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Electrochemical pre-reduction method and device for mercury speciation analysis by HPLC-AFS (high performance liquid chromatography and atomic fluorescence spectroscopy)

A HPLC-AFS, speciation analysis technology, applied in electrochemical variables of materials, measuring devices, analytical materials, etc., can solve the problems of low detection limit of organic mercury, low analysis efficiency, low efficiency of ultraviolet digestion, etc., and achieve the detection limit obvious effect

Inactive Publication Date: 2015-11-25
BEIJING CENT FOR PHYSICAL & CHEM ANALYSIS
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  • Abstract
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Problems solved by technology

[0003] The UV digestion efficiency of the existing technology (HPLC-UV-CV-AFS) is still low for organic mercury, resulting in a low detection limit of organic mercury, and the CV technology still needs an unstable reducing agent such as potassium borohydride. While the purity requirement is high, it also needs to be ready-to-use and ready-to-use, and the analysis efficiency is low

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  • Electrochemical pre-reduction method and device for mercury speciation analysis by HPLC-AFS (high performance liquid chromatography and atomic fluorescence spectroscopy)
  • Electrochemical pre-reduction method and device for mercury speciation analysis by HPLC-AFS (high performance liquid chromatography and atomic fluorescence spectroscopy)
  • Electrochemical pre-reduction method and device for mercury speciation analysis by HPLC-AFS (high performance liquid chromatography and atomic fluorescence spectroscopy)

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Experimental program
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Effect test

Embodiment 1

[0037] Such as figure 1 with figure 2 , an electrochemical pre-reduction device for HPLC-AFS mercury speciation analysis, which is connected with the outflow pipeline of C18 high performance liquid chromatography column (ZORBAXXDB-C18 column), and this electrochemical pre-reduction device is made of PTFE matrix 21, silicon An electrochemical flow cell assembled from a rubber sheet 16 and an ion-exchange membrane 10 (Nafion membrane), specifically including PTFE anode substrates and cathode substrates with the same shape, an ion-exchange membrane 10 is arranged between the anode substrate and the cathode substrate, and the ion-exchange membrane An anode gasket made of silicon rubber sheet 16 is placed between 10 and the anode substrate, and a rectangular hole is opened in the middle of the silicon rubber sheet 16 to form an anode chamber; an anode gasket is placed between the ion exchange membrane 10 and the cathode substrate, and the middle of the gasket is The opening const...

Embodiment 2

[0042] The influence of embodiment 2 electrolytic current on sensitivity

[0043] If the electrolytic current is too small, it is not conducive to the electrolysis of different forms of mercury into atomic states, which will reduce the steam generation efficiency of mercury; if the electrolytic current is too large, a large amount of hydrogen gas will be generated in the cathode chamber, and if the hydrogen gas production is too large, it will affect the stability of the detection device, making the Measurement deviations increase and at the same time there is a possibility of overheating of the electrolytic cell. This embodiment adopts the device of embodiment 1, HPLC mobile phase: 3% acetonitrile + 0.5% ammonium acetate + 0.03% 2-mercaptoethanol, the influence of the current on the sensitivity in the range of 0.3 ~ 1.5A electrolysis current is investigated, Fig. 7 (a), (b) are 2ppb inorganic mercury (Hg 2+ ) 6 measurements and standard curves under different currents, Figur...

Embodiment 3

[0045] Embodiment 3 Electrolyte flow rate optimization

[0046] Choose 0.5mol.L -1 Sulfuric acid is used as the supporting electrolyte solution of the anode and cathode, and the 0.005-0.012m.s -1 The relationship between the fluorescence intensity of 2 μg / L methylmercury and the flow rate of the electrolyte solution within the flow rate range. The test device is as in Example 1, and the electrolytic current density is 0.54A / cm 2 . HPLC mobile phase: 5% methanol 0.5% ammonium acetate + 0.03% 2-mercaptoethanol. As shown in Fig. 5(a), within the tested concentration range, the fluorescence intensity decreases with the increase of electrolyte flow rate.

[0047] On the one hand, under a certain injection volume, the increase of the flow rate of the electrolyte solution is conducive to the mass transfer process of the sample to the electrode surface, and at the same time accelerates the rate of electrolysis products detaching from the electrode surface. This is conducive to th...

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Abstract

The invention provides an electrochemical pre-reduction method for mercury speciation analysis by HPLC-AFS (high performance liquid chromatography and atomic fluorescence spectroscopy). The method includes the steps of 1, introducing a mercury-containing sample into a high performance liquid chromatographic column, and separating different forms of mercury according to different retention times; 2, delivering the separated mercury into a cathode chamber of an electrochemical flow cell by a peristaltic pump, and reducing the mercury into mercury vapor by electrolysis; 3, subjecting the mercury vapor to gas-liquid separation in a gas-liquid separator, and carrying an atomizer of an atomic fluorescence spectrophotometer by carrier argon to allow quantitative analysis of the different forms of mercury. Compared with the prior HPLC-UV-CV-AFS technique, the HPLC-EcVG-AFS has especially significant advantages in terms of sensitivity and detection limit, the detection limit for organic forms of mercury is about 1 lower than that of the HPLC-UV-CV-AFS technique, and a relative standard deviation is less than 5%; meanwhile, the method needs no reducing agents such as potassium borohydride, and dependence on reagent purity and stability is gotten rid of.

Description

technical field [0001] The invention belongs to the field of analysis by means of spectrum, and in particular relates to a reduction method and a device used for atomic fluorescence spectrum analysis. Background technique [0002] The toxicity of different forms of mercury varies greatly, so the speciation analysis of mercury is of great significance. High performance liquid chromatography-atomic fluorescence spectrometry (HPLC-AFS) is a commonly used method for mercury speciation analysis. This technology uses HPLC separation technology to separate inorganic mercury (Hg 2+ ), methylmercury (HgCH 3 + ), ethylmercury (HgC 2 h 5 + ), phenyl mercury (HgC 6 h 5 + ) and other four conventional mercury species were separated and then detected by AFS technology. Conventional AFS technology adopts chemical method cold vapor generation (cold vapor generation, CV method) to atomize mercury element through chemical reduction of potassium borohydride-acid system, but the atomi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N30/88G01N27/28G01N21/64
Inventor 祖文川汪雨汪正浩武彦文
Owner BEIJING CENT FOR PHYSICAL & CHEM ANALYSIS
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