Spectrophotometric Determination of Bismuth with Alizarine Red S and Cetylpyridinium Chloride - Application to Water Samples, Urine and Veterinary Preparation

Salim A Mohammed,Mohammed M Mohammed

doi:10.33899/rjs.2013.78759

Abstract

A simple, accurate, sensitive and reliable method for spectrophotometric determination of Bismuth(III) is developed. The method is based on the reaction of bismuth (III) with alizarine red S (ARS) and cetylpyridinium chloride (CPC) in the presence of Triton X-100 at pH 3 to form a pink, water soluble ternary complex which shows a maximum absorption at 507 nm with a molar absorptivity of 1.4 x104 L.mol-1cm-1. The calibration curve is linear in the concentration range 5– 150 μg of bismuth (III) in a final volume of 20mL (i.e. 0.25-7.5 μg mL-1) with a determination coefficient of (R2) (0.9974). The limit of detection (LOD) and the limit of quantification (LOQ) are 0.0671 and 0.2235 g.mL-1, respectively. Under optimum conditions, the stoichiometry of the reaction between bismuth (III), alizarine red S and cetylpyridinium chloride is found to be 1:3:6, respectively. The recoveries are obtained in the range of 98.8- 102.1% and a relative standard deviation (RSD) of ± 0.93 to ±3.07% depending on the concentration level. The proposed method has been applied successfully to the determination of bismuth (III) in various samples such as, natural waters, urine and veterinary preparation

Highlights

A simple, accurate, sensitive and reliable method for spectrophotometric determination of Bismuth(III) is developed
The preliminary investigation showed that on mixing 100 μg of bismuth (III) with excess of 1×10-3M alizarin red S (ARS) reagent,1 ml of 1x10-3M cetylpyridinium chloride (CPC) solution, 2 ml of 1% Triton X-100 solution and distilled water in a 20-ml calibrated flask, a red ternary water soluble complex [Bi(III)-ARS-CPC] is observed and showed a maximum absorption at 501 nm against the corresponding reagent blank solution. This observation led us to the development of a sensitive method for the determination of bismuth based on a ternary complex formation
The results listed in Table (1) show that 5 ml of 1x10-3M CPC and 0.5 ml of 1% Triton X-100 solutions have been considered the optimum amounts and used for the subsequent experiments for the following: ( i ) turbidity of solution was disappeared and (ii) the colour contrast of the Bi(III)-ARS reaction is improved

Summary

INTRODUCTION

Bismuth is found in the earth's crust up to 0.0002%. It is widely used in the form of oxides, carbonates and sulfides in nature (Didi et al, 2011). This solution is prepared by dissolving 0.2312 g of Bi (NO3) 3.5H2O (Fluka) in 3 ml of 5 M nitric acid and diluted to the mark with distilled water in a 100-ml volumetric flask. A suitable aliquot containing 5 – 200 μg of Bi(III) was transferred into 20-ml calibrated flask and mixed with 2 ml of 1×10-3M ARS reagent, 5 ml of 1x10-3M CPC solution, 1 ml of buffer solution pH 3, 2 ml of composite mixture solution and 0.5 ml of 1% Triton x-100 solution. A quantity of powder equivalent to 0.01 g of bismuth is weighed and dissolved in 10 ml of 2.5 M nitric acid The solution is shaken thoroughly, filtered and diluted with distilled water to 100 ml in a volumetric flask. An aliquot of the diluted drug solution is treated as done in the recommended procedure

RESULTS AND DISCUSSION

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CONCLUSION