Elemental determination of microsamples by liquid film dielectric barrier discharge atomic emission spectrometry.
Elemental determination of microsamples by liquid film dielectric barrier discharge atomic emission spectrometry.
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DOI：
10.1021/ac300518y
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发表时间：
2012-04
影响因子：
7.4
通讯作者：
Qian He;Zhenli Zhu;Shenghong Hu;Hongtao Zheng;Lanlan Jin
中科院分区：
文献类型：
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作者：
Qian He;Zhenli Zhu;Shenghong Hu;Hongtao Zheng;Lanlan Jin
本文研制了一种新型的液膜介质阻挡放电（LFDBD）原子发射源，用于微量样品的元素测定。它由铜电极、钨丝电极和介于两者之间的一块玻璃片组成，玻璃片既充当介质屏障，又充当样品板。含有1 mol L（-1）硝酸的样品溶液，当沉积在玻片表面时，形成一层薄薄的液体膜。当交流高压（峰值电压3.7 kV，频率30 kHz）作用于钨丝电极时，在电极尖端与液膜表面之间产生等离子体。样品溶液中的金属离子通过等离子体原子发射测量实现了定性和定量测定，并在本研究中用元素Na、K、Cu、Zn和Cd进行了验证。Na的检出限为0.6 ng (7 μg L(-1))， Zn的检出限为6 ng （79 μg L(-1)）。重复性，表示为相对标准偏差，从7个重复分析的样品，分析物浓度为1 mg L(-1)，从2.1%到4.4%不等。与其他在大气压下运行的液体排出系统相比，目前的系统具有以下几个优点：首先，它消除了样品流系统（例如注射器或蠕动泵）的使用；相反，一小部分样品被直接移到载玻片上进行分析。其次，它是一个微量分析系统，需要的样品体积≤80 μL，当样品数量有限时，这是一个优势。第三，由于样品是等分的，没有冲洗时间，分析可以很容易地扩展到样品阵列进行高通量分析。由于其简单、经济、低功耗和不需要惰性气体，LFDBD有望用于现场元素测定。
In this study, a new liquid-film dielectric barrier discharge (LFDBD) atomic emission source was developed for microsample elemental determination. It consists of a copper electrode, a tungsten wire electrode, and a piece of glass slide between them, which serves as the dielectric barrier as well as the sample plate. The sample solution with 1 mol L(-1) nitric acid, when deposited onto the surface of the glass slide, forms a thin liquid film. The plasma is generated between the tip of the tungsten wire electrode and the liquid film surface when alternating-current (ac) high voltage (peak voltage ~3.7 kV, frequency ~30 kHz) is applied on the electrodes. Qualitative and quantitative determinations of metal ions in the sample solution were achieved by atomic emission measurements in the plasma and were demonstrated in this study with elements Na, K, Cu, Zn, and Cd. Detection limits were in the range from 0.6 ng (7 μg L(-1)) for Na to 6 ng (79 μg L(-1)) for Zn. Repeatability, expressed as relative standard deviation from seven repetitive analyses of samples with analyte concentrations at 1 mg L(-1), varied from 2.1% to 4.4%. Compared with other liquid discharge systems that operate at atmospheric pressure, the current system offers several advantages: First, it eliminates the use of a sample flow system (e.g., syringe or peristaltic pump); instead, a small aliquot of sample is directly pipetted onto the glass slide for analysis. Second, it is a microanalysis system and requires sample volume ≤80 μL, a benefit when a limited amount of sample is available. Third, because the sample is applied in aliquot, there is no washout time, and the analysis can be easily extended to sample array for high-throughput analysis. The proposed LFDBD is promising for in-field elemental determination because of its simplicity, cost effectiveness, low power supply, and no inert gas requirement.