Determination of Trace Boron in Iron and Steel by Adsorptive Stripping Voltammetry using Beryllon III

Abstract

Adsorptive stripping voltammetry is proposed for determination of boron at low μg g⁻¹ level in iron and steel. Beryllon III was used as a complexing agent for boron(III). Optimum conditions for the formation of the boron(III)–Beryllon III complex were as follows: 0.06 M nitrate–0.04 M sulfate supporting electrolyte at pH 4.5; 1.0×10⁻⁵ M Beryllon III; 24 h complexation time. The complex was accumulated on a hanging mercury drop electrode at −0.35 V vs. SCE for 60 s under stirring, and was subsequently cathodically stripped to −0.8 V vs. SCE at a scan rate of 10 mV s⁻¹ using a differential pulse mode. Interference by iron(III) was eliminated by the complexation with metaphosphoric acid. After cathodic stripping, a single well-defined peak was observed at around −0.5 V vs. SCE. The influence of foreign elements on the determination was also evaluated. The calibration graph (peak height vs. boron(III) concentration) in the presence of 1 mg mL⁻¹ iron(III) was linear over a concentration range of 1–25 ng mL⁻¹ (correlation coefficient >0.999), with a relative standard deviation (n=4) of 2.6% at 10 ng mL⁻¹. The minimum limit of determination was 1 μg g⁻¹ of boron in iron and steel. The proposed method has been proved to be applicable to the determination of trace boron in iron and steel with good precision and accuracy.