Determination of trace arsenic using noble metal-free Ni2P/CdS composites for photochemical vapor generation for sample introduction into ICP-MS

Abstract

Determination of trace arsenic in complex matrices is crucial due to its toxicity, yet it remains a significant analytical challenge. Photochemical vapor generation (PVG) has emerged as an efficient alternative to conventional chemical vapor generation (CVG), offering superior sample introduction and matrix separation. Semiconductor nanomaterials and their composites are often used to enhance the efficiency of PVG. In this work, Ni₂P/CdS nanorod (NR) composites were synthesized via a one-step gas–solid phosphorylation process, with Ni₂P serving as a non-noble metal co-catalyst. The composites enabled efficient photochemical reduction of As(III) to arsine (AsH₃) under UV irradiation and its ultrasensitive detection using inductively coupled plasma mass spectrometry (ICP-MS), achieving an impressive limit of detection (LOD) of 3 ng L⁻¹ with a low concentration of formic acid. The method was successfully applied to the determination of trace As(III) in real water samples and certified reference materials. Additionally, the photocatalytic mechanism of the composites was investigated to elucidate their efficient photocatalytic performance. This work provides some new insights into designing advanced composite photocatalysts for PVG-based trace analysis.