Search

CN-122016763-A - Three-dimensional enhanced SCGD-OES device and heavy metal detection method

CN122016763ACN 122016763 ACN122016763 ACN 122016763ACN-122016763-A

Abstract

The invention provides a three-dimensional enhanced SCGD-OES device and a heavy metal detection method, and relates to the technical field of spectrum detection and analysis. The multi-point discharge enhancement unit comprises at least two pairs of point discharge electrodes which are arranged in a space crossing way and are positioned below the main discharge channel and used for generating point discharge microplasma which is coupled with the space of the main discharge channel, so that a three-dimensional cooperative discharge area is formed near a solution interface. The three-dimensional structure expands the effective discharge area, enhances the interaction between the plasma and the solution, and improves the atomization and excitation efficiency of the analyte. The invention greatly improves the emission signal intensity and the detection sensitivity of heavy metal elements, has the detection limit as low as 0.06-1.90 mu g L ‑1 , has compact structure and good stability, and is suitable for on-site, rapid and multi-element simultaneous detection of trace heavy metals in complex samples such as environmental water samples, food and the like.

Inventors

  • YU YONGLIANG
  • SHEN HAO
  • LIU SHUANG

Assignees

  • 东北大学
  • 中国医科大学

Dates

Publication Date
20260512
Application Date
20260402

Claims (8)

  1. 1. The three-dimensional enhanced SCGD-OES device is characterized by comprising an excitation chamber, a power supply module, a tail gas leading-out channel, a sample leading-in module and an optical detection module; A solution cathode unit, a main discharge anode unit and a multipoint discharge enhancement unit are arranged in the excitation chamber; the solution cathode unit is used for containing and overflowing electrolyte solution to form a cathode; The main discharge anode unit and the solution cathode unit are oppositely arranged, and a main discharge gap is formed between the main discharge anode unit and the solution cathode unit and is used for generating a main discharge channel after being electrified; The multipoint discharge enhancement unit is arranged below the main discharge gap and is 0.5 mm away from an electrolyte solution interface of the solution cathode unit, and specifically comprises at least two pairs of point discharge electrodes which are arranged in a space crossing mode, and the point discharge electrodes are used for generating a plurality of point discharge microplasmas which are spatially coupled with the main discharge channel after being electrified, so that a three-dimensional cooperative discharge area is formed at the electrolyte solution interface distance of 0.5 mm; the power supply module is a high-voltage alternating current power supply and respectively supplies power to the main discharge anode unit and the multipoint discharge enhancement unit; The sample introducing module comprises a peristaltic pump and a sample container, wherein a liquid inlet of the peristaltic pump is communicated with the sample container through a pipeline, and a liquid outlet of the peristaltic pump is communicated with the solution cathode unit through a pipeline; The optical detection module comprises an optical fiber and a CCD spectrometer, wherein the collecting end of the optical fiber is aligned with a three-dimensional cooperative discharge area in the excitation chamber, and the emitted light signals are collected and transmitted to the CCD spectrometer; The tail gas guiding channel is communicated with the excitation chamber and is used for guiding out tail gas generated by discharge.
  2. 2. The three-dimensional enhanced SCGD-OES device according to claim 1, wherein the point discharge electrodes are arranged with their plane perpendicular to the axis of the main discharge gap and between the main discharge anode unit and the solution cathode unit.
  3. 3. The three-dimensional enhanced SCGD-OES device according to claim 2, wherein the main discharge anode unit is a tungsten needle electrode with a tip cone angle of 20 ° -40 °.
  4. 4. A three-dimensional enhanced SCGD-OES device according to claim 3 wherein the main discharge gap is 2.0mm-3.5mm.
  5. 5. The SCGD-OES device of claim 4, wherein the vertical distance between the discharge tip of the point discharge electrode and the main discharge anode unit is 1.5mm-3.0mm, and the distance between the two tips of the same point discharge electrode is 2.5mm-4.0mm.
  6. 6. The three-dimensional enhanced SCGD-OES device of claim 5, wherein the solution cathode unit includes a quartz capillary tube and a graphite tube coaxially disposed, the quartz capillary tube is coaxially inserted into the graphite tube, and an upper end of the quartz capillary tube protrudes from an upper edge of the graphite tube.
  7. 7. The heavy metal detection method is realized based on the three-dimensional enhanced SCGD-OES device and is characterized by comprising the following steps: Step 1, introducing a liquid sample to be tested into a solution cathode unit through a sample introduction module; Step 2, starting a power supply module, generating a main discharge channel between a main discharge anode unit and a solution cathode unit, and simultaneously generating point discharge microplasma between each point discharge electrode of a multi-point discharge enhancement unit, wherein the solution glow discharge microplasma and the point discharge microplasma are spatially coupled to form a three-dimensional cooperative discharge area; Step 3, collecting characteristic atomic emission spectrums emitted by elements to be detected in the three-dimensional cooperative discharge area by utilizing an optical detection module; and 4, quantitatively analyzing the concentration of the heavy metal element in the liquid sample to be detected according to the intensity of the characteristic atomic emission spectrum.
  8. 8. The method according to claim 7, wherein the heavy metal element includes at least one of cadmium Cd, zinc Zn, mercury Hg, and lead Pb.

Description

Three-dimensional enhanced SCGD-OES device and heavy metal detection method Technical Field The invention relates to the technical field of spectrum detection and analysis, in particular to a three-dimensional enhanced SCGD-OES device and a heavy metal detection method. Background The atomic emission spectroscopy (OES) has wide application in the fields of environmental pollution monitoring, food safety analysis and the like due to the advantages of rapid simultaneous detection and response of multiple elements. However, conventional Inductively Coupled Plasma (ICP) excitation sources are bulky, consume high power, require complex gas paths, and are difficult to meet the requirements of field portable analysis. OES technology driven by a microplasma excitation source, such as glow discharge, dielectric barrier discharge and the like, is an important development direction facing field multi-element analysis because the OES technology can operate in a compact and low-power consumption mode under normal pressure. Solution cathode glow discharge-atomic emission spectroscopy (SCGD-OES) is a typical system for achieving miniaturized atomic emission analysis of liquid samples, enabling direct analysis of liquid samples in a relatively simplified apparatus. However, conventional SCGD-OES are limited by low microplasma power and small excitation volume, resulting in insufficient amounts of analytes entering the discharge region and completing atomization and excitation, and their analytical sensitivity, particularly for trace heavy metals in complex matrix samples, remains difficult to meet the requirements of rapid screening on site. To increase the sensitivity of SCGD-OES, the prior art explores mainly from three aspects: (1) Sample system optimization, for example, adding a surfactant or an organic solvent (such as methanol, formic acid) to the sample to improve the volatilization and escape process of the target element; (2) Discharge conditions are regulated and controlled, for example, cooling electrodes, magnetic fields are applied, and the like, so that discharge stability and repeatability are improved; (3) The liquid morphology changes, for example by means of a continuous liquid surface, droplets or sprays, etc. changing the distribution of the solution in the vicinity of the discharge zone. However, under multi-element and complex matrix conditions, these methods have limitations in terms of stability and versatility of signal enhancement. In recent years, the distribution and energy action position of a discharge channel are regulated by changing a microplasma discharge structure, and the microplasma discharge structure has become an effective way for improving analysis performance. For example, in a gaseous excitation system of vapor generation or electrothermal evaporation sample injection, significant enhancement of signals has been achieved by adopting structural strategies such as hollow electrodes, cross double-point discharge, series discharge, and the like. However, for a liquid direct injection system, the conditions of a discharge medium and an electrode are obviously different from those of gaseous discharge, and the experience of related structures is difficult to directly transfer and apply. Therefore, development of a novel discharge structure suitable for direct liquid injection and capable of remarkably enhancing the excitation efficiency is needed. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a three-dimensional enhanced SCGD-OES device and a heavy metal detection method, the device introduces a plurality of pairs of point discharge microplasmas under a traditional SCGD main discharge channel, A three-dimensional discharge structure is constructed to solve the problems of low excitation efficiency and insufficient sensitivity of the existing SCGD-OES technology. In order to achieve the above purpose, the present invention provides the following technical solutions: in one aspect, the invention provides a three-dimensional enhanced SCGD-OES device, which comprises an excitation chamber, a power module, a tail gas leading-out channel, a sample leading-in module and an optical detection module; A solution cathode unit, a main discharge anode unit and a multipoint discharge enhancement unit are arranged in the excitation chamber; the solution cathode unit is used for containing and overflowing electrolyte solution to form a cathode; The main discharge anode unit and the solution cathode unit are oppositely arranged, and a main discharge gap is formed between the main discharge anode unit and the solution cathode unit and is used for generating a main discharge channel after being electrified; The multipoint discharge enhancement unit is arranged below the main discharge gap and is 0.5mm away from an electrolyte solution interface of the solution cathode unit, and specifically comprises at least two pairs of point discharge electrodes which are arran