Abstract
A simple , sensitive and accurate spectrophotometric method for the trace determination of bismuth (III) has been developed .This method is based on the reaction of bismuth (III) with arsenazo(III) in acid solution (pH=1.9) to form a blue water soluble complex which exhibits maximum absorption at 612nm .Beer's law is obeyed over the concentration range of 2-85 ?g bismuth (III) in a final volume of 20 mL( i.e. 0.1 – 4.25?g.mL-1) with a correlation coefficient of (0.9981) and molar absorptivity 1.9×104 L.mol-1.cm-1 . The limit of detection (LOD) and the limit of quantification (LOQ) are 0.0633 and 0.0847 ?g.mL-1 , respectively . Under optimum conditions,the stoichiometry of the reaction between bismuth (III) and arsenazo(III) reagent was found to be 1:2. The recoveries were obtained in the range of 98.9 - 100.0% and a relative standard deviation of ±0.59 to ±2.73% depending on the concentration level of bismuth. The effect of interferences by a number of common cations and anions in the presence of composite mixture has been studied .The proposed method has been applied successfully for determination of bismuth in water samples and veterinary preparation .
Highlights
A simple, sensitive and accurate spectrophotometric method for the trace determination of bismuth (III) has been developed .This method is based on the reaction of bismuth (III) with arsenazo(III) in acid solution to form a blue water soluble complex which exhibits maximum absorption at 612nm .Beer's law is obeyed over the concentration range of 2-85 g bismuth (III) in a final volume of 20 mL( i.e. 0.1 – 4.25 g.mL-1) with a correlation coefficient of (0.9981) and molar absorptivity 1.9×104 L.mol-1.cm-1
The preliminary investigation showed that on mixing 50 μg/20 mL of bismuth (III) with excess of 5x10-4M Arsenazo III (AZIII) reagent and distilled water in volumetric flask a blue binary water soluble complex [ Bi(III)-AZIII ] was observed and showed a maximum absorption at 613nm against the corresponding reagent blank solution. This observation led us to the development of a sensitive method for determination of bismuth based on a binary complex formation
Effect of pH The effect of pH on the colour intensity of [Bi(III)-AZIII ] complex is investigated by adding different amounts of 0.1M HNO3 and 0.1M NaOH solutions .The complex is showed pH dependent absorption maximum at 612 nm, whereas the reagent blank solution showed maximum absorption at 534 nm
Summary
A simple , sensitive and accurate spectrophotometric method for the trace determination of bismuth (III) has been developed .This method is based on the reaction of bismuth (III) with arsenazo(III) in acid solution (pH=1.9) to form a blue water soluble complex which exhibits maximum absorption at 612nm .Beer's law is obeyed over the concentration range of 2-85 g bismuth (III) in a final volume of 20 mL( i.e. 0.1 – 4.25 g.mL-1) with a correlation coefficient of (0.9981) and molar absorptivity 1.9×104 L.mol-1.cm-1. AZIII as a chelating agent for determination of bismuth(III) in water samples and veterinary preparation. Stock bismuth (III) solution (1000 μg.mL-1) : It is prepared by dissolving 0.2312g of Bi (NO3) 3.5H2O (Fluka) in 3mL of 5M nitric acid and diluted to the mark with distilled water in a 100 mL volumetric flask [7] .
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