Differential-pulse polarographic determination of molybdenum in steel

Lanza, Pietro; Ferri, Donatella; Buldini, Pier Luigi

doi:10.1039/an9800500379

Cited by 26 publications

(16 citation statements)

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“…18 Later, after establishing the optimum operating conditions for the method, the buffer pH was set to (2.1 ± 0.1), in order to obtain a nominal pH value as close as possible to (3.5 ± 0.1) after mixing the solvents and the reagents. Usually, under these conditions, no final pH adjustment is needed but, if required, it can be performed by using a few drops of a 0.1 mol L 21 HCl or NaOH solution. The eventual small changes in the solvent composition and concentrations caused by the addition of these drops do not change the results.…”

Section: Solutions and Reagentsmentioning

confidence: 99%

“…One of the most common separation procedures used in Mo determinations is liquid-liquid extraction with a-benzoinoxime (aBO), [11][12][13][14] which is often employed as a prior separation step in spectrophotometric methods for molybdenum determination. Several electroanalytical techniques have also been considered for this purpose, [15][16][17][18][19][20][21] due to their relatively lower complexity and lower detectability. These methods are usually run in aqueous solution or in a solution containing low concentrations of an organic solvent, added to dissolve non-soluble complexing agents whose metal complex will be the electroactive species to be detected.…”

Section: Introductionmentioning

confidence: 99%

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Determination of molybdenum in steel by adsorptive stripping voltammetry in a homogeneous ternary solvent system

Andrade

Almeida

Coscione

et al. 2001

Analyst

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A new alternative approach for the determination of molybdenum in steel is proposed, using adsorptive stripping voltammetry (AdSV). The determinations are performed in a homogeneous ternary solvent system (HTSS) composed of N,N-dimethylformamide, ethanol and water, with alpha-benzoinoxime (alpha BO) as the complexing agent and a sodium acetate-acetic acid buffer as the support electrolyte. The HTSS composition was optimized by mixture design modelling. The AdSV measurements were performed in the differential pulse mode using an accumulation potential of -1050 mV. Under these optimized experimental conditions, the Mo(VI)-alpha BO reduction current peak potential is observed at potentials near -1250 mV, much lower than those usually reported, and the calibration plot follows the polynomial equation I = 0.359 + 0.265 [CMo(VI)] - 0.015 [CMo(IV)]2 (r2 = 0.997), for Mo concentrations up to 10.0 micrograms L-1. There is a linear range in this calibration plot for Mo(VI) concentrations up to 0.20 microgram L-1, defined by the equation I = 0.353 + 0.385 [CMo(VI)] (r2 = 0.980). In both cases, I is the absolute value for the current in microA and CMo(VI) is the concentration of Mo in microgram L-1. The detection limit for this linear concentration range was estimated as 20 pg L-1. A RSD of 0.43% is associated with the signals at a Mo(VI) level of 0.72 microgram L-1. From the common method-interfering species tested, only iron at Fe/Mo(VI) ratios above 500 and vanadium and tungsten at M/Mo(VI) ratios above 100 appear to affect the analytical response significantly. Phosphorous may also reduce the analytical signal at P/Mo(VI) ratios above 100, due to the formation of the competitive P-Mo complex. The suggested routine procedure was tested by analyzing four stainless steel samples and the results compared well with the ICP-AES measurements. The higher sensitivity of this method permits direct determination of Mo(VI) in steels, eliminating the need of analyte concentration or separation steps in the sample processing procedure.

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Section: Solutions and Reagentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Determination of molybdenum in steel by adsorptive stripping voltammetry in a homogeneous ternary solvent system

Andrade

Almeida

Coscione

et al. 2001

Analyst

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“…Edmonds (26) determinó molibdeno (VI) por polarografía diferencial de impulsos en ácido nítrico 0,06 M como electrolito soporte; entre otras interferencias cita al titanio (IV) en concentración superior a 0,5 mg//. Lanza y otros (27) determinaron molibdeno en aceros utilizando como electrolito soporte nítrico-nitrato de amonio; la precisión fue del 5 %.…”

Section: Revision Bibliográficaunclassified

Determinación de trazas de Molibdeno (VI), Níquel (II) y Vanadio (V) en cementos por polarografía diferencial de impulsos

Cobo-Guzmán¹,

Gallego-Andreu²,

Gaspar-Tebar³

1985

Mater. construcc.

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Determinación de trazas de Molibdeno (VI),Níquel (II) y Vanadio (V) en cementos por polarografía diferencial de impulsos ANTONIO COBO-GUZMAN (*), RAFAEL GALLEGO-ANDREU (*) (+) y DEMETRIO GASPAR-TEBAR (**) RESUMEN En el presente trabajo se da cuenta de los resultados obtenidos cuando se aplica la polarograjia diferencial de impulsos a la determinación de los contenidos de compuestos a base de molibdeno (VI), níquel (II) y vanadio (V) en un cemento portland industrial; dichos contenidos se encuentran en cantidades del orden de p.p. m. En los estudios realizados se ha puesto de manifiesto que no es posible determinar simultáneamente el contenido de los tres iones mencionados en el cemento, pero que trabajando en medio ácido (clorhídrico o sulfúrico), en medio amoniacal o cianurado y en medio básico (producido por NaHCOj) se obtienen polarogramas que permiten realizar las mencionadas determinaciones cuantitativas de Mo (VI) en el primer medio, de Ni (II) en el segundo y de V (V) en el tercero.Gracias a la alta sensibilidad de la polarografía ha sido posible determinar la concentración de Ni (II) en el cemento estudiado, que se encuentra en cantidades comprendidas entre 2,9 y 3,4 p.p. m. (0,0002g y 0,00034 %' ^^ masa). 2.9 to 3.4 p.p.m. (0.0002g to 0.00034 %, in mass). SUMMARY In this work an account is given of the results obtained when the differential pulse polarography (differential pulse anodic stripping voltametry) is applied to the determination of the contents of the compounds by molybdenum (VI), nickel (II) and vanadium (V) in a common portland cement which are in quantities of the order of p.p. m. Those studies show that it is not possible to determine simultaneaously the content of the three mentioned ions in the cement, but if working in acid medium (hydrochloridric and sulphuric), in ammoniacal or cyanided medium and in basic medium (produced by NaHCOj) polagrogrammes are obtained which allow to complete those mentioned determinations of Mo (VI) in the first medium, of Ni (II) in the second and ofV(V) in the third. Because of the high sensibility of the polarography it is possible to determine the Ni (II) which is found in quantities from INTRODUCCIÓNLa polarografía diferencial de impulsos permite la determinación de trazas de determinados iones en concentración final 10"' M, lo que supone para la relación sólido/sólido, cantidades de p.p.m. En el presente artículo se aplica para determinar trazas de níquel (II), vanadio (V) y molibdeno (VI) en un cemento portland industrial.Esta técnica se ha usado anteriormente para determinar trazas de plomo, cobre, cadmio y cinc en CMC y bismuto en cobre (1).Deane (2) describe un procedimiento de electrólisis diferencial (polarografía diferencial de impulsos) para determinar los compuestos de talio en el polvo de los hornos de las fábricas de http://materconstrucc.revistas.csic.es cemento y en los óxidos de hierro. Los resultados obtenidos por medio de esta técnica y por espectrometría de llama son análogos, aun cuando por la primera se pueden dosificar cantidades ...

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“…Many electroanalytical procedures including anodic, cathodic [2], adsorptive and catalytic adsorptive stripping voltammetry [3][4][5][6][7][8][9][10][11][12][13][14] have been reported for the determination of trace amounts of molybdenum.…”

Section: Introductionmentioning

confidence: 99%

Trace determination of molybdenum by adsorptive cathodic stripping voltammetry

Hajian

Shams

2006

JICS

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Molybdenum is determined by adsorptive cathodic stripping voltammetry in 0.15 M nitric acid solution containing 15 μM 2',3,4',5,7-pentahydroxyflavone (morin) as a ligand. In this medium, molybdenum is preconcentrated on a hanging mercury drop electrode and stripped cathodically in square-wave voltammetry mode, with a peak potential of -350 mV vs. Ag/AgCl (saturated KCl). The effect of various parameters (ligand concentration, supporting electrolyte composition, accumulation potential and collection time) on the sensitivity and linear range of the calibration curve are discussed. With controlled accumulation for 1 min, the detection limit (3σ) was 0.45 ng ml -1 molybdenum and the calibration curve is linear up to 70 ng ml -1 . The procedure is applied to the determination of molybdenum in real samples with satisfactory results.

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Differential-pulse polarographic determination of molybdenum in steel

Cited by 26 publications

References 0 publications

Determination of molybdenum in steel by adsorptive stripping voltammetry in a homogeneous ternary solvent system

Determination of molybdenum in steel by adsorptive stripping voltammetry in a homogeneous ternary solvent system

Determinación de trazas de Molibdeno (VI), Níquel (II) y Vanadio (V) en cementos por polarografía diferencial de impulsos

Trace determination of molybdenum by adsorptive cathodic stripping voltammetry

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