Key Laboratory of Green Chemistry & Technology of MOE, College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, China.
West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu, Sichuan 610064, China.
Anal Chem. 2021 Jun 15;93(23):8257-8264. doi: 10.1021/acs.analchem.1c01091. Epub 2021 Jun 2.
Despite increased interest in microplasma-induced vapor generation (μPIVG) over the past several years, applications in real sample analyses remain limited due to their relatively low vapor generation efficiency and ambiguous mechanism. In this work, a novel method using methanol for significantly enhancing the liquid electrode discharge μPIVG efficiency was developed for the simultaneous and sensitive determination of Hg, Cd, and Zn by atomic fluorescence spectrometry (AFS). It is worth noting that the possible enhancement mechanism was investigated the characterizations of volatile products by AFS, microplasma optical emission spectrometry, online gas chromatography, and gas chromatography-mass spectrometry, which involved the reductive species such as electrons, hydrogen radicals (·H), methyl radicals (·CH), and other intermediates in the argon plasma adding methanol. Under the optimized conditions, the limits of detection of 0.007, 0.05, and 0.5 μg L were obtained for Hg, Cd, and Zn, respectively, with relative standard deviations of 3.1, 3.7, and 5.2% for these elements, respectively. Vapor generation efficiencies of 90, 83, and 55% were achieved for Hg, Cd, and Zn, respectively, and improved 2.7-, 4.8-, and 7.9-fold, respectively, compared to those obtained in the absence of methanol. The accuracy and practicability of the proposed method were validated by the determination of Hg, Cd, and Zn in a certified reference material (CRM, Lobster hepatopancreas, TORT-3) and crayfish samples collected from three different provinces of China.
尽管近年来人们对微等离子体诱导蒸汽发生（μPIVG）越来越感兴趣，但由于其蒸汽发生效率相对较低且机制不明确，实际样品分析中的应用仍然有限。在这项工作中，开发了一种使用甲醇显著提高液体电极放电μPIVG 效率的新方法，用于通过原子荧光光谱法（AFS）同时灵敏地测定汞，镉和锌。值得注意的是，通过 AFS，微等离子体发射光谱法，在线气相色谱法和气相色谱-质谱法研究了挥发性产物的特征，研究了甲醇添加到氩等离子体中的可能增强机制，涉及电子，氢自由基（·H），甲基自由基（·CH）和其他中间产物等还原物质。在优化条件下，Hg，Cd 和 Zn 的检出限分别为 0.007、0.05 和 0.5μg·L，相应元素的相对标准偏差分别为 3.1%、3.7%和 5.2%。Hg、Cd 和 Zn 的蒸汽发生效率分别达到 90%、83%和 55%，与没有甲醇时相比，分别提高了 2.7 倍、4.8 倍和 7.9 倍。通过测定中国三个不同省份采集的螯虾样品和贝类中的认证参考物质（CRM，龙虾肝胰腺，TORT-3）中的 Hg，Cd 和 Zn，验证了所提出方法的准确性和实用性。
