Voltammetric sensing of thallium at a carbon paste electrode modified with a crown ether

Abstract

We describe a new method for differential-pulse anodic stripping voltammetric determination of thallium(I) using a carbon paste electrode modified with dicyclohexyl-18-crown-6. The effect of supporting electrolyte (type and pH), accumulation and reduction potential, and of time and amount of modifier were investigated by differential pulse anodic stripping voltammetry. A method was then worked out for the determination of thallium at low levels. Under optimized conditions, the response to Tl(I) is linear in the range from 3.0 to 250 ng mL−1. The detection limit is 0.86 ng mL−1. The sensor displays good repeatability (with a relative standard deviation of ±2.70 % for n = 7) and was applied to the determination of Tl(I) in water, hair samples, and certified reference materials.