Research Center for Analytical Sciences, Department of Chemistry, College of Sciences, Northeastern University, P.O. Box 332, Shenyang 110819, China.
Anal Chem. 2021 Apr 20;93(15):6262-6269. doi: 10.1021/acs.analchem.1c00819. Epub 2021 Apr 7.
The miniaturized optical emission spectrometry (OES) devices based on various microplasma excitation sources provide reliable tools for on-site analysis of heavy metal pollution, while the development of convenient and efficient sample introduction approaches is essential to improve their performances for field analysis. Herein, a small activated carbon electrode tip is employed as solid support to preconcentrate heavy metals in water and subsequently served as an inner electrode of the coaxial dielectric barrier discharge (DBD) to generate microplasma. In this case, heavy metal analytes in water are first adsorbed on the surface of the activated carbon electrode tip via a simple liquid-solid phase transformation during the sample loading process, and then, fast released to produce OES during the DBD microplasma excitation process. The corresponding OES signals are synchronously recorded by a charge-coupled device (CCD) spectrometer for quantitative analysis. This activated carbon electrode tip provides a new tool for sample introduction into the DBD microplasma and facilitates "insert-and-go" in subsequent DBD-OES analysis. With a multiplexed activated carbon electrode tip array, a batch of water samples (50 mL) can be loaded in parallel within 5 min. After drying the activated carbon electrode tips for 5 min, the DBD-OES analysis is maintained at a rate of 6 s per sample. Under the optimized conditions, the detection limits of 0.03 and 0.6 μg L are obtained for Cd and Pb, respectively. The accuracy and practicability of the present DBD-OES system have been verified by measuring several certified reference materials and real water samples. This analytical strategy not only simplifies the sample pretreatment steps but also significantly improves the sensitivity of the DBD-OES system for heavy metal detection. By virtue of the advantages of high sensitivity, fast analysis speed, simple operation, low cost, and favorable portability, the upgraded DBD-OES system provides a more powerful tool for on-site analysis of heavy metal pollution.
基于各种微等离子体激发源的微型化发射光谱 (OES) 设备为现场分析重金属污染提供了可靠的工具，而开发方便、高效的样品引入方法对于提高其现场分析性能至关重要。在此，采用小型活性炭电极尖端作为固体支撑物，用于预浓缩水中的重金属，随后将其用作同轴介质阻挡放电 (DBD) 的内电极以产生微等离子体。在这种情况下，水中的重金属分析物首先在样品加载过程中通过简单的液-固相间转变被吸附在活性炭电极尖端的表面上，然后在 DBD 微等离子体激发过程中快速释放以产生 OES。通过电荷耦合器件 (CCD) 光谱仪同步记录相应的 OES 信号，用于定量分析。这种活性炭电极尖端为将样品引入 DBD 微等离子体提供了一种新工具，并便于在随后的 DBD-OES 分析中“插入即用”。采用多路复用的活性炭电极尖端阵列，可以在 5 分钟内同时加载 50 mL 的一批水样。在将活性炭电极尖端干燥 5 分钟后，以 6 s 每个样品的速度维持 DBD-OES 分析。在优化条件下，分别获得了 Cd 和 Pb 的检测限为 0.03 和 0.6 μg L。通过测量几种认证参考材料和实际水样，验证了本 DBD-OES 系统的准确性和实用性。这种分析策略不仅简化了样品预处理步骤，而且显著提高了 DBD-OES 系统对重金属检测的灵敏度。凭借高灵敏度、快速分析速度、操作简单、成本低和良好的便携性等优势，升级后的 DBD-OES 系统为现场分析重金属污染提供了更强大的工具。
