High-sensitivity and field analysis of lead by portable optical emission spectrometry using a microplasma trap

Abstract

In this work, a novel field analysis method for analysing Pb in environmental water samples was developed using a portable optical emission spectrometric (OES) instrument coupled with solid acid hydride generation (HG) and a subsequent in situ dielectric barrier discharge (DBD) trap. Due to the DBD trapping and release processes, moisture interference generated from the HG process can be eliminated completely using carrier gas sweeping without the use of any desiccant. In addition, solid citric acid was first utilized to replace the commonly used HCl for HG in the determination of Pb, avoiding the inconvenient transportation problem of liquid acid for the field analysis. Under optimal conditions, a limit of detection (LOD) of 0.12 μg L⁻¹ was achieved for Pb, with a 3% relative standard deviation (RSD) at 20 μg L⁻¹ (n = 11). The proposed method was validated using simulated natural water certified reference materials (CRMs) and real environmental water samples. The obtained results of all CRMs are within their certified values; for real environmental water samples, the recoveries were 94–111% vs. the ICP-MS method. With advantages of small size (0.6 m × 0.5 m × 0.3 m), low manufacturing cost, high sensitivity and low energy consumption (<60 W), the proposed method is especially suitable for the field analysis of Pb in environmental water and has the potential for the simultaneous analysis of more elements.