KR0155056B1 - Glow discharge cell - Google Patents

Abstract

The present invention relates to a plasma generating apparatus for a sample that can be used for atomic emission spectroscopy, and in particular to the glow discharge in the cathode tube to make a low-pressure flow gas into a high temperature ionized plasma contained in the sample according to the spectral analysis accordingly The present invention relates to a glow discharge cell of an atomic emission spectrometer capable of performing a trace analysis for each element.

In case of adopting Atomic Absorption Spectroscopy as a conventional sample analyzer, wavelength analysis could not be performed accurately due to the fluctuations of flame and burning temperature. It was difficult to carry equipment because of the need to be provided with a large number of problems, while maintaining a lot of maintenance costs.

The present invention is a positive electrode tube in a state in which the sample is injected into the boat through the opening and closing of the door 330, injected into the syringe through the sample inlet 670, or continuously injected into the cathode tube through the ultrasonic atomizer 270. When the glow discharge is generated in the cathode tube by applying a high voltage to the cathode tube and the cathode, the sample is ionized to generate a plasma, which is capable of analyzing the elements contained in the sample according to the spectral wavelength analysis by the spectrometer. This invention has the advantage of being able to quantitatively and qualitatively accurately.

Description

Glow Discharge Cells in Atomic Emission Spectroscopy

1 is a schematic diagram of an embodiment of a conventional atomic absorption spectroscopy.

2 is a view showing the flame height / relative absorbance according to FIG.

3 is a schematic view of an atomic emission device of a conventional atomic emission spectrometer.

4 is a cross-sectional view of a glow discharge cell (glow discharge cathode tube) inducing flow gas in one direction as an embodiment of the present invention.

5 is a cross-sectional view of an atomizer for inducing flow gas in both directions as another embodiment of the present invention.

Figure 6 is a state of use for syringe injection sample for the embodiment of the present invention.

7 is a state diagram used for continuous sample analysis for an embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

110, 120: macker 121: discharge groove

130: cathode tube 140: anode tube

141 electrode 150 connector

151 electrode 160 power unit

180: heater 190: power supply

210, 220: Macker 211, 221: discharge groove

230: cathode tube 240, 245 anode tube

250, 255: connector 260: power supply

270: atomizer 310: bolt

320: nut 330: door

400: convex lens 610: ball valve

620: needle valve 630: shut off valve

640: flow valve 650: see-through window

660: thermocouple gauge 670: sample inlet

680 flow gas inlet 810 spectrometer

820: Computer

The present invention is to quantitative analysis and qualitative analysis of the components contained in the sample by detecting the spectrum of light by the atoms emitted from the sample to be analyzed at high temperature ionized plasma for air or water pollution analysis In particular, the present invention relates to an atomic emission spectrometer, which uses a direct current power source to induce a glow electric discharge in a hollow cathode tube to induce the release of atoms by making a low-pressure flow gas into a high temperature ionized plasma. The present invention relates to a glow discharge cathode tube, that is, a glow discharge cell of an atomic emission spectrometer, capable of performing a trace analysis for each element contained in a sample based on a spectrum generated therefrom.

With the development of the industry, the problem of environmental pollution is also serious, and the development of an analyzer that accurately analyzes the pollution is urgently required. Therefore, the development of technology capable of analyzing even one atom or molecule is being sought. At the present time, a lot of rapid and accurate methods of analyzing trace elements have been developed and introduced, but still have high sensitivity for analysis without sample preparation in the field. The development of the spectrometer has not been accomplished yet.

In general, the apparatus for constituting the atomic spectrometer is composed of a light source, a glow discharge cell, a monochromator, a detector, and a signal processing and decoding device. These devices vary in their arrangement according to emission, absorption, and fluorescence methods, and vary in composition depending on the atoms to be analyzed. Particularly, in the atomic absorption, emission, and fluorescence analysis, the emission method based on a high energy light source emits light in the ultraviolet or visible region by the excited atoms and ions, unlike the absorption or fluorescence method. It is possible to analyze several elements at the same time by measuring the wavelength and intensity of light through the analysis of the light. The spectrum formation method by electricity, the spectrum formation method by arc light source, the spectrum formation method by spark, DCP and ICP have.

The most widely used atomic spectrometer for atomic analysis is ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometry), which has the advantage of multi-element analysis due to atomic emission induced at high temperature, but it is bulky and economical including maintenance costs. Considering the surface, there is still a sense of distance as a portable spectrometer that can still be analyzed in the field. There was also the introduction of a technology called FANES, which has the advantage of high sensitivity and multi-element analysis using graphite materials and electric discharge, but this technology also had various problems in the conversion to portable.

Figure 1 shows a schematic configuration of an embodiment of the conventional atomic absorption spectroscopy, which is a light source 10 and the combustion furnace 20, burner 30, sprayer 40, detector 50 and It consists of a data system 60.

Light is emitted to the combustion furnace 20 through the transparent window 13 according to the operating voltage applied to the anode 11 and the cathode 12 of the light source 10. At this time, in the combustion furnace 20, the oxidant is injected together with the fuel based on the burner 30 to oxidize, thereby forming a flame, and when the sample s is ejected through the atomizer 40 to atomize, The wall acts like a container.

As such, the absorption of the light emitted from the light source 10 into the atomized sample is changed according to the energy level of the atom, which is detected by the detector 50 by a photodiode, etc. Through the quantitative and qualitative analysis of the sample is possible, as an example of this is shown in Figure 2 the relative absorbance of chromium, magnesium and silver with respect to the height of the flame.

Since the atomic absorption spectroscopy measures the atomic absorption through the flame, the burning temperature is different according to the amount of oxygen introduced into the oxidant, and the background wavelength is changed according to the shaking of the flame, thereby reducing the reliability of the measured value. There is this.

3 is a schematic view of the atomic emission spectrometer of the atomic emission spectrometer which is most widely used. When a high voltage is applied to the coil 80 installed in the light source path 70 to form a magnetic field around the coil 80, When heat is generated and the sample S is sprayed into the coil 80 through the spray device 90, the external electrons are ionized while the sample is burned. When this is detected using a spectrometer, a spectrum having a unique wavelength is formed for each atom. Thus, after preparing and storing standard data based on the measurement and analysis result of the standard sample, the analysis result of the unknown sample is stored. Comparing with, it is possible to perform qualitative and quantitative analysis on unknown samples.

However, spraying the sample requires pretreatment such as removing organic substances, which is not only time-consuming but also difficult and highly likely to involve foreign substances. In addition, there is a problem in that quantitative analysis has a lot of limitations because of poor reproducibility according to the light intensity, and it is difficult to use portable because it is bulky and heavy.

The present invention has been invented to solve the above problems, and in order to be portable and have good sensitivity, for example, a cathode tube is formed of a cylindrical tantalum tube, and a low discharge pressure is induced by using a DC power supply in the cathode tube. (I.e., 1-5 torr) of a flow gas into a hot ionized plasma to induce the release of atoms, which allows microanalysis of the elements contained in the sample, i.e. relatively An inert gas, such as argon, which flows continuously through the cathode tube at high voltage, is ionized by collisions with electrons with high kinetic energy from the cathode tube, and the cations then strike the cathode tube wall again. hot water plasma is formed by causing sputtering. Samples introduced in Zuma are subjected to qualitative and quantitative analysis from ppm to ppb by using the emission spectrum of the sample obtained through this process as each atom is excited and induced to release energy in the form of light. It is an object of the present invention to provide a glow discharge cell of an atomic emission spectrometer that is capable of generating a good reproducible spectrum.

In addition, another object of the present invention is to combine the vacuum pump to the cathode tube to guide the sample and ionization inducer introduced into the cathode tube to the excited state to induce the emission and to continuously analyze the sample by using the flow gas An object of the present invention is to provide a glow discharge cell of an emission spectrometer.

Another object of the present invention is to provide a cylindrical tube of tantalum material having a larger radius than the cathode tube around the cathode tube used as a glow discharge cell to remove moisture from the flow gas and to improve the stability of the plasma generated by the glow discharge. An object of the present invention is to provide a glow discharge cell of an atomic emission spectrometer equipped with an electric heating device.

Hereinafter, the configuration and operation of the present invention will be described in detail with reference to the accompanying drawings.

As a glow discharge cell according to an embodiment of the present invention, as shown in FIG. 4, a long discharge between the macker 110 into which the flow gas is introduced and the macker 120 from which the flow gas is discharged together with the sample to be analyzed. A cylindrical cathode tube 130 is installed and a cylindrical anode tube 140 is installed at a position opposite to the cathode tube 130 with the discharge groove 121 integrally formed in the macker 120 interposed therebetween. The positive electrode and the negative electrode of the power supply unit 160 are respectively connected to the electrode 151 of the anode tube 140 and the electrode 151 installed on the connector 150 for fixing the cathode tube 130 to the macker 110 and 120. Thus, the cathode tube 130 has a structure that can cause a glow discharge.

In addition, as a glow discharge cell according to another embodiment of the present invention, as shown in FIG. 5, a long cylindrical cathode tube 230 is installed between the macker 210 and the macker 220, and each macker 210 ( The cylindrical anode tubes 240 and 245 are respectively provided at positions opposite to both ends of the cathode tubes 230 with the discharge grooves 211 and 221 integrally formed in the 220, respectively, while the cathode tubes ( An atomizer 270 is installed at one central side of the sample 230 to atomize the sample and the flow gas, and the electrodes 241 and 246 and the cathode tube 230 provided at the anode tubes 240 and 245 are installed. The positive electrode and the negative electrode of the power supply unit 260 are connected to the electrodes 251 installed at the connectors 250 and 255 fixedly coupled to the macker 210 and 220, respectively, and the sample flowing into the center of the cathode tube 230 Glow discharge is generated in the cathode tube 230 while the flow gas is dispersed and discharged into the anode tubes 240 and 245. It can be set to the structure so.

In another embodiment of the present invention, a heater 180 is installed around the cathode tubes 130 and 230, and a power source 190 is connected to the heater 180.

In addition, as another embodiment of the present invention, a plurality of bolts 310 and 220 to the macker 120, 220 is installed in the door 300 to be detachable in the outer direction of the macker 120, 220 as a knit (320) It is designed to be able to inject the sample by boat.

4 is a cross-sectional view of a glow discharge cell, that is, a glow discharge cathode tube, which is configured to induce flow gas in one direction as an embodiment of the present invention.

Here, the cathode tube 130 is made of a cylindrical tantalum tube having a diameter of 1/4 or 1/2 and a length of 2-5 cm as a preferred embodiment, and the anode tube 140 is a corrosion resistant metal as a preferred embodiment. Stainless steel is about 5mm thick and consists of the same cylindrical tube as the cathode tube 130.

In addition, each of the macker 110 and 120 is formed of a ceramic material as a preferred embodiment, it is made of a cylindrical valve is formed in the inner side of the inlet groove 111 and the flow gas flowing sample and flow gas in the center Discharge grooves 121 flowing out are formed respectively.

Both ends of the cathode tube 130 are fixed to the macker 110 and 120 based on a connector 150 made of, for example, stainless steel for installing the electrode 151.

On the other hand, the power source 160 is connected to the anode tube 120 and the cathode tube 130 by a power supply unit 160 such that a voltage of about 300-400V is applied so that a glow discharge can be made in the cathode tube 130.

A heater 180 is installed on the circumferential surface of the cathode tube 130 in the horizontal direction, and a voltage is applied from the power supply unit 190 to the heater 180 so that the heater 180 can be heated to about 200 to 300 degrees Celsius as a preferred embodiment. The electric heating device is installed in order to remove moisture of the flow gas flowing into the cathode tube 130 and to improve stability of plasma generated by glow discharge.

The ionizer according to an embodiment of the present invention made as described above is injected into the sample and the flow gas to be analyzed by the inlet groove 111 of the macker 110, as described below, the anode tube 120 through the cathode tube 130 The glow discharge occurs in the cathode tube 130 by the high voltage applied from the power supply unit 160 while being discharged to the side, and the injected sample is ionized to generate plasma.

Figure 5 is another embodiment of the present invention, the basic structure and operation is similar to the embodiment shown in Figure 4, but the sample and the flow gas is injected into the center of the cathode tube 230 is installed in both ends of the cathode tube 230 It is configured to be discharged to the anode tube 240, 245 side, for this purpose is installed in the cathode tube 230 and the center atomizer 270 to atomize the sample and the flow gas, each of the cathode tube 230 The anode tubes 240 and 245 are installed on the outer side of the macker 210 and 220 opposite to the ends, and as described below, the vacuum pumps are coupled to the outer side of the macker 210 and 220 to atomize the device 270. The flow gas injected through) is configured to be dispersed and discharged in both directions, which is configured to generate more stable plasma when the sample injected into the cathode tube 230 is ionized to generate the plasma.

On the other hand, a convex lens 400 is installed at each outer side of the macker 110 and 210 so that a sample is ionized in the cathode tubes 130 and 230 to generate a plasma, which will be described later through the convex lens 400. Is projected to.

6 and 7 show a coupling relationship with peripheral components installed when analyzing a sample using the above embodiment.

FIG. 6 illustrates an ionization device capable of injecting a sample by syringe in the one-way flow gas analysis ionizer shown in FIG. 4.

Here, reference numeral 610 is a ball valve to control the speed of the flow rate through the inflow control of atmospheric pressure, 620 is a needle valve for controlling the injection flow rate of, for example, argon gas as an oxidant injected as a flow gas, 630 is a cathode tube 130 Shut-off valve to open or close the sample to be injected into the cathode tube by maintaining or releasing the vacuum, 640 is a flow meter, 650 is a sight glass, 660 is a thermocouple gauge, 670 is a sample An inlet, 680 is a flow gas inlet, 810 is a spectrometer, and 820 is a data analysis computer.

FIG. 7 illustrates an ionization device equipped with an ultrasonic atomizer 270 in the bidirectional flow gas analysis ionizer shown in FIG. 5 to continuously analyze and inject a sample.

Herein, the components indicated by the same reference numerals as those of FIG. 6 have the same functions as those described with reference to FIG. 6, and detailed descriptions thereof are omitted in order to avoid duplication of description, and the atomizer 270 atomizes the sample to be analyzed. It is installed to be injected into the cathode tube 230.

[Application Example]

As a basic condition for applying the present invention to the sample analysis, the DC power supply of the power supply unit 160 that forms the plasma should be provided, for example, up to about 100 mA, and the flow gas inflow control device has a flow gas of about 50 mL / min. A control device must be used to maintain the flow rate, and the optimum vacuum for plasma generation is about 1.7-2torr. In addition, the sample does not require any special pretreatment. In case of low viscosity liquids, approximately 20 μL is injected directly into the cathode tube. In the case of highly viscous or solid samples, the sample is placed in a cathode boat made of aluminum or tantalum. In particular, when continuous analysis is required, the sample and the flow gas are mixed through the ultrasonic atomizer 270 to continuously be injected into the cathode tube.

1) Syringe injection

First, a sample injection type using a gas chromatography syringe is used as follows. First, the glow discharge cell is vacuumed by using a vacuum pump, and argon, which is a flow gas, is flowed at 50 mL / min. At this time, check whether vacuum is about 1.7torr. Next, the plasma detection photodiode detection system attached to the spectrometer 810 controlled by the computer 820 is operated. The power supply unit 160 or 260 is activated to observe the background spectrum to check the state of the device. After checking the stabilization of the device, the sample is injected into the 20μL through the sample inlet 670. Next, turn on the DC power to 50-100mA and immediately obtain the spectrum and perform sample analysis. Before the next sample injection, observe the background spectrum to confirm the presence of all samples, and then analyze the next sample.

2) Boat-type sample injection

As in the previous syringe injection method, the overall instrument is stabilized. Next, the vacuum is closed by using the vacuum shutoff valve 630 and the pressure is increased to store the sample in the sample boat through the open / close door 330 to be positioned at the center of the cathode tube, and then vacuum. After the vacuum is completed, flow gas is flowed at 50 mL / min. Check the partial pressure at this time. Next, turn on the DC power and slowly raise the current to the proper current level. Emission spectra are obtained and analyzed by spectrometer 810 connected to computer 820. After the experiment is finished, remove the sample boat in reverse order.

3) Continuous sample injection using ultrasonic atomizer

First, as in the previous method, the instrument is stabilized and a high temperature plasma is produced. At this time, the amount of current used is adjusted according to the desired sensitivity. Next, the sample is continuously sent in small amounts (50 mL / min) through the sample inlet of the ultrasonic atomizer 270, and the flow rate of the gas is adjusted in the range considering the shape and temperature of the plasma. Sample analysis is performed by obtaining emission spectra using a photodiode array detector attached to a monochromator of the spectrometer 810 controlled by a computer 820.

As described above, the present invention is to inject the sample to be analyzed by boat-type through the opening and closing of the door 330, the syringe injection through the sample inlet 670, or continuously in the cathode tube through the ultrasonic atomizer 270 In the injected state, when a high voltage is applied to the anode tube and the cathode tube to cause a glow discharge in the cathode tube, the sample is ionized to generate a plasma, and the elements mixed in the sample can be analyzed according to the spectral wavelength analysis by the spectrometer. As a result, it is possible to analyze the cause of air pollution or water pollution, which is the main cause of the pollution environment, and it can be manufactured by hand, so it is not only excellent in the field analysis capability, but also accurate quantitative analysis and qualitative analysis.

Claims (5)

A long cylindrical cathode tube 130 is installed between the macker 110 into which the flow gas is introduced together with the sample to be analyzed and the macker 120 from which the flow gas is discharged, and the discharge groove integrally formed in the macker 120. A cylindrical anode tube 140 is installed at a position opposite to the cathode tube 130 with the 121 disposed therebetween, and the electrode 141 and the cathode tube 130 of the anode tube 140 are macker 110. The positive electrode and the negative electrode of the power supply unit 160 are respectively connected to the electrode 151 installed on the connector 150 fixedly coupled to the 120 to induce a flow discharge in one direction in the cathode tube 130 to cause a glow discharge. Glow discharge cells in atomic emission spectroscopy. A long cylindrical cathode tube 230 is installed between the macker 210 and the macker 220, and the cathode tube (211, 221) integrally formed in each macker 210, 220 is interposed therebetween. Cylindrical anode tubes 240 and 245 are respectively installed at positions opposite to both ends of 230, while the atomizer 270 is configured to atomize a sample and a flow gas at one central side of the cathode tube 230. And electrodes installed on the connectors 250 and 255 for fixing the electrodes 241 and 246 installed on the anode tubes 240 and 245 and the cathode tubes 230 to the macker 210 and 220. Each of the positive and negative electrodes of the power supply unit 260 is connected to the 251, and the sample and the flow gas flowing into the center of the cathode tube 230 are distributed and discharged in both directions through the anode tubes 240 and 245. 230) A glow discharge cell of an atomic emission spectrometer which is capable of causing a glow discharge within the chamber. The glow discharge cell of an atomic emission spectrometer according to claim 1 or 2, wherein the anode tube is made of stainless steel. The glow discharge cell of an atomic emission spectrometer according to claim 1 or 2, wherein the cathode tube is a tantalum tube. The glow discharge cell of an atomic emission spectrometer according to claim 1 or 2, wherein a heater (180) heated by a power supply of a power supply unit (190) is installed around the cathode tube.