Spectrophotometric determination of bismuth with alizarin red S and cetylpyridinium chloride : application to water samples, urine and veterinary preparation

Abstract EN

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 alizarin 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 maximum absorption at 507 nm with a molar absorptivity of 1.4 x 104 L.mol-1cm-1.

The calibration curve is linear in the concentration range 5–150 μg of bismuth (III) in a final volume of 20 ml (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 μg.mL-1, respectively.

Under optimum conditions, the stoichiometry of the reaction between bismuth (III), alizarin 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.