Extractive Determination of Vanadium in Fungi Samples

A new reagent system has been reported for the extractive separation and simultaneous spectrophotometric de termination of vanadium (V). The method is based on the formation of a water in soluble blue‐violet V(V) complex with N‐hydroxy‐N‐m‐tolyl‐N′‐phenylbenzamidine (HTPBA), and neutral surfactant Triton X‐100 into chloroform over an acidity range of 1.0–10.0 M acetic acid. The complex shows a broad absorption maximum at 570 nm, when measured against a chloroform blank. The λ_max (570 nm) of the complex and that of re agent (313 nm) are well separated, hence the excess of the reagent does not interfere in the spectrophotometric de termination of the metal. The molar absorptivity (?) of the complex is (4.74) × 10³ 1 mol^?1 cm^?1. The linearity of the calibration curve is followed between 0.5–12.0 μg mL^?1 with slope, intercept and correlation coefficient of 9.16× 10^?2, 4.5 × 10^?3 and 0.999, respectively. The detection limit of the method is 45 μgl^?1. The proposed re agent system provides significantly higher tolerance limit for iron (500 μg mL^?1) and also various metalions commonly associated with vanadium did not interfere. The method was applied for the deter mi nation of vanadium content of three samples i.e. Spirogyra, Puccinia and Riccia.     

Mixed Ligand Complexes of Vanadium(V): Extraction With Some New Hydroxamic Acids and Application in Steel.,Rock and Environmental Anaysis

Abstract

Five new substitued hydroxamic acids are used for extraction and spectrophotometric determination of vanadium(V) in trace amounts. the binary complex of vanadium (V) with H-p-ciloropheny 1-3,4,5-trimethoxycinnamohdroxamic acid (PTCHA) and the mixed ligand complex of vanadium (V) with N-p-cinlorpheny-p-chlorophenoxyisobutyrohydroxamic acid (PP3HA) and thiocyanete were studied. The molar absorbtivities of the bluish violet vanadium(V) hydroxamate and mixed ligand complexes are 6.9 × 10³ and 1.1 × 10⁴ cm³ mol^?3 cm^?1, respectively. The vanadium is also determined with AAs and the method is applied for its determination in steel. alloy, rock and environmental samples.     

Extraction,Spectrophotometric, and Atomic Absorption Spectrophotometric Determination of Selenium With N-Phenylbenzohydroxamic Acid

Abstract

Solvent extraction spectrophotometric and atomic absorption spectrophotometric methods for the determination of selenium(IV) in microgram quantities are described. The selenium(IV) forms yellow colored complex with N-phenylbenzohydroxamic acid (PBHA) extractable into chloroform from 7 M HClO₄. Se-PBHA complex has maximum absorbance at 345 nm with a molar absorptivity 1.5 × 10⁵ 1 mol^?1 cm^?1 and Sandell's sensitivity 0.000526 μg /cm². Effect of molarity, reagent concentration, diverse ions on the extraction of selenium complex were studied. The selenium is determined in presence of tellurium.     

Analytical applications of picolinealdehyde salicyloylhydrazone: II. Extraction and spectrophotometric determination of vanadium(V)

Picolinealdehyde salicyloylhydrazone reacts with vanadium(V) to produce a yellow 1:1 complex (λ_max = 400 nm, ? = 2.17 × 10⁴ liters · mol^?1 cm^?1) in aqueous ethanolic solution. The yellow complex can be extracted into chlorobenzene (λ_max = 425 nm, ? = 2.16 × 10⁴ liters · mol^?1 cm^?1) and used for the spectrophotometric determination of trace amounts of vanadium. Interferences have been investigated. The method has been applied to the determination of vanadium in steel and in lead concentrates.     

Extractive Spectrqphotometric Determination of Vanadium Liith o-Aminobenzo-Hydroxamic Acid

Abstract

A new spectrophotometric method for vanadium determination is proposed. The method is based on the extraction in Adogen-toluene solution of the complex formed between V(V) and o-Aminobenzohydraxámic acid

The method allows determination of 50 to 110 μg of V(V). The error and the apparent molar absorptivity are 1.2% and 5.2 ± 10³ l.mol^?1. cm^?1 respectively. The interferences caused by foreign ions have been established. The method is applied with success to determination of vanadium in petroleum crudes.     

First Electroanalytical Methodology for the Determination of Hordenine in Dietary Supplements using a Boron‐doped Diamond Electrode

The present work describes the first electrochemical investigation and a simple, rapid and modification‐free electroanalytical methodology for quantification of hordenine (a potent phenylethylamine alkaloid) using a boron‐doped diamond electrode. At optimized square‐wave voltammetric parameters, the observed oxidation peak current in 0.1 M HClO₄ at +1.33 V (vs. Ag/AgCl) increased linearly from 5.0 to 100 μg mL^?1 (3.0×10^?5–6.1×10^?4 M), with detection limit of 1.3 μg mL^?1 (7.8×10^?6 M). The applicability of the developed method was tested with the determination of hordenine in the commercial dietary supplement formulations.     

Liquid-liquid extraction and cloud point extraction for spectrophotometric determination of vanadium using 4-(2-pyridylazo)resorcinol

Liquid-liquid extraction (LLE) and cloud point extraction (CPE) of vanadium(V) ternary complexes with 4-(2-pyridylazo)resorcinol (PAR) and 2,3,5-triphenyl-2H-tetrazolum chloride (TTC) were investigated. The optimal conditions for vanadium extraction and spectrophotometric determination were identified. The composition (V: PAR: TTC) of the extracted species was 1:2:3 (optimal conditions; LLE), 2:2:2 (low reagents concentrations; LLE), 1:1:1 (short heating time;CPE), and 1: 1: 1 + 1: 1: 0 (optimal extraction conditions; CPE). LLE, performed in the presence of 1,2-diaminocyclohexane-N,N,N′,N′-tetraacetic acid and NH₄F as masking agents, afforded the sensitive, selective, precise, and inexpensive spectrophotometric determination of vanadium. The absorption maximum, molar absorptivity, limit of detection, and linear working range were 559 nm, 1.95 × 10⁵ dm³ mol^?1 cm^?1,0.7 ng cm^?3, and 2.2–510 ng cm^?3, respectively. The procedure thus developed was applied to the analysis of drinking waters and steels. The relative standard deviations for V(V) determination were below 9.4 % (4–6 × 10^?7 mass %; water samples) and 2.12 % (1–3 mass %; steel samples).     

Analytical applications of 4-(4′-methyl-2′-thiazolylazo)-2-methyl-resorcinol: Spectrophotometric determination of vanadium

4-(4′-Methyl-2′-thiazolylazo)-2-methyl-resorcinol reacts with vanadium (V) to produce a bluish-violet 1:1 complex (λ_max = 560 nm, ? = 2.50 × 10⁴M^?1 · cm^?1, 50% methanol-water medium), which allows the spectrophotometric determination of 0.1 to 1.4 ppm of vanadium. The method has been applied to the determination of vanadium in several low-alloy steels.     

Spectrophotometric determination of vanadium using variamine blue and its application to synthetic, environmental and biological samples

A simple, rapid and accurate spectrophotometric method is described for the determination of trace amounts of vanadium using variamine blue (VB) as a chromogenic reagent. The method is based on the oxidation of variamine blue to form a violetcolored species on reaction with vanadium(V), having an absorption maximum at 570 nm. Beer’s law is obeyed in the range of 0.1–2.0 μg ml^?1. The molar absorptivity and Sandell’s sensitivity were found to be 1.65 × 10⁴ l mol^?1 cm^?1 and 0.003 μg cm^?2, respectively. Optimum reaction conditions were evaluated in order to delimit the linear range. The effect of interfering ions on the determination is described. The proposed method has been successfully applied to the determination of vanadium in steel, pharmaceutical, environmental, and biological samples.     

Indirect Spectrophotometric Determination of Vanadium(IV) by Flow Injection Analysis Based on the Redox Reaction with Copper(II) in the Presence of Neocuproine

Abstract

An indirect photometric method with a continuous-flow analysis is presented for the determination of trace amounts of vanadium(IV). It is based on the redox reaction of copper(II) with vanadium(1V) in the presence of neocuproine. In the presence of neocuproine, copper(I1) is reduced easily by vanadium(I V) to a copper(1)-neocuproine complex, which shows a n absorption maximum at 454 nm. By measuring t h e absorbance of the complex at this wavelength, vanadium(1V) in t h e range 2×10^?6 - 8 × mol dm^?5 mol dm^?3 can be determined at a rate of 120 samples h^?1. The fractional determination of vanadium(1V) and iron(I1) is also studied.     

Analysis of Metal Ions in Environmental Samples - III Synergistic Determination of Vanadium (V) As its Mixed Complex with N-0-Methoxyphenyl-2-Thenohydroxamic Acid and 3-(0-Carboxyphenyl)-1-Phenyltriazine-N-0Xide

Abstract

A highly sensitive, selective, and rapid method for the spectrophotometry determination of vanadium(V) at trace levels is described. The method is based on the selective extraction of vanadium(v) from strongly acidic (3–6 M hydrochloric acid) met ium with solution of N-0-methoxyphenyl-2- thenohydroxamic acid (0MTHA) in chloroform. The extract is then equilibrated with 3-(0-carboxyohenyl)-1-phenyltriazine-N-oxide(CPPTNO) at pH ? 1.5 and the resulting colour is measured at 445 nm. The colour system obeys Beer's law over the range 0–20 -μg/ml of vanadium; the molar absorptivityat the wavelength of maximum absorption (445 nm), and the Sandell sensitivity of the method are 1.1 × 10⁴1. mole^?1 cm^?1 and 0.005 μg/ml respectively.     

Catalytic Adsorptive Stripping Voltammetry of Germanium(IV) in the Presence of Gallic Acid and Vanadium(IV)‐EDTA

A highly sensitive and selective catalytic adsorptive cathodic striping procedure for the determination of trace germanium is presented. The method is based on adsorptive accumulation of the Ge(IV)‐gallic acid (GA) complex onto a hanging mercury drop electrode, followed by reduction of the adsorbed species. The reduction current is enhanced catalytically by addition of vanadium(IV)‐EDTA. The optimal experimental conditions include the use of 0.03 mol/L HClO₄ (pH1.6), 6.0×10^?3 mol/L GA, 3.0×10^?3 mol/L V(IV), 4.0×10^?3 mol/L EDTA, an accumulation potential of ?0.10 V(vs. Ag/AgCl), an accumulation time of 120 s and a differential pulse potential scan mode. The peak current is proportional to the concentration of Ge(IV) over the range of 3.0×10^?11 to 1.0×10^?8 mol/L and the detection limit is 2×10^?11 mol/L for a 120 s adsorption time. The relative standard deviation at 5.0×10^?10 mol/L level is 3.1%. No serious interferences were found. The method was applied to the determination of germanium in ore, mineral water and vegetable samples with satisfactory results.     

Spectrophotometric determination of vanadium(V) as a mixed thiocyanate-4-pyridone complex

The spectrophotometric determination of vanadium(V) as a mixed thiocyanate-3-hydroxy-2-methyl-1-phenyl-4-pyridone (HX) complex and as a mixed thiocyanate-3-hydroxy-2-methyl-1-(4-tolyl)-4-pyridone (HY) complex is described. The extracted complexes in chloroform have a maximum absorbance at 450 and 650 nm. The optimal conditions for the extraction and spectrophotometric determination of vanadium(V) are determined. The solutions of the V-SCN-HX and V-SCN-HY complexes in chloroform obey Beer's law in the range 1–10 ppm of vanadium, and are stable for at least 24 hr. The molar absorptivity of the method is 6.8 × 10³ liters mol^?1 cm^?1. The molar ratio V:SCN:HX (HY) of the extracted complex is 1:1:2.     

Extraction-Spectrophotometric Determination of Arsenic in Environmental Samples with Iodide and Amidines

Abstract

A simple and rapid method for the spectrophotometric determination of traces of total arsenic present in industrial waste waters is described. It is based on the reaction of As(III) with I^? in 5 –6 M HCl, and extraction of the iodo-arsenite complex formed into chloroform with amidines. The molar absorptivity of AsI₄ ^? with 11 different amidines is in the range (3.9 –7.9) × 10³ lmol^?1 cm^?1 at λ_max = 380 –395 nm; the simplest compound, N,N′-diphenylbenzamidine (DPBA) has been chosen for further studies. The limit of detection with DPBA is 0.1 μg As/ml. The method is highly selective with almost no interference from all anions and cations tested.     

Trace Analysis of Vanadium in Environment as its Ternary Complex with N-p Methoxyphenyl-2-Furylacrylohydroxamic Acid and 3-(o-Carboxyphenyl)-1-Phenyltriazine-N-Oxide

Abstract

A method is presented for the highly sensitive, selective, and rapid determination of vanadium (V) at sub-microgram levels in rocks, animal tissues, plant tissues and natural waters. The method is based on the selective extraction of vanadium (V) from strongly acidic (3-8 M hydrochloric acid) medium with solution of N-p-methoxyphenyl-2-furylacrylohydroxamic acid (MFHA) in chloroform. The reddish-violet extract (molar absorbance 8.6x10³ 1 mole^?1 cm^?1 at λ max 545 nm) is then equilibrated with 3-(o-carboxyphenyl)-1-phenyltriazine-N-oxide (CPPTNO) at pH = 1.5. The resulting ternary complex has enhanced colour (molar absorbance 1.4 × 10⁴ 1 mole^?1 cm^?1 at Λ max 450 nm). The ternary system obeys Beer's Law at 450 nm over the range 0-18 μ g/ml of vanadium. The extraction system achieves 20-fold enrichment of vanadium and enables the determination of the metal down to parts per billion (ng 1^?1) levels. The method tolerates the presence of a large number of anions and cations which are normally present with vanadium in rocks, plant tissues, animal tissues and natural waters. The applicability of the method was tested by the analysis of vanadium in these matrices. MFHA was selected from nine hydroxamic acids as it provided maximum sensitivity and selectivity.     

Cyclohexane-1, 3-Dione bis (4-Methylthiosemicarbazone) as a Spectrophotometric Reagent for the Determination of Zn (II)

Abstract

The spectrophotometric study of reddish cyclohexane-1, 3-dione bis (4-methylthiosemicarbazone)-Zn(II) was made in dimethylformamide-water solution (λ_max= 475 nm, ∑ = 3.3×10⁴ 1.mole^?1. cm^?1. Sandell sensitivity = 2×10^?2 μg Zn(II).cm^?2, stoichiometry 1:1, and apparent stability constant 6.1×10⁴). A new method for the spectrophotometric determination of Zn(II) is proposed for concentrations between 0.1 and 2.5 ppm. The relative error (95% confidence level) is 0.7% for 1.0 pprn of Zn(II).

The extraction with ethylacetate of the reddish complex was also studied spectrophotometrically (λ_max = 493 nm, ∑ in organic phase = 4.8×10⁴ 1.mole^?1.cm. Sandell sensitivity = 3.4×10^?4 μg Zn(II).cm^?2, stoichiometry 1:1, apparent extraction constant 1.4×10⁴). A new method for the extraction-spectrophotometric determination of Zn(II) is proposed for concentrations, in aqueous phase, between 0.02 and 0.30 ppm. The relative error (95% confidence level) is 1.0% for 0.15 pprn of Zn(II).     

Extraction-spectrophotometric study on the vanadium(V)-2,3-dihydroxynaphthalene — iodonitrotetrazolium chloride — water — chloroform system and its analytical application

The formation of a new ternary ion-associate complex of vanadium(V) with 2,3-dihydroxynaphthalene and iodonitrotetrazolium chloride with a composition ratio of 1:2:1 is reported. The complex is quantitatively extracted from water into chloroform. The molar absorptivity (ɛ) of the extract at λ _max=340 nm is 2.5 × 10⁴ dm³/mol cm, and Beer’s law is obeyed for concentrations ranging from 0.1 to 0.9 μg/cm³ V(V). The following constants are determined: the extraction constant, the association constant, the distribution constant, and the recovery factor. The effects of foreign ions and reagents are studied. A selective and sensitive method is developed for determination of vanadium in steels.     

Pre-column chelation liquid chromatographic separation and determination of trace V,Cu, Co,Pd, Fe and Ni

Conditions for the separation by reversed-phase liquid chromatography (LC) of V(V), Cu(II), Co(III), Pd(II), Fe(III) and Ni(II) chelates with 2-(5-bromopyridylazo)-5-diethylaminophenol (5-Br-PADAP) were studied. Six species of metal chelates were separated successfully with methanol-acetonitrile-water (72:12:16, v/v/v) containing 0.13 M NaCl and 0.29 mM cetyltrimethylammonium bromide (pH 5.0) as the mobile phase on a Nucleosil C₁₈ (5 μm) column (250 × 4 mm i.d.).The conditions of the determination of these metal chelates are discussed. A simple and rapid method for the determination of trace amounts of V(V), Cu(II), Co(III), Pd(II) and Ni(II) simultaneously by reversed-phase LC has been developed. The detection limits are 5 × 10^?12, 1 × 10^?10, 3 × 10^?11, 5.3 × 10^?9 and 2 × 10^?10 g, respectively. The method is applied to the determination of these metals in natural waters and mineral samples.     

Spectrophotometric determination of vanadium(V) with methoxypromazine maleate and its application to vanadium steels and minerals

The reagent in 8-fold excess forms a violet species with vanadium(V) instantaneously in 1–3 M phosphoric acid. The absorption maximum is at 565 nm; the molar absorptivity is 1.65 × 10⁴ l mol^?1 cm^?1. Beer's law is obeyed over the range 0.1–6.5 mg l^?1 vanadium (V); the optimum range is 0.3–6.0 mg l^?1; the Sandell sensitivity is 3.1 ng cm^?2. The method is simple and selective. The method is applicable for the determination of vanadium in vanadium steels and minerals.     

Oxovanadium complex as potential nucleic acid binder

DNA binding study of a vanadium(V) complex, Oxo-chloro-bis-N-phenylbenzohydroxamto-vanadium(V), derived from N-phenylbenzohydroxamic acid(PBHA) form a violet color complex with vanadium (V) in presence of hydrochloric acid is performed using absorption, fluorescence and viscometric techniques. The binding parameters of the PBHA-V(V) complex using calf thymus DNA (ct-DNA) and torula yeast RNA (t-RNA) have been determined. The complex shows the ability of cooperatively minor groove binding with ct-DNA as indicated by remarkable hyperchromicity and a blue shift of the absorption spectra. Quenching of metal complex calculation was carried out with Stern-Volmer equation and K_sv was found to be 2.32 ± 0.18 × 10⁴ M^?1, while in the case of t-RNA, enhancement is observed and that means the compound was not able to displace the Ethidium Bromide(EB)-t-RNA complex. Molecular docking was also applied to predict the mode of interaction of the hydroxamic acid with ct-DNA and t-RNA. DNA binding results of the complex are compared with those of the parent ligand.