Ultrasonic Nebulization-Accelerated Gas-Phase Enrichment Following In Situ Microplasma Desorption for Analysis of Trace Heavy Metals by Optical Emission Spectrometry.

ABSTRACT

Despite the great potential of microplasma optical emission spectrometry (OES) for on-site analysis, it remains a challenge to achieve the fast, sensitive, batch, and multielement analysis of trace heavy metals in a complex matrix. Herein, a novel ultrasonic nebulization-accelerated gas-phase enrichment (GPE) following in situ microplasma desorption sampling approach is employed for the determination of trace heavy metals by a miniature dielectric barrier discharge (DBD)-OES device. The volatile heavy metal species obtained by hydride generation (HG) can be quickly separated from the complex matrix under the action of ultrasonic nebulization, adsorbed on the surface of the activated carbon electrode tip for GPE, and then in situ desorbed and excited by DBD microplasma to achieve multielement OES analysis. With an array nebulizer plate, a batch of 10 samples can be handled for GPE in 40 s, and DBD-OES analysis is maintained at a rate of 6 s per sample. Under the optimized conditions, the detection limits for simultaneous determinations of Hg, Cd, Cu, and Sn are 0.005, 0.01, 0.03, and 0.04 µg L-1, respectively, and the detection sensitivities are about 164, 157, 132, and 91-fold improved with respect to those of the conventional HG-DBD-OES mode, respectively. The accuracy and practicability are verified by measuring several certified reference materials. This fast GPE plus in situ DBD-OES analysis strategy possesses the features of simple operation, time-savings, and low cost, contributing to volatile species transport, matrix interference elimination, and device miniaturization for field applications.