CN112986219B - Electrode sampling DBD microplasma atomic emission spectrometry detection system and method - Google Patents

Abstract

An electrode sample introduction DBD micro plasma atomic emission spectrum detection system and method belong to the field of atomic emission spectrum detection equipment and analysis. The detection system comprises a DBD microplasma excitation source and a spectrum detection system; a sample electrode in the DBD micro-plasma excitation source is used for enriching an object to be measured; one end of the sample electrode, which is enriched with the object to be detected, is inserted into the tube of the quartz tube; the output end of the neon lamp power supply connected with the voltage regulator is respectively connected with the high-voltage lead and one end of the sample electrode, which is not enriched with the object to be measured; the branch pipe arranged on the quartz tube is connected with the air circuit system; the spectrum detection system comprises a lens, an optical fiber and a micro spectrometer, wherein the lens is connected with the micro spectrometer through the optical fiber. The method comprises the following steps: the sample solution containing the analyte is pre-concentrated by flowing it over the surface of the sample electrode at a constant flow rate by means of a peristaltic pump, dried, and then measured. The system and the method can analyze the object to be detected adsorbed on the surface of the electrode in situ, and are very suitable for the rapid high-throughput analysis of batch samples.

Description

Electrode sampling DBD microplasma atomic emission spectrometry detection system and method

technical field

The invention belongs to the technical field of atomic emission spectrum detection equipment and analysis, and in particular relates to an electrode sampling DBD microplasma atomic emission spectrum detection system and method.

Background technique

Atomic emission spectrometry is a very commonly used analytical technique for element content detection in scientific fields such as food and environment, and is also an important means of ecological construction and environmental protection. Large-scale spectral analysis instruments in the laboratory can achieve stable, accurate and highly sensitive detection of elements, but due to the disadvantages of high energy consumption and large volume, they can only be analyzed and detected in the laboratory, which cannot meet the needs of field analysis and detection. Due to the toxicity, carcinogenicity and bioaccumulation of heavy metals, the harm of heavy metal pollution to human health has aroused widespread concern around the world. Heavy metal pollution accidents such as accidental leakage or illegal discharge occur from time to time, and even treated pure water may contain heavy metals due to leaching from pipes. The detection of heavy metal pollution in environmental water usually requires the collection, preservation and transportation of a large number of water samples (250-1000mL) to the laboratory for analysis by benchmark methods, such as Atomic Absorption Spectrometry (AAS), Atomic Fluorescence Spectrometry (Atomic Fluorescence Spectrometry, AFS) and Inductively Coupled Plasma-Optical Emission Spectrometry/Mass Spectrometry (ICP-OES/MS). This detection method not only increases the pressure of logistics transportation, but also the contact of the sample with oxygen, container walls or physical changes in temperature and pressure will inevitably lead to loss of analytes and contamination of samples during sample storage, which will seriously affect Analyze results for accuracy and repeatability. Therefore, there is an urgent need to develop portable analytical instruments to meet the needs of on-site heavy metal pollution analysis.

At present, some heavy metal analysis methods based on portable detectors, such as anodic stripping voltammetry (ASV) and colorimetry (Colorimetry), can be used for the detection of trace heavy metals in the field, but due to the interference of unknown coexisting metal ions, It is not fully applicable to the detection of heavy metals in complex real water samples. X-ray Fluorescence Spectroscopy (XRF) and Laser Induced Breakdown Spectroscopy (LIBS) can analyze elemental characteristics in direct sampling, which are especially suitable for rapid on-site analysis of heavy metals, but are limited by sample heterogeneity. Limitations of insufficient sensitivity and detection sensitivity.

The core component of an atomic emission spectrometer is the atomizer/excitation source, which directly determines the overall analytical performance, size and number of accessories of the entire atomic emission spectrometer. At present, the application of various microplasma excitation sources in atomic emission spectrometry detection systems has accelerated the development of portable instruments, which have shown efficient performance in the field of trace element analysis. Common microplasma includes: Dielectric Barrier Discharge (DBD), Point Discharge (PD), Atmospheric Pressure Glow Discharge (APGD) and the like. Since the power of the microplasma is much lower than that of conventional inductively coupled plasma (ICP) and microwave-induced plasma (MIP) sources, and the evaporation of the solvent and matrix can seriously deteriorate the atomization/excitation capability of the microplasma Therefore, the development of sample injection methods has become an important challenge for microplasma atomic emission spectrometry detection systems. Generally speaking, in order to ensure that the microplasma has sufficient atomization/excitation ability, the ideal method to introduce liquid samples into the microplasma is through chemical/photochemical/electrochemical vapor generation (VaporGeneration, VG) or electrothermal vaporization (Electrothermal Vaporization, ETV) converts analytes into "pure" and "dry" volatile species. Due to the limitations of the reaction conditions, the vapor generation method for sample introduction into the microplasma will result in a limited number of detectable elements, high reagent consumption, and difficulty in measuring multiple elements simultaneously. The electrothermal evaporation based on tungsten wire coil for sample introduction into microplasma is easy to realize the simultaneous determination of multiple elements, but the limited sample loading on the tungsten wire coil hinders the further improvement of its sensitivity, and the service life of the tungsten wire coil limited its long-term use. Inspired by the use of microplasma as an ionization source for mass spectrometry to ionize surface samples in situ, a microplasma excitation source that can excite analytes deposited on a substrate surface for elemental analysis will provide efficient sample introduction and instrument miniaturization. a promising approach. The invention patent authorization announcement number CN104749139A is to use the microwave-induced plasma tail flame with higher energy to trigger the combustion of the sample substrate, and use the combustion heat to promote the atomization and excitation of the element to be tested attached to the substrate to achieve the determination of the element. However, the energy of microplasma such as DBD and PD is so low that it cannot ignite paper. The key to using microplasma excitation source to effectively excite analytes on the substrate surface lies in how to increase the amount of sample introduced into the microplasma excitation source and overcome the The "coffee ring" effect caused by uneven sample deposition. Marcus et al. (Anal. Chem. 2016, 88, 5579-5584.) proposed a proof-of-concept of using liquid sampling APGD to volatilize and excite dry solution residues and detect heavy metals by atomic emission spectroscopy, however this system only provides qualitative analysis of heavy metals .

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a microplasma atomic emission spectrometry detection system capable of introducing samples conveniently and efficiently and a corresponding analysis method using the detection system for on-site heavy metal pollution analysis. Specifically, an electrode sampling DBD microplasma atomic emission spectroscopy detection system and method, the electrode sampling DBD microplasma atomic emission spectroscopy detection system can use the DBD microplasma atomic emission spectroscopy detection system to in-situ analyze the adsorption on the electrode surface the test object.

The electrode sampling DBD microplasma atomic emission spectrum detection system of the present invention includes a DBD microplasma excitation source and a spectrum detection system;

The DBD micro-plasma excitation source includes a sample electrode, a quartz tube with a branch tube, a high-voltage wire wound around the outer wall of the quartz tube, a neon light power supply, a voltage regulator and a gas circuit system;

The material of the sample electrode is a material with conductivity and adsorption of the analyte, and is used to enrich the analyte on the surface of the sample electrode;

The end of the sample electrode enriching the substance to be tested is inserted into the tube of the quartz tube, and is coaxial with the quartz tube;

The input end of the voltage regulator is connected with the alternating current, the output end of the voltage regulator is connected with the input end of the neon light power supply, and the output end of the neon light power supply is respectively connected with the high-voltage wire and the end of the sample electrode that is not enriched with the object to be tested;

The branch pipe on the quartz tube is connected to the gas system;

The spectral detection system includes a lens, an optical fiber and a micro-spectrometer. The lens is connected to the micro-spectrometer through an optical fiber. The lens is arranged in the horizontal direction of the axial or lateral side of the quartz tube to focus the characteristic emission spectrum generated. The micro-spectrometer is used to focus the lens after focusing. The characteristic emission spectrum is detected by optical fiber coupling into a miniature spectrometer.

The electrode sampling DBD micro-plasma atomic emission spectrometry detection system also includes spectrum analysis software corresponding to the computer and the micro-spectrometer, the micro-spectrometer is connected to the computer, and the spectrum analysis software on the computer is used to analyze the spectrum detected by the micro-spectrometer. The miniature spectrometer can be an Ocean Optics QE65000 spectrometer, and the spectral analysis software corresponding to the spectrometer is SpectraSuite.

The micro-plasma generated by the micro-plasma excitation source is generated in the tube of the quartz tube, and the sample electrode is immersed in the micro-plasma;

The sample electrode preferably includes an electrode head and a connection support; one end of the electrode head is connected to the connection support; the electrode head is used to enrich heavy metals, and the material of the electrode head is preferably activated carbon, graphene, stainless steel, etc. The connection support is preferably a hollow metal tube, such as a hollow stainless steel tube and a hollow tungsten tube, for supporting and connecting high-voltage wires. Preferably, the diameter of the electrode tip is 0.4-1.2mm and the length is 2-8mm; the inner diameter of the hollow metal tube is 0.4-1.2mm, the thickness of the tube wall is 0.05-0.1mm, and the length is 40-100mm; the outer diameter of the electrode tip is the same as the inner diameter of the hollow metal tube , After the electrode head is inserted into the hollow metal tube, the exposed length of the electrode head is 1-7mm.

The sample electrode is also equipped with a peristaltic pump and a heating table. The peristaltic pump is used to flow the solution containing the object to be tested into the sample electrode at a uniform speed, and the heating table is used to dry the sample electrode.

The outer diameter of the quartz tube with branch tubes is 1-4 mm, the thickness of the tube wall is 0.05-0.1 mm, and the length is 60-100 mm.

The voltage regulator is used to control the voltage applied to the sample electrode and the high-voltage wire by the neon power supply by adjusting the output voltage of the voltage regulator.

The high-voltage wires are preferably copper wires.

An electrode sampling DBD micro-plasma atomic emission spectroscopy analysis method of the present invention adopts the above-mentioned electrode sampling DBD micro-plasma atomic emission spectroscopy detection system, comprising the following steps:

step 1:

The sample solution containing the analyte is flowed over the surface of the sample electrode at a constant flow rate by a peristaltic pump, and pre-concentrated to obtain a sample electrode with pre-concentrated analyte;

The sample electrode with pre-concentrated analyte is heated to remove moisture to obtain a sample electrode enriched with analyte;

Step 2:

Insert the sample electrode enriched with the analyte into the tube of the quartz tube with the branch tube, and pass the micro-plasma discharge gas into the quartz tube through the gas circuit system;

Connect the output end of the neon light power supply to the end of the sample electrode away from the enriched object to be tested, and connect the other output end of the neon light power supply to the high-voltage wire wound on the outer wall of the quartz tube;

The output end of the voltage regulator is connected with the input end of the neon light power supply, and the input end of the voltage regulator is connected with the alternating current. The voltage of the sample electrode and the high-voltage wire enriched with the analyte is adjusted by a voltage regulator to ignite the plasma voltage, and then the voltage is raised to a voltage that can excite the analyte. In situ excitation in vivo, the object to be tested on the surface of the sample electrode can complete the excitation process within 3-5 seconds to generate a characteristic emission spectrum;

Step 3:

The characteristic emission spectrum is focused by a lens and coupled to a miniature spectrometer for detection through an optical fiber.

The electrode sampling DBD micro-plasma atomic emission spectrometry analysis method further comprises: displaying the spectral intensity of each object to be tested by using the characteristic emission spectrum detected by the micro-spectrometer through computer spectrum analysis software, and using the spectral peak height of each object to be tested for quantification Analysis to obtain the type and corresponding content of the analyte in the solution.

In the step 1, the constant flow rate is preferably 3-10 mL/min.

In the step 1, the heating temperature is preferably 50-70° C., and the heating time is 3-10 min.

In the step 1, the multiple sample electrodes can be injected simultaneously according to the multi-channel property of the peristaltic pump.

In the step 2, the input power of the neon light power supply is 220V, and the output voltage is a high-voltage power supply of 6kV and 30mA.

In the step 2, the micro-plasma discharge gas is preferably an inert gas, more preferably argon or helium.

In the step 2, the ignition plasma voltage is determined according to the thickness of the quartz tube and the relative position of the sample electrode and the high-voltage wire, and is preferably 3.4-3.6kV.

In the step 2, the voltage for exciting the object to be tested is determined according to the fact that the quartz tube is not broken down and the object to be tested can generate a characteristic emission signal, preferably 3.6-6.0 kV.

In the step 3, the distance between the micro-plasma and the lens is preferably 6-12 cm.

Compared with the prior art, an electrode sampling DBD microplasma atomic emission spectrometry detection system and method of the present invention has the following advantages:

(1) The most important thing of the present invention is to integrate sampling, pre-concentration and micro-plasma excitation on one sample electrode, which not only simplifies the pre-processing steps of the sample, improves portability, but also significantly improves the micro-plasma atomic emission spectrum The sensitivity of the analyte analysis of the detection system, specifically the detection limit of cadmium and lead elements, can reach the sub-ppb level under optimized conditions, and the detection limit can meet the pollution detection standard.

(2) The dielectric barrier discharge micro-plasma is used as the excitation source, which can be operated under atmospheric pressure and has low energy consumption; the micro-spectrometer is used for detection, which is small in size and low in cost. The proposed inventive system lays the foundation for the miniaturization and field analysis of atomic spectroscopy instruments.

(3) The device and method provided by the present invention are used to detect and analyze the sample, which has a high analysis speed, and the time required for a single detection of the sample electrode enriched with the analyte is only 3-5 seconds, which is very suitable for batch samples rapid high-throughput analysis.

(4) And the device and method provided by the present invention can provide a convenient and efficient sample introduction method for on-site contamination analysis of the analyte. In the present invention, the sample electrode is used as the analyte capture carrier through simple liquid-solid phase transition. Without any sample transmission channel, by simply adjusting the electric field intensity, the analyte adsorbed on the surface of the sample electrode can be quantitatively analyzed by the microplasma atomic emission spectrometry detection system.

Description of drawings

Figure 1 is the device diagram of the electrode sampling DBD microplasma atomic emission spectrometry detection system, in which 1-sample electrode, 2-quartz tube with branch tube, 3-high voltage wire, 4-neon lamp power supply, 5-voltage regulator, 6- -Pneumatic system, 7-lens, 8-fiber, 9-miniature spectrometer.

Figure 2 is the sample introduction unit of the electrode sampling DBD microplasma atomic emission spectrometry detection system, wherein: 10- activated carbon rod, 11- hollow stainless steel tube, 12- peristaltic pump, 13- heating stage.

FIG. 3 is the emission spectrum of the standard solution without cadmium and 6 μg/L of cadmium element measured by the device and method of the present invention.

Fig. 4 is the emission spectrogram of the standard solution containing no lead and 70 μg/L lead element measured by the device and method of the present invention.

Detailed ways

The present invention will be described in further detail below with reference to the accompanying drawings and embodiments, and the following embodiments are only used to illustrate the present invention, but not to limit the present invention.

The equipment and instruments used in the following examples are commercially available unless otherwise specified.

Example 1

Figure 1 is a schematic diagram of the overall structure of the device of the electrode sampling DBD microplasma atomic emission spectrometry detection system. As shown in Figure 1, the proposed electrode sampling DBD microplasma atomic emission spectroscopy detection system device includes a DBD microplasma excitation source and a spectral detection system;

The DBD microplasma excitation source includes a sample electrode 1, a quartz tube with a branch tube 2, and a high-voltage wire 3 wound around the outer wall of the quartz tube. The high-voltage wire in this embodiment is a copper wire, a neon light power supply 4, a voltage regulator 5 and a gas circuit system. 6;

The sample electrode 1 includes an activated carbon rod 10 and a hollow stainless steel tube 11, and one end of the activated carbon rod 10 is connected to one end of the hollow stainless steel tube 11;

One end of the hollow stainless steel tube 11 of the sample electrode 1 and one end of the high-voltage wire 3 are respectively connected to the output end of the neon lamp power supply 4 . The input end of the neon light power supply 4 is connected to the output end of the voltage regulator 5, and the input end of the voltage regulator 5 is connected to the 220V power supply. The branch port of the quartz tube 2 with branch pipe is connected to the gas circuit system 6 for introducing the micro-plasma discharge gas. The DBD microplasma is generated inside the quartz tube 2 of the branch pipe, and the sample electrode 1 is immersed in the DBD microplasma. The high voltage applied between the sample electrode 1 and the high voltage wire 3 is controlled by the neon lamp power supply 4 by adjusting the output voltage of the voltage regulator 5 .

The spectral detection system includes a lens 7, an optical fiber 8 and a micro-spectrometer 9. The lens 7 is connected to the micro-spectrometer 9 through an optical fiber 8. The lens is arranged in the horizontal direction of the axial or lateral side of the quartz tube with branch 2 away from its branch port. The object to be tested on the surface of the sample electrode 1 is excited by the DBD microplasma, and the characteristic light of the object to be tested is emitted along the quartz tube 2 with a branch tube, and after being focused by the lens 7, it is coupled to the micro-spectrometer 9 through the optical fiber 8 to detect and amplify the signal. Finally, after the spectral intensity of each test object is displayed by the spectral analysis software on the computer, the peak height is used for quantitative analysis, so as to realize the detection of the test object.

In this embodiment, the activated carbon rod 10 has a diameter of 0.9 mm and a length of 5 mm; the hollow stainless steel tube 11 has an inner diameter of 0.9 mm, a tube wall thickness of 0.05 mm and a length of 50 mm; after the activated carbon rod 10 is inserted into the hollow stainless steel tube 11, the activated carbon rod 10 is removed from the hollow The stainless steel tube 11 protrudes by 4 mm. According to the multi-channel property of the peristaltic pump 12, a plurality of sample electrodes 1 can be injected simultaneously.

The quartz tube 2 with the branch tube has an outer diameter of 3.3 mm, a tube wall thickness of 0.8 mm, and a length of 85 mm. The high-voltage wire 3 has a diameter of 0.5mm. The carrier gas was argon, and the gas flow rate was 600 mLmin ^-1 . The neon light power supply 4 can use a high voltage source with an input voltage of 220V and an output of 6kV and 30mA. The voltage regulator 5 has an input voltage of 220V and an output voltage of 0-250V. The distance between the micro-plasma discharge area and the center of the lens is 10 cm.

The method for detecting heavy metal elements using the device of the present invention will be described below.

The sample introduction unit of the electrode sampling DBD microplasma atomic emission spectrometry detection system is shown in Figure 2, and the sample solution containing the analyte is passed through the surface of the activated carbon rod 10 through the peristaltic pump 12 at a constant flow rate of 10 mL/min for pre-concentration. The sample electrode 1 with pre-concentrated analyte is obtained. Then, the sample electrode 1 is dried to remove water by the heating stage 13 to obtain a sample electrode enriched with the analyte. The temperature of the heating table was 60 °C, and the heating time was 5 min.

Insert the sample electrode for enriching the analyte into the tube of the quartz tube, and pass DBD micro-plasma discharge gas into the quartz tube through the gas circuit system. In this example, argon gas is used, and the output end of the neon power supply and the sample electrode are kept away from the rich Connect one end of the object to be tested, and connect the other output end of the neon power supply to the high-voltage wire wound on the outer wall of the quartz tube;

Connect the power supply, and adjust the voltage of the sample electrode and high-voltage wire for enriching the test object through the voltage regulator to ignite the plasma voltage, which is 3.4kV in this example, and then increase the voltage to the voltage that can excite the test object. At this time The analyte adsorbed on the surface of the sample electrode enriched with the analyte is excited in situ by the microplasma. In this embodiment, the voltage to excite the analyte is 5.8kV, and the analyte on the surface of the sample electrode is excited within 3-5 seconds. The excitation process can be completed to generate the characteristic emission spectrum. The characteristic emission spectrum detected by the micro-spectrometer is used to display the spectral intensity of each analyte through computer spectrum analysis software, and the spectral peak height of each analyte is used for quantitative analysis to obtain the type and corresponding content of the analyte in the solution.

Taking cadmium and lead as an example, the feasibility of using the invented electrode sampling DBD microplasma atomic emission spectrometry detection system and the analysis method using the system is described.

3 is the emission spectrum of the standard solution containing no cadmium Cd and 6 μg/L cadmium measured by the detection system and method of the present invention, the abscissa represents the wavelength range, and the ordinate represents the emission signal intensity. It can be seen from FIG. 3 that the specific cadmium atomic emission line at 228.8 nm is clearly separated from the blank emission spectrum, which verifies the feasibility of the detection device and method of the present invention. Continue to perform multiple tests with different concentrations of cadmium to illustrate the sensitivity of the established method. When the sample volume is 50mL and the peristaltic pump injection time is 5min, the experimental results show that the detection limit of cadmium (calculated by multiplying the standard deviation of 11 blank samples by 3 and dividing by the slope of the regression equation of the standard curve) is as low as 0.03 μg/L, linear range 0.1-12 μg/L, signal RSD (relative standard deviation of 11 measurements of 5 μg/L Cd) below 3%. The detection limit can reach the pollution detection standard.

4 is the emission spectrum of the standard solution containing lead-free Pb and 70 μg/L lead measured by the device and method of the present invention, the abscissa represents the wavelength range, and the ordinate represents the emission signal intensity. It can be seen from FIG. 4 that the specific lead atom emission lines at 368.3 nm and 363.9 nm are clearly separated from the blank emission spectrum, which verifies the feasibility of the detection device and method of the present invention. Continue to perform multiple tests with different concentrations of lead to illustrate the sensitivity of the established method. When the sample volume is 50mL and the peristaltic pump injection time is 5min, the experimental results show that the detection limit of lead (calculated by multiplying the standard deviation of 11 blank samples by 3 and dividing by the slope of the regression equation of the standard curve) is as low as 0.6 μg/L, linear range 2-100 μg/L, signal RSD (relative standard deviation of 11 measurements for 50 μg/L Pb) below 4%. The detection limit can reach the pollution detection standard.

Example 2

The structure of the electrode sampling DBD microplasma atomic emission spectrometry detection system is the same as that of Example 1, except that the activated carbon rod 10 included in the sample electrode 1 is a hollow stainless steel tube, that is, the sample electrode 1 is an integrated hollow stainless steel tube. At this time, the enrichment ability of the sample electrode 1 to be tested is weaker than that of the sample electrode 1 used in Example 1.

A method for detecting heavy metal elements by electrode sampling DBD micro-plasma atomic emission spectrometry is the same as that in Embodiment 1. Taking cadmium as an example, the emission spectrogram of the standard solution containing cadmium elements measured by the detection system and method of the present invention, The characteristic emission spectrum of cadmium appears at 228.8 nm. When the Cd concentration (6 μg/L) measured in Example 1 is 1% of that in Example 2, at 228.8 nm, the spectral intensity of cadmium in Example 1 is 8 times higher than that in Example 2 by computer spectrum analysis software.

Example 3

The electrode sampling DBD microplasma atomic emission spectrometry detection system has the same structure as that of Example 1, except that the voltage to excite the object to be tested is 4.0 kV.

A method for detecting heavy metal elements by electrode sampling DBD micro-plasma atomic emission spectrometry is the same as that in Embodiment 1. Taking cadmium as an example, the emission spectrogram of the standard solution containing cadmium elements measured by the detection system and method of the present invention, The characteristic emission spectrum of cadmium appears at 228.8 nm, when the Cd concentration (6 μg/L) measured in Example 1 is the same as that of Example 3, at 228.8 nm, Example 1 displays the spectrum of cadmium by computer spectrum analysis software The strength is 2.5 times that of Example 3.

Example 4

The electrode sampling DBD microplasma atomic emission spectrometry detection system of the present invention is used to measure cadmium and lead in lake water, and a method for detecting heavy metal elements by electrode sampling DBD microplasma atomic emission spectrometry is the same as that in Example 1, except that the lake water is different. The water samples were filtered through a 0.22 μm filter for analysis.

In this example, the obtained spectral peak heights of cadmium and lead are converted into concentrations according to the regression equation of the standard curve, and the concentration of cadmium in the lake water is 0.34±0.01 μg/L, and lead is not detected. The spiked recoveries were 96.5% and 100.5% at L and 50 μg/L.

Example 5

The electrode sampling DBD microplasma atomic emission spectrometry detection system of the present invention is used to measure cadmium and lead in drinking water, and a method for detecting heavy metal elements by electrode sampling DBD microplasma atomic emission spectrometry is the same as that in Example 1.

In this example, the obtained spectral peak heights of cadmium and lead were converted into concentrations according to the regression equation of the standard curve. Neither cadmium nor lead was detected. When cadmium and lead were spiked at 5 μg/L and 20 μg/L, respectively, the standard recovery rate was 95.5% and 101.4%.

Compared with the existing in-situ surface analysis methods, the volume-type in-situ micro-plasma excitation method proposed by the present invention overcomes the coffee ring effect caused by the uneven dry residue. In addition, the efficient microplasma excitation capability and the use of activated carbon supports with preconcentration capabilities for liquid samples further enhance the sensitivity of the system.

The above embodiments are merely to describe the embodiments of the present invention, and not to limit the scope. On the premise of not departing from the design spirit of the present invention, various modifications and improvements made to the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims (9)

1. an electrode sampling DBD micro-plasma atomic emission spectroscopy detection system, is characterized in that, this electrode sampling DBD micro-plasma atomic emission spectroscopy detection system comprises a DBD micro-plasma excitation source, a spectrum detection system; The DBD micro-plasma excitation source includes a sample electrode, a quartz tube with a branch tube, a high-voltage wire wound around the outer wall of the quartz tube, a neon light power supply, a voltage regulator and a gas circuit system; The material of the sample electrode is a material with conductivity and adsorption of the analyte, and is used to enrich the analyte on the surface of the sample electrode; The end of the sample electrode enriching the substance to be tested is inserted into the tube of the quartz tube, and is coaxial with the quartz tube; The sample electrode includes an electrode head and a connection support; one end of the electrode head is connected with the connection support; the electrode head is used for enriching heavy metals; the connection support is a hollow metal tube, which is used for supporting and connecting high-voltage wires; the diameter of the electrode head is 0.4 -1.2mm, length 2-8mm; hollow metal tube inner diameter 0.4-1.2mm, tube wall thickness 0.05-0.1mm, length 40-100mm; the outer diameter of the electrode tip is the same as the inner diameter of the hollow metal tube, and the electrode tip is inserted into the hollow metal tube After, the exposed length of the electrode head is 1-7mm; The input end of the voltage regulator is connected with the alternating current, the output end of the voltage regulator is connected with the input end of the neon light power supply, and the output end of the neon light power supply is respectively connected with the high-voltage wire and the end of the sample electrode that is not enriched with the object to be tested; The branch pipe on the quartz tube is connected to the gas system; The spectral detection system includes a lens, an optical fiber and a micro-spectrometer. The lens is connected to the micro-spectrometer through an optical fiber. The lens is arranged in the horizontal direction of the axial or lateral side of the quartz tube to focus the characteristic emission spectrum generated. The micro-spectrometer is used to focus the lens after focusing. The characteristic emission spectrum is detected by optical fiber coupling into a miniature spectrometer. 2. The electrode sampling DBD microplasma atomic emission spectroscopy detection system according to claim 1, wherein the electrode sampling DBD microplasma atomic emission spectroscopy detection system also comprises a spectrum corresponding to a computer and a miniature spectrometer Analysis software, the micro-spectrometer is connected with the computer, and the spectrum analysis software on the computer is used to analyze the spectrum detected by the micro-spectrometer. 3. electrode sampling DBD micro-plasma atomic emission spectrometry detection system according to claim 1, is characterized in that, described sample electrode is also provided with peristaltic pump and heating table, and peristaltic pump is used for containing test object The solution flows into the sample electrode at a uniform rate, and the heating stage is used to dry the sample electrode. 4. The electrode sampling DBD microplasma atomic emission spectrometry detection system according to claim 1, wherein the outer diameter of the quartz tube with branch tube is 1-4mm, the tube wall thickness is 0.05-0.1mm, the length 60-100mm. 5. an electrode sampling DBD micro-plasma atomic emission spectrometry analysis method, is characterized in that, adopts the electrode sampling DBD micro-plasma atomic emission spectrometry detection system described in any one of claim 1-4, comprises the following steps: step 1: The sample solution containing the analyte is flowed over the surface of the sample electrode at a constant flow rate by a peristaltic pump, and pre-concentrated to obtain a sample electrode with pre-concentrated analyte; The sample electrode with pre-concentrated analyte is heated to remove moisture to obtain a sample electrode enriched with analyte; Step 2: Insert the sample electrode enriched with the analyte into the tube of the quartz tube with the branch tube, and pass the micro-plasma discharge gas into the quartz tube through the gas circuit system; Connect the output end of the neon light power supply to the end of the sample electrode away from the enriched object to be tested, and connect the other output end of the neon light power supply to the high-voltage wire wound on the outer wall of the quartz tube; The output end of the voltage regulator is connected to the input end of the neon light power supply, and the input end of the voltage regulator is connected to the alternating current; the voltage of the sample electrode and the high-voltage wire for enriching the test object is adjusted by the voltage regulator to ignite the plasma voltage, and then the voltage Raised to the voltage that can excite the analyte, the analyte adsorbed on the surface of the sample electrode is excited in situ by the microplasma, and the analyte on the surface of the sample electrode can complete the excitation process within 3-5 seconds, resulting in characteristic emission spectrum; Step 3: The characteristic emission spectrum is focused by a lens and coupled to a miniature spectrometer for detection through an optical fiber. 6. The electrode sampling DBD micro-plasma atomic emission spectrometry analysis method according to claim 5, wherein the electrode sampling DBD micro-plasma atomic emission spectrometry analysis method also comprises the feature of detecting the micro-spectrometer The emission spectrum is used to display the spectral intensity of each analyte by computer spectrum analysis software, and the spectral peak height of each analyte is used for quantitative analysis to obtain the type and corresponding content of the analyte in the solution. 7. The electrode sampling DBD microplasma atomic emission spectrometry analysis method according to claim 5, wherein in the step 1, the constant flow rate is 3-10mL/min; the heating temperature is 50～70°C, The heating time is 3~10min. 8. electrode sampling DBD micro-plasma atomic emission spectrometry analysis method according to claim 5, is characterized in that, in described step 2, the input power supply of neon lamp power supply is 220V, and the output voltage is the high-voltage power supply of 6kV, 30mA . 9 . The electrode sampling DBD microplasma atomic emission spectrometry analysis method according to claim 5 , wherein in the step 2, the ignition plasma voltage is 3.4-3.6kV; the voltage to excite the object to be tested is 3.6-6.0kV.

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