Determination of tungsten with pyrocatechol violet by first-derivative solid-phase spectrophotometry |
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Authors: | M I Pascual-Reguera A Molina-Diaz M C Pacheco-Castillo M C Anguita-Fernández M L Fernández-de Córdova L F Capitán-Vallvey |
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Institution: | (1) Department of Analytical Chemistry, Faculty of Experimental Sciences, University of Jaén, E-23071 Jaén, Spain;(2) Department of Analytical Chemistry, Faculty of Sciences, University of Granada, E-18071 Granada, Spain |
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Abstract: | Derivative spectrophotometry was applied to solid-phase spectrophotometry in order to enhance its sensitivity and remove the large background caused by the absorbance of the resin layer. Determination of micro-amounts of tungsten with pyrocatechol violet to form a 2 1 green complex in acid medium which is fixed on a dextran-type anion-exchange resin (Sephadex QAEA-25) is described as an example for the application of this technique. The absorbance of the resin packed in a 1-mm spectrophotometric cell, was measured directly. The characteristic peak amplitude of the signal at 674 nm in the first-derivative spectrum is useful for quantitative determination of tungsten (3–16 g 1–1; RSD 5.8%) in natural and industrial water samples. |
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Keywords: | solid-phase spectrophotometry derivative spectrophotometry pyrocatechol violet tungsten determination natural and industrial waters |
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