aqueous ethanol (1:1, by volume) to give a 2:1 ligandmetal complex. The effects of different factors on the complex formation were studied. The reaction of 2,3-bis(p-methoxybenzoyl)cyclopentadiene with Fe³⁺ ions can be used as an alternative method for spectrophotometric determination of iron(III) in a range of concentrations from 0.1 to 1 μg cm⁻³, where the Beer law is fulfilled with a correlation coefficient of 0.9992. The results of spectrophotometric determination of iron(III) in geological materials (iron rock) showed very good agreement with those obtained by the atomic absorption measurements. Published in Russian in Zhurnal Obshchei Khimii, 2006, Vol. 76, No. 5, pp. 790–793. The text was submitted by the authors in English.     

Mass Spectrometric Determination of Association Constants of Bovine Serum Albumin (BSA) with para-Sulphonato-Calix[n]arene Derivatives

Electrospray Ionization Mass Spectrometry (ESI/MS) has been used to determine the association constants (K_As) and binding stoichiometries for parent para-Sulphonato-calix[n]arenes and their derivatives with bovine serum albumin (BSA). K_A values were determined by titration experiments using a constant concentration of protein. K_A measurements were carried out in a methanol–formic acid solution. 5,11,17,23–tetra-Sulphonato-calix[4]arene (1a) and 25-mono-(2-aminoethoxy)-5,11,17,23-tetra-Sulphonato-calix[4]arene (1d) interact strongly with BSA showing 3 non-equivalent binding sites with K_A1 = 7.69 × 10⁵ M⁻¹, K_A2 = 3.85 × 10⁵ M⁻¹, K_A3 = 0.33 × 10⁵ M⁻¹ and K_A1 = 1.69 × 10⁵ M⁻¹, K_A2 = 2.94 × 10⁵ M⁻¹, K_A3 = 0.60 × 10⁵ M⁻¹, respectively. The strength of the interactions between the calixarene and BSA is inversely proportional to the size of macrocyclic ring: n = 4 > n=6>>n=8.     

Adsorption of Cu(II), Cd(II), Pb(II), Cr(VI) by double hydroxides on the basis of Al oxide and Zr, Sn, and Ti oxides

It was studied the equilibrium adsorption and adsorption kinetics of Cu(II), Cd(II), Pb(II), and Cr(VI) by composite hydroxides formed by Me _x O _y · nH₂O and Me_0.4–0.7Al_0.6–0.3O _y · nH₂O, where Me = Zr, Sn and Ti. It was estimated the values of the diffusion coefficients of adsorbed ions Cu(II) and Cr(VI) from kinetic values. It was established that the estimated diffusion coefficients of adsorbed ions Cu(II) are in the range 0.4 × 10⁻¹²–2.5 × 10⁻¹² m²/s for individual hydroxides and 1.2 × 10⁻¹²–2.8 × 10⁻¹² m²/s for double hydroxides. The obtained values of diffusion coefficients Cr (VI) for double hydroxides are 0.1 × 10⁻¹⁰–0.4 × 10⁻¹⁰ m²/s.     

The sorption of molybdenum(VI) by ionites from solutions in hydrochloric acid

The sorption of molybdenum(VI) by KU-2 × 8 and AV-17 × 8 ionites from solutions in hydrochloric acid (1 × 10⁻⁵−6 N) was studied. Changes in the sorption of molybdenum(VI) by cationite and anionite were observed. The isoelectric point of molybdenum in solutions in hydrochloric acid was determined from sorption and electrical migration measurements.     

3-Hydroxy-2-(2-thienyl)-4H-chromen-4-one as a new reagent for the extraction and trace determination of molybdenum(VI)

A simple, sensitive and selective method for the extraction and trace determination of molybdenum(VI) has been developed; it is based on its reaction with 3-hydroxy-2-(2-thienyl)-4H-chromen-4-one (HTC) in sulphuric acid medium. The 1:2 Mo (VI)-HTC yellow complex is quantitatively extractable into chloroform (_max 420 nm) and is stable for more than 4 h. The procedure eliminates the interference of a large number of metal ions and complexing agents. Beer's law is obeyed in the range of 0–2.85 g Mo/mL with a molar absorptivity, Sandell's sensitivity and standard deviation of 5.28×10⁴ L mol^–1 cm^–1, 0.0018 g Mo/cm² and ±0.0054, respectively. The method has successfully been used for the spectrophotometric determination of molybdenum in steel samples.     

Extraction-spectrophotometric investigations on two ternary ion-association complexes of gallium(III)

Complex formation and liquid-liquid extraction were studied in systems containing Ga(III), azoderivative of resorcinol {4-(2-pyridylazo)resorcinol (PAR) or 4-(2-thiazolylazo)resorcinol (TAR)}, 2,3,5-triphenyltetrazolium chloride (TTC), water and chloroform. The optimum conditions w.r.t. pH, extraction time, concentration of ADR and concentration of TTC for the extraction of Ga(III) as an ion-associate complex were found.. The composition of the extracted complexes, (TT⁺)[Ga(PAR)₂] (I), (TT⁺)[Ga(TAR)₂] (II) or (TT⁺)₂[Ga(OH)(TAR)₂] (III), and the constants of association (β) between 2,3,5-triphenyltetrazolium cation (TT⁺) with corresponding anionic chelates were established by several methods. The constants of distribution (K_D) and extraction (K_ex) of the principal species I and III were determined as well. The apparent molar absorptivities of the chloroform extract at the optimum extraction-spectrophotometric conditions were ɛ′₅₁₀=9.5×10⁴ L mol⁻¹ cm⁻¹ (I) and ɛ′₅₃₀=4.6×10⁴ L mol⁻¹ cm⁻¹ (III). The validity of Beer’s law was checked and analytical characteristics that were calculated are reported herein.      

Extraction equilibria and spectrophotometric determination of vanadium(V) with 4-nitrocatechol and the ion-pair reagent thiazolyl blue tetrazolium

The formation and liquid-liquid extraction of a yellow ternary complex of vanadium(V) with 4-nitrocatechol (NC) and the ion-pair reagent Thiazolyl Blue Tetrazolium ⨑ub;3-(4,5-dimethyl-2-thiazol)-2,5diphenyltetrazolium bromide, MTT⫂ub; with 1: 2: 3 stoichiometry (V: NC: MTT) was studied. The optimum extraction conditions (pH, concentration of the reagents, extraction time), spectrophotometric parameters of the extract and key constants (extraction constant, association constant, distribution constant) were determined. Beer’s law was obeyed for concentrations ranging from 0.12 to 1.2 μg/mL of vanadium(V) with a molar absorptivity of ɛ = 3.13 × 10⁴ L/mol cm at λ_max = 400 nm. The effect of diverse ions was studied and extraction-spectrophotometric procedures for determination of vanadium in catalysts and steels were proposed.     

Batch and dynamic extraction of uranium(VI) from nitric acid medium by commercial phosphinic acid resin,Tulsion CH-96

Batch and dynamic extractions of uranium(VI) in 10⁻³–10⁻²M concentrations in 3–4M nitric acid medium have been investigated using a commercially available phosphinic acid resin (Tulsion CH-96). The extraction of uranium(VI) has been studied as a function of time, batch factor (V/m), concentrations of nitric acid and uranium(VI) ion. Dual extraction mechanism unique to phosphinic acid resin has been established for the extraction of uranium(VI). Distribution coefficient (K _d ) of uranium(VI) initially decreases with increasing concentration of nitric acid, reaches a minimum value at 1.3M, followed by increases in K _d . A maximum K _d value of ∼2000 ml/g was obtained at 5.0M nitric acid. Batch extraction data has been fitted into the linearized Langmuir adsorption isotherm. The performance of the resin under dynamic extraction conditions was assessed by following the breakthrough behavior of the system. Effect of flow rate, concentrations of nitric acid and uranium ion in the feed on the breakthrough behavior of the system was studied and the data was fitted using Thomas model.