A novel, compact, and green method was developed for the determination and speciation analysis of mercury, based on flow injection photochemical vapor generation (PVG) coupled with miniaturized solution cathode glow discharge-atomic emission spectroscopy (SCGD-AES). The SCGD was generated between a miniature hollow titanium tube and a solution emerging from a glass capillary. Cold mercury vapor (Hg(0)) was generated by PVG and subsequently delivered to the SCGD for excitation, and finally the emission signals were recorded by a miniaturized spectrograph. The detection limits (DLs) of Hg(II) and methylmercury (MeHg) were both determined to be 0.2 μg L. Moreover, mercury speciation analysis could also be performed by using different wavelengths and powers from the UV lamp and irradiation times. Both Hg(II) and MeHg can be converted to Hg(0) for the determination of total mercury (T-Hg) with 8 W/254 nm UV lamp and 60 s irradiation time; while only Hg(II) can be reduced to Hg(0) and determined selectively with 4 W/365 nm UV lamp and 20 s irradiation time. Then, the concentration of MeHg can be calculated by subtracting the Hg(II) from the T-Hg. Because of its similar sensitivity and DL at 8 W/254 nm, the simpler and less toxic Hg(II) was used successfully as a primary standard for the quantification of T-Hg. The novel PVG-SCGD-AES system provides not only a 365-fold improvement in the DL for Hg(II) but also a nonchromatographic method for the speciation analysis of mercury. After validating its accuracy, this method was successfully used for mercury speciation analysis of water and biological samples.
We herein describe a novel method of hydride generation (HG) coupled to a newly designed atmospheric pressure solution-cathode glow discharge (SCGD) spectrometric technique for the ultratrace determination of tin, germanium, and selenium. In this novel SCGD process, gas introduction was permitted using a hollow titanium tube as both the anode and sampling port. In these experiments, the analytes were converted into volatile hydrides upon passing through the hydride generator, and were introduced into the near-anode region of the SCGD system, where they were detected directly by atomic emission spectrometry (AES). A significant improvement in both selectivity and sensitivity was achieved, which was reflected in an improvement in the detection limits (DLs) by 3 orders of magnitude, in addition to successful valence analysis of Se without the requirement for chromatographic separation. In the absence of a strict sample pretreatment process and with a reduction in electrolyte consumption, the detection limits of Sn, Ge, and Se were determined to be 0.8, 0.5, and 0.2 μg·L. Moreover, our HG-SCGD-AES system demonstrated excellent repeatability (<3% peak height relative standard deviation) and more than 2 orders of linear dynamic range. The optimal operating conditions are outlined herein, and the analytical performance of the system is evaluated as described. Furthermore, our method was applied for the analysis of Sn, Ge, and Se in both environmental and biological samples, and the obtained results were in good agreement with reference values.
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