Spectrophotometric Determination Of Niobium Research Articles

Normal and second derivative spectrophotometric determination of niobium using solid phase extraction technique

This paper describes a rapid method for niobium preconcentration, separation and determination by using solid phase extraction (SPE). The activity level of 94Nb is still very low in the environment. However, on account of its long half life, 94Nb would be one of the important isotopes in the near future for the safe management of radioactive waste. SPE method using freshly precipitated microcrystalline naphthalene as an adsorbent has been developed to separate and preconcentrate trace amount of niobium from aqueous samples for the detection by normal and second derivative spectrophotometry. The influence of some analytical parameters on the quantitative recoveries of the Nb(V) was investigated by batch technique. The complex extracted on naphthalene has an absorption maximum at 380 nm. The optimum pH range for the sorption is 7–8. The molar absorptivity is 1.40 × 104 L/(mol cm), the sensitivity being 0.0066 µg/cm2 of niobium. Derivative spectrophotometry in conjunction with extractive pre-concentration of Nb(V) with SPE is used for determining Nb(V) at concentration levels down to 25 ppb in initial sample. The foreign ions interference has been studied and the optimized conditions developed were utilized successfully for the trace determination of niobium in alloy steel, environmental and wastewater samples.

Spectroscopic Investigation of the Complex Formation of Niobium Using 2,6-Dithiolphenol and Aminophenols

A new, simple, precise, selective and sensitive method for the extraction and spectrophotometric determination of niobium has been described. Mixed-ligand complexes of Niobium (V) with 2,6-dithiolphenol (DTP) and aminophenols (AP) have been studied by spectrophotometry. Extraction of mixed-ligand complexes is maximal at pH 3.6 - 5.0. The optimal conditions for the formation and extraction of mixed-ligand compounds have been found. The molar ratio of the reacting species was 1:2:2 (Nb:DTP:AP). The Beer’s law was applicable in the range of 0.05 - 4.0 μg/ml. The method is free from common interferences. A procedure has been developed for extraction-spectrophotometric determination of Niobium in steel.

Extraction-spectrophotometric determination of niobium in magnetic alloys

The article describes spectrophotometric determination of niobium in magnetic alloys based on extraction of niobium from tartrate solutions with trioctylamine in toluene with subsequent generation of complex compounds with phenylfluorone in the extracted product. The procedure facilitates selective extraction of niobium separating it from such elements as Fe (II), Fe (III), Co, C, Si, Mn, S, P, Cr, Ni, V, W, Ti, Al, Cu, and B. The range of analyzed contents is 0.34–8.3%. The procedure has been tested in determination of niobium in magnetic alloys, and its validity has been approved by analysis of reference specimen SO 160-6.

Formation and Extraction of Niobium(V) Complex with Xylenol Orange in the Presence of a 4-Pyridone Derivative

Xylenol orange (XO) is a suitable reagent for the spectrophotometric determination of niobium in a weakly acidic medium. The present study shows that the addition of 3-hydroxy-2-methyl-1-phenyl-4-pyridone (HX) influences the complex formation as well as the spectroscopic properties of this colored system. To prevent formation of niobium(V) hydrolyzed species in water, tartaric acid was used when preparing the niobium stock solution. The red-violet colored complex formed by heating niobium(V) with xylenol orange (XO) in the presence of HX at pH=3 has a maximum absorption wavelength at 565 nm. The complex can be extracted by a chloroform solution of tetraphenylphosphonium (TPP) chloride. The optimum reaction conditions and other parameters for complex formation have been evaluated. The mechanism of extraction is probably based on the formation of the associated ion pair between the tetraphenylphosphonium cation and the mixed Nb(V)-XO-HX anion. The extracted complex in chloroform showed a maximum absorbance at 585 nm with the corresponding molar absorption coefficient being 3.72×104 L⋅mol−1⋅cm−1, and obeys Beer’s law in the range 3×10−6 to 3×10−5 mol⋅L−1.

Spectrophotometric Determination of Simultaneously Present Niobium and Tantalum

The formation of niobium(V) and tantalum(V) complexes of 2,3,4-trioxyphenylazo-5-sulfonaphthalene in the presence of cetyltrimethylammonium bromide was studied by spectrophotometry. The effect of surfactants on the chemical and analytical properties of niobium(V) and tantalum(V) complexes of this reagent was studied. Procedures were developed for the spectrophotometric determination of niobium and tantalum present simultaneously as mixed-ligand complexes. The procedures were tested on model solutions.

Flow Injection Extraction Spectrophotometric Determination of Niobium as the Ethylene Bis(triphenylPhosphonium) Thiocyanatoniobate(v)

ABSTRACT Niobium was determined by flow injection spectrophotometry at 393 nm after extraction of ethylene-bis(triphenylphosphonium)thiocyanatoniobate(V) into chloroform. The effects of diverse ions are reported. The system has been applied to the determination of niobium in steels by the method of standard additions.

Extractive spectrophotometric determination of niobium(V) using 3-hydroxyflavone

A simple, rapid method for the spectrophotometric determination of niobium in trace amounts is presented, employing 3-hydroxyflavone as a ligand for the complexation of the metal ion and extracting the coloured complex into chloroform from 4M HClO4 solution. Beer's law is obeyed in the range 0.0 to 3.2 μg ml−1 Nb(V), with a lower working limit of 0.1 μg ml−1 Nb(V). Molar absorptivity and Sandell's sensitivity of the complex at 395 nm are 4.088 × 104l mol−1 cm−1 and 0.002μg Nb(V) cm−2, respectively. The stoichiometry of the complex is established as 1∶2 by Job's and mole ratio methods. The method is free from the interference of a large number of analytically important elements. The proposed system handles satisfactorily the analysis of several samples of varying complexity. The results are highly reproducible with a relative standard deviation of 0.34% for 20 μg of Nb.

Extractive spectrophotometric determination of niobium(V) with 3-hydroxy-2-(2-thienyl)-4H-chromen-4-one

A coloured complex of niobium (V) with 3-hydroxy-2-(2-thienyl)-4H-chromen-4-one (HTC) is produced in perchloric acid medium (4 mol/L); it is quite stable and extractable into dichloromethane. Beer's law is obeyed in the range 0.0–1.9 μg Nb(V) mL−1. The molar absorptivity at λmax=420 nm is 5.0357×104 L mol−1 cm−1. Using Job's method and the mole ratio method, the ratio of metal to ligand (Nb:HTC) in the extracted species has been found to be 1:2. The effect of anions and foreign metals is described.

Solid-phase spectrophotometric determination of niobium in rocks after coprecipitation with iron quinolin-8-olate

A selective and sensitive method for the determination of niobium(v) in rocks was developed based on selective enrichment by coprecipitation and sensitive solid-phase spectrophotometric determination. In solid-phase spectrophotometry, niobium(v) was determined directly on a membrane filter as the Nbv—Sulfochlorophenol S complex fixed on the filter in the presence of zephiramine. The detection limit was 5 ng for 30 ml of sample solution. The selectivity was improved by coprecipitation using iron(III) quinolin-8-olate as a carrier precipitate (recovery >97.0%). For example, at least a 100-fold mass excess of tantalum(v) with respect to 0.3 µg of niobium(v) did not interfere in the determination. A 500-fold excess of vanadium(v) or hydrogen peroxide also did not interfere. The proposed method was applied to the determination of niobium in rock standard samples distributed by the Geological Survey of Japan. The results obtained for JB-1a, JG-1a, and JA-3 were 27.2 (27), 10.8 (12) and 3.04 (3) ppm, respectively (the proposed values are in parentheses).

Extraction and Spectrophotometric Determination of Niobium

Extraction and Spectrophotometric Determination of Niobium

Alternative spectrophotometric determination of niobium and tantalum with o-hydroxyhydroquinonephthalein in cationic surfactant micellar media

The alternative and simultaneous spectrophotometric determination of niobium and tantalum was examined by using the colour development between o-hydroxyhydroquinonephthalein (Qnph) and niobium or tantalum in the presence of hexadecyltrimethylammonium chloride (HTAC) in strong acidic media. Beer's law was obeyed up to 10.0 μg of niobium and up to 18.0 μg of tantalum in a final volume of 10.0 ml. The apparent molar absorption coefficients for niobium and tantalum were 2.18×105 and 2.09×105 l mol−1 cm−1 with Sandell's sensitivities of 0.00042 μg/cm2 niobium at 520 nm and 0.00085 μg/cm2 tantalum at 510 nm, respectively. The alternative assay of niobium and tantalum was possible by using two methods: Method A — masking method with oxalic acid, Method B — acid adjusting-method using 50% sulfuric acid. These methods were 2–6-times more sensitive than other methods.

Spectrophotometric determination of niobium after extraction with thiocyanate and 1-naphthylmethyltriphenylphosphonium chloride into microcrystalline 1,4-dichlorobenzene

Niobium (0–20) μg) can be determined spectrophotometrically at 393 nm after its adsorptive extraction as 1-naphthylmethyltriphenylphosphonium thiocyanatoniobate(V) with microcrystalline 1,4-dichlorobenzene after dissolution of the solid phase in 1,2-dichloroethane. The effects of reagent conditions, diverse ions and masking studies are reported. The system has been applied to the determination of niobium in steels.

Spectrophotometric Determination of Niobium through Heteropoly Blue formation

Spectrophotometric Determination of Niobium through Heteropoly Blue formation

Spectrophotometric determination of niobium(V) after extraction in the presence of thiocyanate with the ethylene-bis-(triphenylphosphonium) cation

Niobium(V) (0–20 μg) can be determined spectrophotometrically after its extraction as ethylene-bis- (triphenylphosphonium) thiocyanatoniobate(V) into chloroform. The effects of diverse ions and masking studies are reported. The system is applied to the determination of niobium in a range of steels.

Amidine for extraction and spectrophotometric determination of niobium(V) in the presence of thiocyanate

Amidine for extraction and spectrophotometric determination of niobium(V) in the presence of thiocyanate

Extraction and spectrophotometric determination of niobium by tetraphenylarsonium and phosphonium chloride from a hydrochloric acid solution

The extraction of niobium(V) in the form of a chloro complex has been studied. Radiometrical and spectrophotometrical studies show that niobium(V) is extracted practically completely from a solution containing more than 9 mol dm −3 chloride in the range of 2–5 M hydrogen ion concentration by chloroform solutions of tetraphenylarsonium (TPA) and tetraphenylphosphonium (TPP) chloride and that niobium is not extracted at chloride concentrations less than 6 mol dm −3. The mechanism of extraction is based on the formation of the ion-associated compounds that form between the onium cation and the oxotetra-chloroniobate(V) anion. The extracted complexes in chloroform have a maximum absorbance at 282 nm (TPA) and 285 nm (TPP); they obey Beer's law in the range of 1–10 μg Nb ml −1, and are stable for at least 24 hr. The molar absorptivity of the method is 1.33 × 10 4 dm 3 mol −1cm −1. The composition of the extracted species [(C 6H 5) 4 X] [NbOCl 4] where X = As or P was determined spectrophotometrically, radiometrically, and by characterization of the crystalline compounds isolated.

Spectrophotometric determination of niobium in steel by means of p-sulphobenzeneazo-4-(2,3-dihydroxypyridine)

Spectrophotometric determination of niobium in steel by means of p-sulphobenzeneazo-4-(2,3-dihydroxypyridine)

Solvent Extraction and Spectrophotometric Determination of Niobium and Tantalum-Quinizarin-3-Sulphonic Acid Complexes with Benzylamine, Dodecylamine and Tridecylamine in Benzene

Solvent Extraction and Spectrophotometric Determination of Niobium and Tantalum-Quinizarin-3-Sulphonic Acid Complexes with Benzylamine, Dodecylamine and Tridecylamine in Benzene

Rapid extraction and spectrophotometric determination of niobium with N‐P‐chlorophenyl‐benzohydroxamic acid

AbstractA rapid method has been described for the extraction and spectrophotometric determination of niobium with N‐p‐chlorophenylbenzohydroxamic acid by extraction of the complex into toluene from 8‐10 M HCl, containing stannous chloride. The complex gives the maximum absorbance at 365 nm and the molar absorptivity is being 3.0 × 104 1 mol−1 cm−1. It obeys Beer's law within the range of 0.3 ppm to 20 ppm.

Interference of trace amounts of nitrilotriacetic acid in ethylenediaminetetraacetic acid with the spectrophotometric determination of niobium as the niobium—edta—pyrocatechol complex

The effects of 10 -2–10 mol-% NTA in the EDTA used in this determination are reported. Satisfactory results are possible only if the NTA contamination is less than 0.05% ( w w ). Even analytical-grade EDTA from some sources may be grossly contaminated.