Centri-voltammetric determination of molybdenum

Abstract

Centri-voltammetry is a method developed in the last decade which combines the advantages of centrifugation and voltammetry and hence provides a practical way for application of co-precipitation in trace analysis allowing direct voltammetric scan. The present study describes another application of the centri-voltammetric method for the determination of biologically essential trace elements, in particular, molybdenum ion. For this purpose, a dual-functional voltammetric cell adjustable to the centrifuge was designed and utilized in the determination of molybdenum ions with various carrier reagents, i.e. oxine, pyrogallol red, and cupferron. Optimization studies include solution properties as well as voltammetric measurement and centrifugal parameters. Among the reagents studied, the best results were obtained with pyrogallol red and the reduction peak current of the complex was utilized for analytical purposes. The limit of detection from calibration curves was calculated to be 9.4 × 10⁻⁹ M and a better sensitivity was obtained in the presence of chlorate ions that are known to have a catalytic effect on the reaction. The method was employed in the determination of molybdenum in milk samples and the results were compared with those obtained by the ICP-MS method.