Liquid cathode glow discharge spectrometer with optical filter automatic switching function

Abstract

The utility model belongs to the technical field of atomic spectrum metal element analysis, and particularly relates to a liquid cathode glow discharge spectrometer with an optical filter automatic switching function, which comprises a solid anode, a liquid cathode, an optical filter assembly, a circular convex lens and an optical fiber spectrometer, a glow discharge area is arranged between the solid anode and the liquid cathode, the optical fiber spectrometer is arranged outside the glow discharge area, and the circular convex lens is arranged between the glow discharge area and the optical fiber spectrometer; the optical filter assembly is arranged between the glow discharge area and the circular convex lens and comprises a rotating disc and a plurality of through holes distributed in the circumference of the rotating disc, and at least one through hole is provided with an optical filter. According to the liquid cathode glow discharge spectrometer, different optical filters can be switched and selected according to different measured wavelengths of to-be-measured elements and interference conditions of adjacent spectral lines (bands), so that the working efficiency is improved, the consumption of a test solution of a test sample is reduced, the measurement precision is improved, and the labor time is saved.

Description

Technical Field

[0001] This invention belongs to the field of atomic spectroscopy metal element analysis technology, specifically relating to a liquid cathode glow discharge spectrometer with automatic filter switching function. Background Technology

[0002] Liquid cathode glow discharge emission spectrometers can be used to determine various metal elements in liquid samples, including lead, mercury, silver, thallium, cadmium, chromium, manganese, iron, copper, zinc, potassium, lithium, sodium, calcium, magnesium, gallium, and indium. The instrument applies a voltage of several hundred to several thousand volts between the metal anode and the cathode of the sample solution, causing ionization discharge of the gas between the electrodes to form a microplasma. During the discharge, the metal ions of the analyte volatilize or sputter into the microplasma, where they are thermally excited and generate emission spectra. Quantitative detection of the analyte is achieved through the characteristic radiation of different metal elements.

[0003] During the volatilization or sputtering of metal ions of the analyte into the microplasma, complex coexisting matrix components also enter the plasma, forming matrix radiation bands. In the quantitative analysis of some target elements, the analytical spectral lines are easily affected by severe spectral interference caused by the continuous adjacent band radiation of molecular groups, affecting the accuracy of the measurement results. Installing filters can significantly improve this problem. However, when the target analyte changes, the filter usually needs to be replaced, which limits the realization of multi-element analysis with a single sample injection in liquid cathode glow discharge emission spectrometers. This not only significantly affects the analytical efficiency but also results in excessive consumption of test sample solution. Utility Model Content

[0004] To address the shortcomings of existing technologies, this invention provides a liquid cathode glow discharge spectrometer with automatic filter switching. Depending on the wavelength of the analyte and the interference from adjacent spectral lines (bands), different filters can be selected, significantly improving the efficiency of multi-element analysis with interference from adjacent spectral lines (bands), reducing the consumption of test sample solution, and improving measurement accuracy by effectively eliminating interference from molecular group emission spectra. It also eliminates the need for manual filter replacement, enabling multi-element determination with different adjacent spectral line (band) interference without manual filter disassembly, saving considerable time spent manually changing filters.

[0005] Specifically, this utility model provides the following technical solution:

[0006] A liquid cathode glow discharge spectrometer with automatic filter switching function includes a solid anode, a liquid cathode, a filter assembly, a circular convex lens, and a fiber optic spectrometer;

[0007] A glow discharge region is located between the solid anode and the liquid cathode. The fiber optic spectrometer is located outside the glow discharge region, and the circular convex lens is located between the glow discharge region and the fiber optic spectrometer.

[0008] The filter assembly is disposed between the glow discharge region and the circular convex lens, and includes a rotating disk and a plurality of through holes arranged circumferentially on the rotating disk, wherein at least one of the through holes is provided with a filter.

[0009] Preferably, the filter assembly is arranged parallel to the circular convex lens. As the rotating disk of the filter assembly rotates, the central axis of the circular convex lens passes through each of the through holes on the rotating disk in sequence. After successful ignition, light passes through the through holes through which the central axis of the circular convex lens passes, enters the circular convex lens, is focused by the circular convex lens, and then enters the fiber optic spectrometer to collect the required data. If a filter is provided in the through hole, the filter can filter the light passing through the through hole.

[0010] Preferably, a fan-shaped light-blocking plate is also included; the fan-shaped light-blocking plate is disposed between the glow discharge region and the filter assembly. The fan-shaped light-blocking plate is used to block light from passing through other through holes, ensuring that light only passes through the through hole through which the central axis of the circular convex lens passes, thereby eliminating stray light interference from different channels.

[0011] Preferably, among the through holes arranged circumferentially on the rotating disk, one through hole is not equipped with a filter, while the other through holes are equipped with different types of filters.

[0012] Preferably, the size of the through hole on the rotating disk is 2mm to 50mm (if the through hole is a circular hole, the diameter is 2mm to 50mm; if the through hole is a square hole, the side length is 2mm to 50mm).

[0013] The diameter of the circular convex lens is 10mm to 25mm, preferably 16mm to 20mm.

[0014] Preferably, the filter assembly is located 2-5 cm outside the glow discharge region; studies have found that if the distance is less than the above range, it will be corroded by acid mist; if the distance is greater than the above range, there will be light energy loss.

[0015] The distance between the filter assembly and the circular convex lens is 0-5cm, preferably 0.2-2cm; research has found that if the distance between the filter assembly and the circular convex lens is too large, it will cause energy loss.

[0016] Preferably, the fiber optic probe of the fiber optic spectrometer is located at the focal point of the outgoing light rays from the circular convex lens.

[0017] Preferably, a rotating shaft is fixedly connected to the center of the rotating disk, and the rotating shaft is driven to rotate by a motor.

[0018] Preferably, the liquid cathode includes a glass tube with one end open towards the solid anode, and a graphite auxiliary electrode is fitted over the glass tube. The solid anode and the graphite auxiliary electrode are connected to a high-voltage power supply.

[0019] The beneficial effects achieved by this utility model are as follows:

[0020] (1) The present invention provides a liquid cathode glow discharge spectrometer with automatic filter switching function. By driving the motor to rotate the rotating disk, the specific bandpass (cutoff) filter or no filter is switched, so that different filter positions can be automatically selected according to the different wavelengths of the analyte and the interference of adjacent spectral lines (bands).

[0021] (2) The liquid cathode glow discharge spectrometer with automatic filter switching function provided by this utility model saves a lot of time for manual filter replacement, greatly improves the working efficiency of multi-element analysis with interference from adjacent spectral lines (bands), reduces the consumption of test sample solution, and improves the measurement accuracy by effectively eliminating the interference of molecular group emission spectrum.

[0022] (3) The present invention provides a liquid cathode glow discharge spectrometer with automatic filter switching function, which eliminates stray light interference from different channels by setting a fan-shaped light-blocking plate between the glow discharge region and the filter assembly.

[0023] (4) The liquid cathode glow discharge spectrometer with automatic filter switching function provided by this utility model ensures that the wavelength range of the transmitted light from the filter does not deviate from the allowable value by limiting the diameter of the through hole on the rotating disk, the diameter of the circular convex lens, and the setting position. In addition, while ensuring the feasibility of component processing, it effectively avoids the corrosion of optical devices by acid mist generated during the liquid cathode glow discharge process; it minimizes light energy loss to the greatest extent, ensures the optimal light intensity of the spectral line to be measured, and further improves the detection sensitivity.

[0024] (5) The present invention provides a liquid cathode glow discharge spectrometer with automatic filter switching function, which is applied to the single-injection simultaneous determination of thallium and lithium content, effectively eliminating matrix interference, with detection limits of less than 1.0 μg / L for thallium and lithium, and repeatability RSD of less than 10%. Attached Figure Description

[0025] Figure 1This is a simplified structural diagram of the liquid cathode glow discharge spectrometer in Example 1; wherein, 1 is the solid anode, 2 is the graphite auxiliary electrode, 3 is the high-voltage power supply, 4 is the glow discharge region, 5 is the filter assembly, 6 is the motor, 7 is the circular convex lens, 8 is the fiber optic probe, 9 is the fiber optic spectrometer, 10 is the waste liquid, 11 is the liquid cathode, 12 is the sample injection solution, and 13 is the fan-shaped light-blocking plate.

[0026] Figure 2 This is a simplified structural diagram of the filter assembly in Example 1; where 14 is the reference position (without filter), 15 is the first filter 1#, 16 is the second filter, 17 is the rotating shaft, 18 is the third filter, 19 is the fourth filter, and 20 is the fifth filter. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate this utility model, but are not intended to limit the scope of this utility model. Where specific technologies or conditions are not specified in the embodiments, they shall be performed in accordance with the technologies or conditions described in the literature in the field, or in accordance with the product manual.

[0028] Example 1

[0029] A liquid cathode glow discharge spectrometer with automatic filter switching function, see [link to relevant documentation]. Figure 1-2 It includes a solid anode 1, a liquid cathode 11, a fan-shaped light-blocking plate 13, a filter assembly 5, a circular convex lens 7, and a fiber optic spectrometer 9;

[0030] Between the solid anode 1 and the liquid cathode 11 is a glow discharge region 4, and the fiber optic spectrometer 9 is disposed outside the glow discharge region 4; the circular convex lens 7 has a diameter of 18 mm and is disposed between the glow discharge region 4 and the fiber optic spectrometer 9, and the fiber optic probe 8 of the fiber optic spectrometer 9 is located at the focal point of the emitted light from the circular convex lens 7.

[0031] The filter assembly 5 is disposed between the glow discharge region 4 and the circular convex lens 7, and is located 3 cm outside the glow discharge region 4, and 1 cm away from the circular convex lens 7.

[0032] The filter assembly 5 includes a rotating disk and six circular through holes with a diameter of 10 mm evenly distributed around the circumference of the rotating disk. One of the through holes is a reference position 14, which is not equipped with a filter. The other through holes are respectively equipped with a first filter 15, a second filter 16, a third filter 18, a fourth filter 19, and a fifth filter 20. A rotating shaft 17 is fixedly connected to the middle of the rotating disk, and the rotating shaft 17 is driven to rotate by a motor 6.

[0033] The filter assembly 5 is arranged parallel to the circular convex lens 7. As the rotating disk of the filter assembly 5 rotates, the central axis of the circular convex lens 7 can pass through each through hole on the rotating disk in sequence.

[0034] The fan-shaped light-blocking plate 13 is disposed between the glow discharge region 4 and the filter assembly 5 to ensure that light only passes through the through hole through which the central axis of the circular convex lens 7 passes, thereby eliminating stray light interference from different channels.

[0035] The liquid cathode 11 includes a glass tube with one end open towards the solid anode 1. A graphite auxiliary electrode 2 is placed over the glass tube. The solid anode 1 and the graphite auxiliary electrode 2 are connected to a high-voltage power supply 3.

[0036] Before ignition, the filter assembly rotating disk 5 is in reference position 14 (i.e., the central axis of the circular convex lens 7 passes through reference position 13). When a voltage of several hundred to several thousand volts is applied between the solid electrode 1 and the graphite auxiliary cathode 2 through the high-voltage power supply 3, the sample solution 12 enters the glass tube and acts as a liquid cathode. The air between the liquid cathode and the solid electrode 1 is ionized to generate micro-plasma, and ignition is successful. Then, according to the different elements to be measured, the rotating disk of the filter assembly 5 is driven by the motor 6 to the first selected filter position to collect the required data. After the data collection is completed, the rotating disk of the filter assembly 5 is driven by the motor 6 to the second selected filter position to collect the required data; and so on. After the spectral data of all elements are collected, the rotating disk of the filter assembly 5 is driven by the motor 6 back to reference position 14, and then the glow discharge ends, and the waste liquid 10 is discharged through the quartz capillary.

[0037] Specifically, the liquid cathode glow discharge spectrometer with automatic filter switching function was applied to the simultaneous determination of thallium and lithium content in a single injection. The wavelength for thallium determination was 535 nm, requiring the selection of a filter to eliminate matrix spectral interference. The wavelength for lithium determination was 671 nm, with no significant matrix spectral interference. A reference position (without a filter, as adding a filter would significantly reduce sensitivity) was used. A tungsten discharge anode was employed, with a discharge voltage of 700 V, a discharge current of 60 mA, an injection flow rate of 4.0 mL / min, and an injection volume of 2.5 mL. Industrial wastewater in which thallium and lithium were not detected by inductively coupled plasma mass spectrometry was used as a blank matrix. Thallium and lithium single-element standard solutions were added to prepare a standard series containing thallium and lithium concentrations of 5 μg / L, 10 μg / L, 20 μg / L, 50 μg / L, and 100 μg / L, respectively. Standard glow intensity was measured at different concentration gradients from low to high concentrations. The fitted working curves for thallium were obtained as y = 86x + 33 (y is emission intensity, x is thallium concentration); and for lithium, as y = 124x + 33 (y is emission intensity, x is lithium concentration). Eleven repeated measurements were performed on the blank matrix solution. The detection limits for thallium and lithium were calculated by dividing the slope by three times the standard deviation of their glow intensity. The detection limits for thallium and lithium were 0.87 μg / L and 0.55 μg / L, respectively. Seven repeatability tests were performed on industrial wastewater blank matrix samples with added 10 μg / L thallium and lithium. The relative standard deviations were 4.8% and 6.2%, respectively.

[0038] Liquid cathode glow discharge spectrometers without automatic filter switching require the filter to be removed and the light adjusted by professionals after lithium determination. In contrast, liquid cathode glow discharge spectrometers with automatic filter switching offer significant improvements in analytical efficiency, sample consumption, and reduced requirements for analysts while maintaining analytical performance.

[0039] Although the present invention has been described in detail above with general descriptions, specific embodiments, and experiments, some modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A liquid cathode glow discharge spectrometer with automatic filter switching function, characterized in that, Includes solid anode, liquid cathode, filter assembly, circular convex lens and fiber optic spectrometer; A glow discharge region is located between the solid anode and the liquid cathode. The fiber optic spectrometer is located outside the glow discharge region, and the circular convex lens is located between the glow discharge region and the fiber optic spectrometer. The filter assembly is disposed between the glow discharge region and the circular convex lens, and includes a rotating disk and a plurality of through holes arranged circumferentially on the rotating disk, wherein at least one of the through holes is provided with a filter.

2. A liquid cathode glow discharge spectrometer with automatic filter switching function according to claim 1, characterized in that, The filter assembly is arranged parallel to the circular convex lens. As the rotating disk of the filter assembly rotates, the central axis of the circular convex lens can pass through each of the through holes on the rotating disk in sequence.

3. A liquid cathode glow discharge spectrometer with automatic filter switching function according to claim 1 or 2, characterized in that, It also includes a fan-shaped light-blocking plate; the fan-shaped light-blocking plate is disposed between the glow discharge region and the filter assembly.

4. A liquid cathode glow discharge spectrometer with automatic filter switching function according to claim 1 or 2, characterized in that, Of the through holes arranged circumferentially on the rotating disk, one through hole is not fitted with a filter, while the other through holes are fitted with different types of filters.

5. A liquid cathode glow discharge spectrometer with automatic filter switching function according to claim 1 or 2, characterized in that, The size of the through hole on the rotating disk is 2mm~50mm; The diameter of the circular convex lens is 10mm to 25mm.

6. A liquid cathode glow discharge spectrometer with automatic filter switching function according to claim 5, characterized in that, The diameter of the circular convex lens is 16mm~20mm.

7. A liquid cathode glow discharge spectrometer with automatic filter switching function according to claim 1 or 2, characterized in that, The filter assembly is located 2-5 cm outside the glow discharge region; The distance between the filter assembly and the circular convex lens is 0 to 5 cm.

8. A liquid cathode glow discharge spectrometer with automatic filter switching function according to claim 7, characterized in that, The distance between the filter assembly and the circular convex lens is 0.2-2 cm.

9. A liquid cathode glow discharge spectrometer with automatic filter switching function according to claim 1 or 2, characterized in that, The fiber optic probe of the fiber optic spectrometer is located at the focal point of the outgoing light rays from the circular convex lens.

10. A liquid cathode glow discharge spectrometer with automatic filter switching function according to claim 1 or 2, characterized in that, A rotating shaft is fixedly connected to the center of the rotating disk, and the rotating shaft is driven to rotate by a motor.

11. A liquid cathode glow discharge spectrometer with automatic filter switching function according to claim 1 or 2, characterized in that, The liquid cathode includes a glass tube with one end open towards the solid anode. A graphite auxiliary electrode is fitted over the glass tube. The solid anode and the graphite auxiliary electrode are connected to a high-voltage power supply.

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