2-(2-Thiazolylazo)-p-cresol as a spectrophotometric reagent for vanadium determination in the presence of ascorbic acid

Teixeira, Leonardo Sena Gomes; Costa, Antônio Celso Spı́nola; Queiroz, Adriana S.; Amorim, Adelaide M. M.; Bomfim, Osvaldo N.; Ferreira, Sérgio Luís Costa

doi:10.1007/bf01246856

Cited by 8 publications

(4 citation statements)

References 16 publications

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“…In the interpretation of the obtained experimental results, we used information for the complex formation between V IV and ADs in the presence [32][33][34][35] or absence [23,[35][36][37][38] of auxiliary reagents. We suggested several structures of the chromogenic anionic part of the extracted species.…”

Section: Introductionmentioning

confidence: 99%

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Complex formation in a liquid-liquid extraction-chromogenic system for vanadium(IV)

et al. 2019

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The azo dye 4-(2-thiazolylazo)orcinol (TAO) and the cationic ion-pair reagent 2,3,5-triphenyl-2H-tetrazolium chloride (TTC) were examined as constituents of a water-chloroform extraction-chromogenic system for vanadium(IV). The effects of TAO concentration, TTC concentration, pH and extraction time were examined. Under the optimum conditions the extracted complex has a composition of 1:2:1 (V:TAO:TTC). The absorption maximum, molar absorptivity and constant of extraction were determined to be λmax=544 nm, ε544=1.75×104 dm3 mol–1 cm–1 and Log Kex=4.1. The ground state equilibrium geometries of the possible monoanionic VIV-TAO 1:2 species were optimized by the HF method using 3-21G* basis functions. Their theoretical time dependent electronic spectra were simulated and compared with the experimental spectrum. The best fit was obtained for the structure in which one of the TAO ligands is tridentate, but the other is monodentate (bound to VIV through the oxygen which is in the ortho-position to the azo group) and forms a hydrogen bond N–H...O=V through its protonated heterocyclic nitrogen. Based on this unusual structure, which can explain some peculiarities of the complex formation between VIV and commonly used azo dyes, the ground state equilibrium geometry of the whole ternary 1:2:1 complex was computed at the HF and BLYP levels.

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Section: Introductionmentioning

confidence: 99%

“…For stabilization of V IV reducing reagents, such as ascorbic acid (АА), are often added [14,33]. However, АА can enter the coordination entity and form ternary complexes in similar systems [33]. On the other hand, the reducing reagent can convert the tetrazolium salt to formazan [40].…”

Section: Introductionmentioning

confidence: 99%

Complex formation in a liquid-liquid extraction-chromogenic system for vanadium(IV)

et al. 2019

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“…It was first prepared Article *e-mail: lsgt@ufba.br by Kanenina 8 and its application as a spectrophotometric reagent have been studied 9 . In our laboratory TAC has been used for spectrophotometric determination of vanadium 10 , titanium 11 , lead 12 , indium 13 and nickel 14 . Application of micelles in analytical chemistry involves the beneficial alteration of metal ion-ligand complex spectral properties via surfactant association.…”

Section: Introductionmentioning

confidence: 99%

Spectrophotometric determination of uranium using 2-(2- Thiazolylazo)-p-Cresol (TAC) in the presence of surfactants

Teixeira¹,

Costa²,

Ferreira³

et al. 1999

J. Braz. Chem. Soc.

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No presente trabalho apresenta-se um método seletivo e sensível para rápida determinação de urânio usando o 2-(2-Tiazolilazo)-p-Cresol (TAC). O TAC reage com o urânio(VI) em pH 6,5 formando um complexo estável por pelo menos 3 h. Brometo de N-cetil-N,N,N-trimetil amônio (CTAB) e triton X-100 foram usados para aumento da sensibilidade e solubilidade do sistema respectivamente. O método permite a determinação de urânio na faixa de 0,30 a 12,0 µg mL -1 com absortividade molar estimada em 1,31 x 10 4 L mol -1 cm -1 e limite de detecção de 26 ng mL -1 em 588 nm. O uso do ácido 1,2-ciclohexilenodinitrilo tetraacético (CyDTA) como agente mascarante aumenta a seletividade do reagente para a determinação de urânio. O método proposto foi aplicado para determinação de urânio em água drenada de mina onde a precisão (R.S.D. < 2%) e exatidão obtidas foram satisfatórias.A sensitive and selective spectrophotometric method is proposed for the rapid determination of uranium using 2-(2-Thiazolylazo)-p-Cresol (TAC). The reaction between TAC and uranium (VI) is instantaneous at pH 6.5 and the absorbance remains stable for over 3 h. N-cetyl-N,N,N-trimethylamonium bromide (CTAB) and triton X-100 are used for increasing the sensitivity and solubility of the system respectively. The method allows the determination of uranium in the range from 0.30 to 12.0 µg mL -1 with a molar absorptivity of 1.31 x 10 4 L mol -1 cm -1 and features a detection limit of 26 ng mL -1 at 588 nm. The selectivity of the reagent was improved by the use of (1,2-cyclohexylenedinitrilo) tetraacetic acid (CyDTA) as masking agent. The proposed method has been successfully applied to the determination of uranium in mine drainage waters. The precision (R.S.D. < 2%) and the accuracy obtained were satisfactory.

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“…In our laboratory, it has been used for the spectrophotometric determination of nickel 14 , lead 15 , indium 16 , titanium 17 and vanadium; 18 it has also been proposed as a complexing agent in the separation processes for the determination of nickel 19 and iron 20 by using ICP-AES. This paper proposes an analytical procedure for the determination of trace cobalt in saline matrices by ICP-AES, using a column containing Amberlite XAD-2 resin loaded with TAC for preconcentration and separation.…”

Section: 12mentioning

confidence: 99%

Separation and Preconcentration of Cobalt after Sorption onto Amberlite XAD-2 Loaded with 2-(2-Thiazolylazo)-p-cresol

Ferreira

Brito

1999

ANAL. SCI.

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Analytical chemists frequently receive samples that cannot be analyzed in the natural state, due to the presence of interferences and/or inadequate sensibility of the available analytical methodology. Previous steps for separation and enrichment are almost always necessary, and many procedures have been proposed. The process, involving extraction in solid phase, has received more acceptance due to a number of possible advantages, including the availability and easy recovery of the solid phase, attainability of large preconcentration factors and the facility for separation and enrichment using systems with continuous flow. Besides, they usually do not need organic solvents, which may be toxic. For cobalt adsorption determination, several procedures have been proposed involving polyurethane foam 1 , activated carbon 2,3 , Amberlite XAD-4 resin 4,5 , naphthalene 6 and C 18 -bonded silica gel column; 7,8 other techniques as coprecipitation using indium hydroxide as colector 9 , liquid-liquid extraction 10 and cobalt separation as complex and filtration with a menbrane filter.

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2-(2-Thiazolylazo)-p-cresol as a spectrophotometric reagent for vanadium determination in the presence of ascorbic acid

Cited by 8 publications

References 16 publications

Complex formation in a liquid-liquid extraction-chromogenic system for vanadium(IV)

Complex formation in a liquid-liquid extraction-chromogenic system for vanadium(IV)

Spectrophotometric determination of uranium using 2-(2- Thiazolylazo)-p-Cresol (TAC) in the presence of surfactants

Separation and Preconcentration of Cobalt after Sorption onto Amberlite XAD-2 Loaded with 2-(2-Thiazolylazo)-p-cresol

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