Flow-injection spectrophotometric determination of molybdenum and vanadium with carminic acid in the presence of cetyltrimethylammonium bromide |
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Authors: | Tomás Pérez-Ruiz Carmen Martínez-Lozano Virginia Tomás Conceptión Paredes |
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Institution: | (1) Department of Analytical Chemistry, Faculty of Chemistry, University of Murcia, E-30071 Murcia, Spain |
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Abstract: | The color-forming reactions of molybdenum(VI) and vanadium(IV) with carminic acid (CA) in the presence of cetyltrimethylammonium bromide (CTAB) were used in the flow-injection determination of these metals. The micellar medium enhances the spectrophotometric features of the Mo(VI)-CA and V(IV)-CA binary complexes, and the higher solubility of these complexes when the CTAB concentration is above critical micelle concentration permits the easy application of flow-injection systems. Under the optimum conditions, linear calibration graphs were obtained from 0.76 to 28.8 g/ml for molybdenum and from 0.30 to 9.1 g/ml for vanadium. The detection limits were 0.33 and 0.16 g/ml for molybdenum and vanadium, respectively. The selectivity of the method was investigated and the procedure was successfully applied to the determination of molybdenum in steels and pharmaceuticals and of vanadium in petroleum products. |
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Keywords: | carminic acid molybdenum vanadium tensoactives CTAB spectrophotometry FIA |
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