Rapid determination of arsenic in the presence of lead in a zinc sulphide matrix by X-ray fluorescence spectrometry

Abstract

A direct calibration X-ray fluorescence method has been developed for the determination of arsenic in a zinc sulphide matrix applicable to concentrations over 60 µg g^–1(4 × detection limit) in the presence of lead concentrations between 0.024 and 1.0%m/m in pelleted specimens. The heavy nature of the zinc sulphide matrix allows inter-element effects to be minimised. The proposed method utilises a previously determined factor to correct for the interference of the Pb Lα peak (33.93 °2θ) at the As Kα peak (34.00 °2θ). This factor is determined with the aid of a standard containing only lead and is defined as the ratio of the fluorescence intensities of the As Kα and Pb L_γ1(24.07 °2θ) peaks. It is recommended that the chemical state of the lead compounds be the same in standards and samples.