KR102420443B1 - Plasma spectrochemical analysis method and plasma spectrochemical analyzer - Google Patents

Abstract

[Task] To provide a simple and highly sensitive plasma spectroscopy analysis method.
[Solutions] The plasma spectroscopic analysis method of the present invention comprises a concentration step of concentrating an analyte in the sample in the vicinity of at least one electrode by applying a voltage to the pair of electrodes in the presence of the sample, and and a detection step of generating plasma by applying a voltage to the electrode and detecting light emission of the analyte generated by the plasma.

Description

Plasma spectroscopic analysis method and plasma spectroscopic analysis apparatus TECHNICAL FIELD

The present invention relates to a plasma spectroscopic analysis method and a plasma spectroscopic analysis apparatus.

As a method of analyzing an analyte in a sample, an analysis method using plasma emission is known. Regarding the above analysis method, Patent Document 1 discloses a method of analyzing a sample using a high-frequency plasma mass spectrometer. Further, Patent Documents 2 and 3 disclose a method of analyzing a sample by generating plasma in a sample using a plasma generating device having a narrow portion and analyzing plasma emission. Further, Patent Documents 4 and 5 disclose a method of analyzing a sample by generating plasma in a liquid sample and analyzing plasma emission.

However, in the method of Patent Document 1, there is a problem that the analysis result changes due to mixing of other substances unless appropriate pretreatment is performed. In addition, in the methods of Patent Documents 2 and 3, when a sample with contaminants is used, and when a foreign material or the like is mixed during pretreatment to reduce the liquid amount of the sample, the contaminants and the foreign material block the narrow part so that the measurement cannot be performed. There was a problem that Moreover, in the method of patent documents 4 and 5, there existed a problem that an analysis sensitivity was low.

Patent Document 1: Japanese Patent Application Laid-Open No. 2009-128315 Patent Document 2: Japanese Patent Laid-Open No. 2011-180045 Patent Document 3: Japanese Patent Laid-Open No. 2012-185064 Patent Document 4: International Publication No. 2006/059808 Patent Document 5: International Publication No. 2011/099247

Accordingly, an object of the present invention is to provide a plasma spectroscopic analysis method that is simple and has high analysis sensitivity.

In order to solve the problem of the present invention, the plasma spectroscopic analysis method of the present invention (hereinafter also referred to as "analysis method") is,

a concentration step of concentrating the analyte in the sample in the vicinity of at least one electrode by applying a voltage to the pair of electrodes in the presence of the sample; and

and a detection step of generating plasma by applying a voltage to the pair of electrodes, and detecting light emission of the analyte generated by the plasma.

The plasma spectroscopy apparatus (hereinafter also referred to as "analysis apparatus") of the present invention includes a pair of electrodes, a container, and a light receiving unit,

The container includes a light-transmitting part,

The pair of electrodes is disposed in the container,

A light receiving unit capable of receiving light emitted by voltage application to the pair of electrodes and light emitted from the analyte through the light transmitting unit is disposed outside the container;

It is characterized in that it is used in the plasma spectroscopic analysis method of the present invention.

The plasma spectroscopic analysis method of the present invention is simple and has high analysis sensitivity. For this reason, according to the plasma spectroscopic analysis method of the present invention, for example, a sample can be analyzed simply and with high sensitivity without pre-processing the sample.

Fig. 1(A) is a schematic perspective perspective view of an analysis apparatus in an embodiment of the analysis apparatus of the present invention, and (B) is a schematic cross-sectional view viewed from the II direction in Fig. 1(A).
Fig. 2 is a graph showing a spectrum in the vicinity of the mercury peak in Example 1 of the present invention.
3 is a graph showing the correlation between the mercury concentration and the count value at the mercury peak in Example 1 of the present invention.
4 is a graph showing a spectrum in the vicinity of the lead peak in Example 2 of the present invention.
5 is a graph showing the correlation between the lead concentration and the count value at the lead peak in Example 2 of the present invention.
6 : is a graph which shows the spectrum of the cadmium peak vicinity in Example 3 of this invention.
Fig. 7 (A) is a graph showing the spectrum when the 10 ppb mercury solution in Example 4 of the present invention is analyzed, and (B) is a 5 ppm mercury solution in the analysis device having a narrow section. It is a graph showing the spectrum when analyzed.

<Plasma spectroscopy analysis method>

As described above, the plasma spectroscopic analysis method of the present invention includes a concentration step of concentrating an analyte in the sample in the vicinity of at least one electrode by applying a voltage to the pair of electrodes in the presence of the sample; and a detection step of generating plasma by applying a voltage to the electrode of , and detecting light emission of the analyte generated by the plasma. The analysis method of the present invention is characterized by including the concentration step and the detection step, and other steps and conditions are not particularly limited.

In general, in order to efficiently analyze the analyte in the sample, for example, the sample is subjected to a pretreatment to reduce the total (total amount) of the sample by concentration, so that the amount of the analyte per unit volume in the total of the sample increased However, according to the present invention, the pretreatment for reducing the total amount of the sample is unnecessary for the following reasons. That is, according to the analysis method of the present invention, in the concentration step, the analyte in the sample is concentrated in the vicinity of at least one electrode by applying a voltage to the pair of electrodes in the concentration step, even if the overall sample is not reduced. That is, the analyte can be locally integrated in the vicinity of the electrode. For this reason, in the subsequent detection step, by generating plasma on the electrode side where the analyte is integrated, it is possible to efficiently analyze the locally high concentration of the analyte. Therefore, according to the analysis method of the present invention, for example, even when the analyte is at a low concentration in the sample to be used, the sample can be easily analyzed with high sensitivity without performing the pre-treatment on the sample prior to analysis, for example. can In addition, the analysis method of the present invention enables efficient analysis by integrating an analyte in the vicinity of at least one electrode and generating plasma on the electrode side. As described above, an analysis device having a narrow portion is not essential. For this reason, for example, as described above, clogging of the analysis apparatus by the contaminants in the sample can be avoided, and it is difficult to be affected by the analysis by contaminants. There is also no need for pretreatment to remove

In the analysis method of the present invention, the sample is, for example, a sample. The specimen may be a liquid specimen or a solid specimen. For the sample, for example, an undiluted solution of the sample may be used as it is as a liquid sample, or a diluted solution obtained by suspending, dispersing or dissolving the sample in a medium may be used as a liquid sample. When the sample is a solid, for example, a diluent in which the sample is suspended, dispersed or dissolved in the medium is preferably used as a liquid sample. The medium is not particularly limited, and examples thereof include water and a buffer solution. The specimen includes, for example, a specimen (sample) derived from a living body, a specimen (sample) derived from the environment, a metal, a chemical substance, a pharmaceutical, and the like. The specimen derived from the living body is not particularly limited, and examples thereof include urine, blood, hair, saliva, sweat, and nails. The blood sample includes, for example, red blood cells, whole blood, serum, plasma, and the like. The living body includes, for example, humans, non-human animals, plants, and the like, and the non-human animals include, for example, mammals other than humans and fish and shellfish. The specimen derived from the environment is not particularly limited, and examples thereof include food, water, soil, air, and air. The food includes, for example, fish food or processed food. The water includes, for example, drinking water, groundwater, river water, seawater, and domestic wastewater.

The analyte is not particularly limited, and examples thereof include metals and chemical substances. The metal is not particularly limited, for example, aluminum (Al), antimony (Sb), arsenic (As), barium (Ba), beryllium (Be), bismuth (Bi), cadmium (Cd), cesium (Cs), gadolinium (Gd), lead (Pb), mercury (Hg), nickel (Ni), palladium (Pd), platinum (Pt), tellurium (Te), thallium (Tl), thorium (Th), tin (Sn), and metals such as tungsten (W) and uranium (U). The chemical substance includes, for example, reagents, pesticides, cosmetics, and the like. The analyte may be, for example, one type or two or more types.

When the analyte is a metal, the sample may contain, for example, a reagent for isolating the metal in the sample. The reagent includes, for example, a chelating agent and a masking agent. The chelating agent is, for example, dithizone, thiopronin, meso-2,3-dimercaptosuccinic acid (DMSA), 2,3-dimercapto-1-propanesulfonate sodium (DMPS), ethylenediaminetetraacetic acid (EDTA), Nitrilotriacetic acid (NTA), ethylenediamine-N,N'-disuccinic acid (EDDS), alpha lipoic acid, etc. are mentioned. In the present invention, "masking" means making the reactivity of the SH group inactive, and can be performed, for example, by chemical modification of the SH group. Examples of the masking agent include maleimide, N-methylmaleimide, N-ethylmaleimide, N-phenylmaleimide, maleimidepropionic acid, iodoacetamide, and iodoacetic acid.

The sample may be, for example, a pH-adjusted sample (hereinafter also referred to as a “pH-adjusted sample”). The pH of the pH-adjusted sample is not particularly limited. The method for adjusting the pH of the sample is not particularly limited, and for example, a pH adjusting reagent such as an alkaline reagent or an acidic reagent can be used.

Examples of the alkaline reagent include alkali and an aqueous solution thereof. The alkali is not particularly limited, and examples thereof include sodium hydroxide, lithium hydroxide, potassium hydroxide, and ammonia. Examples of the aqueous alkali solution include a solution obtained by diluting the alkali with water or a buffer solution. In the aqueous solution of the alkali, the concentration of the alkali is not particularly limited, and is, for example, 0.01 to 5 mol/L.

Examples of the acidic reagent include acids and aqueous solutions thereof. The acid is not particularly limited, and examples thereof include hydrochloric acid, sulfuric acid, acetic acid, boric acid, phosphoric acid, citric acid, malic acid, succinic acid, and nitric acid. The aqueous solution of the acid may be, for example, an acid diluted with water or a buffer solution. In the aqueous solution of the acid, the concentration of the acid is not particularly limited, and is, for example, 0.01 to 5 mol/L.

The electrode is not particularly limited, and examples thereof include a solid electrode, and specific examples thereof include a rod electrode and the like. The material of the electrode is not particularly limited, and any solid conductive material may be used, and for example, it can be appropriately determined according to the type of the analyte. The material of the electrode may be, for example, a non-metal, a metal, or a mixture thereof. When the material of the electrode contains a non-metal, the material of the electrode may contain, for example, one type of non-metal or two or more types of non-metal. Examples of the non-metal include carbon. When the material of the electrode contains a metal, the material of the electrode may contain, for example, one type of metal or two or more types of metals. Examples of the metal include gold, platinum, copper, zinc, tin, nickel, palladium, titanium, molybdenum, chromium, iron, and the like. When the material of the electrode contains two or more kinds of metals, the material of the electrode may be an alloy. Examples of the alloy include brass, steel, Inconel (registered trademark), nichrome, and stainless steel. The pair of electrodes may be, for example, the same material or different materials.

The size of the electrode is not particularly limited, and may be, for example, a size capable of contacting the sample. When the electrode is a rod electrode, the diameter of the electrode is, for example, 0.02 to 50 mm, 0.05 to 5 mm, and the length of the electrode is, for example, 0.1 to 200 mm, 0.3 to 50 mm. The size of the pair of electrodes may be the same or different.

As described above, the concentration step is a step of concentrating the analyte in the sample in the vicinity of at least one electrode by applying a voltage to the pair of electrodes in the presence of the sample. The pair of electrodes is in contact with (in contact with) the sample, for example. In the concentration step, the vicinity of the electrode is not particularly limited, and examples thereof include a range in which plasma is generated in the detection step described later. In the present invention, the vicinity of the electrode includes, for example, the top of the electrode.

In the concentration step, for example, a part of the analyte may be concentrated in the vicinity of the electrode, or all of the analyte may be concentrated in the vicinity of the electrode.

In the concentration step, in the detection step to be described later, it is preferable to set the charge condition of the electrode so that the analyte is concentrated on an electrode used for detection of the analyte, that is, an electrode that generates plasma. The charge condition is not particularly limited. For example, when the analyte has a positive charge, the charge condition may be set so that the electrode generating the plasma has a negative charge. Also, for example, when the analyte has a negative charge, the charge condition may be set so that the electrode generating the plasma has a positive charge.

The concentration of the analyte can be controlled, for example, by voltage. For this reason, a person skilled in the art can appropriately set the voltage at which the concentration occurs (hereinafter also referred to as "concentration voltage"). The concentration voltage is, for example, 1 mV or more and 400 mV or more, and the upper limit thereof is not particularly limited. The concentration voltage may be constant or may fluctuate, for example. In addition, the concentration voltage may be, for example, a voltage at which plasma is not generated.

The time for applying the enrichment voltage is not particularly limited and may be appropriately set according to the enrichment voltage. The time for applying the concentration voltage is, for example, 0.2 to 40 minutes and 1 to 5 minutes. The voltage application to the pair of electrodes may be applied continuously or discontinuously, for example. The discontinuous application may include, for example, pulse application. When the voltage application is discontinuous, the time for applying the enriched voltage may be, for example, the sum of the time during which the enriched voltage is applied, the time for which the enriched voltage is applied and the time during which the enriched voltage is not applied The time may be the sum of the hours.

The voltage can be applied to the electrode by a voltage applying means. The voltage application means is not particularly limited, and for example, a voltage can be applied between the electrodes, and a voltage device or the like can be used as a known means. In the concentration step, the current between the electrodes can be set to, for example, 0.01 to 200 mA, 10 to 60 mA, or 10 to 40 mA.

In the detection step, as described above, plasma is generated by applying a voltage to the pair of electrodes, and the light emission of the analyte generated by the plasma is detected.

The detection step may be performed continuously or discontinuously with the concentration step. In the former case, in the detection step, the detection step is performed simultaneously with the end of the concentration step. In the latter case, in the detection step, the detection step is performed within a predetermined time after the end of the concentration step. The predetermined time is, for example, 0.001 to 1000 seconds or 1 to 10 seconds after the concentration step.

In the detection step, "generating a plasma" means substantially generating plasma, and specifically, in detecting plasma light emission, means generating a plasma exhibiting substantially detectable light emission. As a specific example, it can be said that plasma emission is detectable by a detector of plasma emission.

Substantial generation of plasma can be controlled, for example, by voltage. For this reason, those skilled in the art can appropriately set the voltage (hereinafter also referred to as "plasma voltage") for generating plasma exhibiting substantially detectable light emission. The plasma voltage is, for example, 10 V or more and 100 V or more, and the upper limit thereof is not particularly limited. The voltage at which the plasma is generated is, for example, a voltage that is relatively high compared to the voltage at which the concentration occurs. For this reason, it is preferable that the said plasma voltage is a voltage higher than the said enrichment voltage. The plasma voltage may be constant or may fluctuate, for example.

The time for applying the plasma voltage is not particularly limited and may be appropriately set according to the plasma voltage. The time for applying the plasma voltage is, for example, 0.001 to 0.02 seconds and 0.001 to 0.01 seconds. The voltage application to the pair of electrodes may be applied continuously or discontinuously, for example. The discontinuous application may include, for example, pulse application. When the voltage application is discontinuous, the time for applying the plasma voltage may be, for example, a time during which the plasma voltage is applied once, or may be a sum of time during which the plasma voltage is applied, and the plasma voltage may be applied. It may be a time of the sum of the time during which ? is applied and the time during which the plasma voltage is not applied.

In the detection step, the electrode generating the plasma can be adjusted, for example, by setting the contact area of the pair of electrodes to be different contact areas. Specifically, by making the contact area of one electrode smaller than that of the other electrode, plasma can be generated in electrons. For this reason, in the present invention, the pair of electrodes is a pair of electrodes having a different contact area with the sample, and among the pair of electrodes, the electrode having a smaller contact area with the sample is generated by plasma generation of the analyte. It is preferable that it is an electrode that analyzes the When the contact areas of the pair of electrodes are different, the difference between the contact areas of the pair of electrodes is, for example, 0.001 to 300 cm 2 and 1 to 10 cm 2 . In the present invention, the "contact area" means an area in contact with the sample. The method of adjusting the contact area is not particularly limited, and examples thereof include a method of varying the length of the electrode immersed in the sample, a method of covering a part of the electrode in contact with the sample with an insulating material, and the like. The insulating material is not particularly limited, and examples thereof include resin, silicone, glass, paper, ceramics, rubber, and the like. The resin is, for example, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyethylene terephthalate, polymethacrylate, polyamide, saturated polyester resin, acrylic resin, polybutylene terephthalate (PBT), polyether ether ketone ( PEEK), a thermoplastic resin such as polymethylpentene (eg, registered trademark TPX), an epoxy resin such as a urea resin, a melamine resin, a phenol resin, a fluororesin glass epoxy, and a thermosetting resin such as an unsaturated polyester resin. The silicone includes, for example, polydimethylsiloxane.

The light emission of the plasma generated in the detection step may be detected continuously or may be detected discontinuously, for example. The detection of the light emission includes, for example, detection of the presence or absence of light emission, detection of the intensity of light emission, detection of a specific wavelength, detection of a spectrum, and the like. The detection of the specific wavelength includes, for example, detection of a specific wavelength that occurs when the analysis target emits plasma light. The detection method of the light emission is not particularly limited, and, for example, a known optical measuring device such as a CCD (Charge Coupled Device) or a spectrometer can be used.

The voltage can be applied to the electrode by a voltage applying means. As the voltage applying means, for example, the above description may be referred to. In the detection step, the current between the electrodes can be set to, for example, 0.01 to 100000 mA or 50 to 2000 mA.

The analysis method of the present invention may further include a calculation step of calculating the concentration of the analyte in the sample from the detection result in the detection step. The detection result includes, for example, the intensity of the light emission described above. In the calculation step, the concentration of the analyte can be calculated based on, for example, a detection result and a correlation between the detection result and the concentration of the analyte in the sample. The correlation can be obtained, for example, by plotting the detection result obtained by the analysis method of the present invention and the concentration of the analyte in the standard sample with respect to a standard sample in which the concentration of the analyte is already known. The standard sample is preferably a dilution series of the analyte. By performing calculation in this way, reliable quantitative determination is attained.

In the analysis method of the present invention, the pair of electrodes may be disposed in a container including a light-transmitting part. In this case, in the detection step, the light emission is detected by a light receiving unit arranged to be capable of receiving light emission of the analyte through the light transmitting unit. For the description of the container, the light transmitting unit, the light receiving unit, etc., for example, the description of the analysis apparatus of the present invention described later can be cited.

<Plasma Spectroscopy Device>

As described above, the plasma spectroscopy apparatus of the present invention includes a pair of electrodes, a container, and a light receiving part, the container includes a light transmitting part, the pair of electrodes are disposed in the container, and the outside of the container, A light receiving unit capable of receiving light emitted by voltage application to the pair of electrodes through the light projecting unit is disposed and used in the plasma spectroscopic analysis method of the present invention. The analysis apparatus of the present invention is characterized in that it is used in the above-described analysis method of the present invention, and other configurations and conditions are not particularly limited. According to the analysis apparatus of this invention, the said analysis method of this invention can be implemented simply. For the analysis apparatus of the present invention, for example, the above analysis method of the present invention and description of each other can be used.

An example of the analysis apparatus of this invention is demonstrated with reference to drawings. In addition, in the drawings, for convenience of explanation, the structure of each part may be suitably simplified and shown, and the dimensional ratio of each part etc. may be shown typically unlike reality in some cases.

In FIG. 1, (A) is a schematic perspective perspective view of the analysis apparatus of this embodiment, (B) is a schematic sectional drawing seen from the I-I direction in (A). As shown in FIGS. 1A and 1B , the analysis device 10 of the present embodiment includes a pair of electrodes 1 and 2 , a container 4 , and a light receiving unit 5 , and includes a container ( 4) includes a light-transmitting part 3, and on the outside of the container 4, light emission generated by voltage application to the pair of electrodes 1 and 2, and light emission of the analyte through the light-transmitting part 3 A light receiving unit 5 arranged to receive light is disposed. Further, the electrode 1 is disposed in a direction perpendicular to the bottom surface of the container 4 , and the tip thereof is disposed so as to be in contact with the light transmitting part 3 . The electrode 2 is arranged toward the inside from the side surface of the container 4 . The electrode 1 is covered with an insulating material 6 . In the analysis apparatus 10 of the present embodiment, the sample containing the analyte is introduced into, for example, the cylinder of the container 4 so as to be in contact with the electrodes 1 and 2 . In the present embodiment, the analysis device 10 is a vertical analysis device, but the analysis device 10 is not limited to this embodiment, for example, it may be a horizontal analysis device.

In this embodiment, although the electrode 1 is coat|covered with the insulating material 6 on a part of the surface, the insulating material 6 has an arbitrary structure, and may or may not exist. In addition, in this embodiment, although the electrodes 1 and 2 are arrange|positioned on different surfaces of the container 4, the arrangement position of the electrodes 1, 2 is not specifically limited, For example, it can arrange|position at arbitrary positions. have.

In the present embodiment, the electrode 1 and the light-transmitting part 3 are in contact with each other, but the present invention is not limited to this, for example, the electrode 1 may be disposed apart from the light-transmitting part 3 . The distance between the electrode 1 and the bottom surface of the container 4 is not particularly limited, and is, for example, 0 to 2 cm and 0 to 0.5 cm.

The material of the light-transmitting part 3 is not particularly limited, and may be any material that transmits light generated by voltage application to the pair of electrodes 1 and 2, for example, and can be appropriately set according to the wavelength of the light emission. Examples of the material of the light transmitting part 3 include quartz glass, acrylic resin (PMMA), borosilicate glass, polycarbonate (PC), cycloolefin polymer (COP), methylpentene polymer (TPX (registered trademark)), and the like. . The size of the light-transmitting portion 3 is not particularly limited, and for example, any size capable of transmitting light generated by voltage application to the pair of electrodes 1 and 2 may be sufficient.

In this embodiment, although the container 4 is a cylindrical shape with a bottom, the shape of the container 4 is not limited to this, It is good also as an arbitrary shape. The material of the container 4 is not particularly limited, for example, acrylic resin (PMMA), polypropylene (PP), polyethylene (PE), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polystyrene (PS), etc. can be heard The volume of the container 4 is, for example, 0.3 to 0.5 cm 3 . When the container 4 has a bottomed tubular shape, the diameter of the container 4 is, for example, 0.4 to 50 cm, 1 to 5 cm, and the height thereof is, for example, 0.3 to 50 cm, 0.7 to 2 cm.

The light receiving unit 5 is not particularly limited, and examples thereof include known optical measuring instruments such as CCD and spectrometer. The light receiving unit 5 may be, for example, a transmission means for transmitting the light emission to the optical measuring device disposed outside the analysis device 10 . The transmission means includes, for example, a transmission path such as an optical fiber.

The manufacturing method in particular of the container 4 is not restrict|limited, For example, you may manufacture a molded object by injection molding etc., You may manufacture by forming recesses in base materials, such as a plate. In addition, the manufacturing method in particular of the container 4 etc. is not restrict|limited, For example, lithography, a cutting process, etc. are mentioned.

[Example]

Next, an embodiment of the present invention will be described. In addition, the present invention is not limited by the following examples.

(Example 1)

It was confirmed that mercury can be analyzed with high sensitivity by the analysis method of the present invention.

(1) Plasma spectroscopy apparatus

The analysis apparatus of the said embodiment was prepared. Specifically, a bottomed cylindrical transparent PMMA container (15 mm in height x 10 mm in diameter) was prepared. A quartz glass was placed in the center of the bottom of the vessel. An electrode (1) and an electrode (2) were placed in the container. The electrode 1 was disposed in a direction perpendicular to the bottom of the container. And it arrange|positions so that the front-end|tip of the electrode 1 may contact with the quartz glass of the bottom part of the said container. As the electrode 1, a brass rod having a diameter of 0.12 mm was used. The electrode 1 exposed 0.3 mm from the tip and insulated the other area|region was used. The electrode 2 was disposed in a direction perpendicular to the electrode 1 and toward the inside from the side surface of the container. As the electrode 2, a carbon electrode rod having a diameter of 2.5 mm was used. Further, an optical fiber was disposed so as to face the tip of the electrode 1 through the quartz glass. As the optical fiber, a single-core optical fiber having a diameter of 400 µm was used. In addition, the said optical fiber was connected to the spectrometer (self-prepared) of the concave grating system.

(2) Plasma spectroscopic analysis

Mercury chloride was dissolved in 0.3 mL of 0.1 mol/L nitric acid aqueous solution so as to be 100 ppb, and this was used as a mercury sample. Next, the mercury sample was introduced into the vessel of the analysis device. Then, between the electrode 1 and the electrode 2, a voltage is applied under the following concentration conditions so that the electrode 1 becomes the cathode (cathode) and the electrode 2 becomes the anode (anode), and the electrode ( The mercury was concentrated in the vicinity of 1).

(Condense conditions)

Applied voltage: repetition of 30 V and 0 V

Pulse width: 50 μs

Duty: 99%

Application time: 500 ms

Number of applications: 250 times at 1 s intervals

Immediately after the concentration, between the electrode 1 and the electrode 2, a voltage and a current are applied under the following plasma generation conditions so that the electrode 1 becomes an anode and the electrode 2 becomes a cathode, The light emission intensity (count value) at each wavelength of plasma light emission was measured. In the control (comparative example), the spectrum of the generated plasma emission was measured in the same manner except that the above-mentioned concentration was not performed.

(Conditions for generating plasma)

Applied voltage: repetition of 150 V and 0 V

Pulse width: 50 μs

Duty: 80%

Application time: 100 ms

The results are shown in FIG. 2 . 2 is a graph showing a spectrum in the vicinity of a mercury peak. In Fig. 2, the horizontal axis represents the wavelength, and the vertical axis represents the emission intensity (count value). In addition, in FIG. 2, a solid line shows the result of an Example, and a broken line shows the result of a comparative example. As shown in FIG. 2, compared with the comparative example, the count value increased in the vicinity of 253.65 nm which is the wavelength of plasma emission characteristic of mercury. In addition, although a peak (mercury peak) is observed at 253.88 nm in FIG. 2, this is because the measurement error of the said spectrometer is included. From these results, it can be seen that the analytical method of the present invention has higher analytical sensitivity than the analytical methods of Patent Documents 4 and 5 in which the concentration is not performed.

(3) Plasma spectroscopic analysis at different analyte concentrations

The count value of the mercury peak was measured in the same manner as in Example 1 (2), except that mercury chloride was dissolved in 0.3 mL of 0.1 mol/L nitric acid aqueous solution to a predetermined concentration (10 ppb, 50 ppb, 100 ppb).

The results are shown in FIG. 3 . 3 is a graph showing the correlation between the mercury concentration and the count value at the mercury peak. In Fig. 3, the horizontal axis indicates the concentration of mercury, and the vertical axis indicates the emission intensity (count value). As shown in FIG. 3 , the count value increased in a concentration-dependent manner of mercury. From these results, it can be seen that, according to the analysis method of the present invention, analytes can be analyzed in a wide range of concentrations.

(Example 2)

It was confirmed that lead in a urine specimen can be analyzed with high sensitivity by the analysis method of the present invention.

(1) Plasma spectroscopic analysis

Lead was dissolved in the urine sample to a concentration of 100 ppb. Next, the powder of lithium hydroxide was added so that it might become 0.2 mol/L lithium hydroxide. Then, in the same manner as in Example 1 (2), except that the lead sample was used instead of the mercury sample, the spectrum of the generated plasma emission was measured. In the control (comparative example), the spectrum of the generated plasma emission was measured in the same manner except that the above-mentioned concentration was not performed.

The results are shown in FIG. 4 . 4 is a graph showing a spectrum in the vicinity of a lead peak. In Fig. 4, the horizontal axis represents the wavelength, and the vertical axis represents the emission intensity (count value). In addition, in FIG. 4, a solid line shows the result of an Example, and a broken line shows the result of a comparative example. As shown in Fig. 4, compared with the comparative example, the count value increased in the vicinity of 368.34 nm, which is the wavelength of plasma emission peculiar to lead. In addition, in FIG. 4, although a peak (lead peak) is observed at 368.52 nm, this is because the measurement error of the said spectrometer is included. From these results, it can be seen that the analysis method of the present invention has a higher analysis sensitivity than the analysis methods of Patent Documents 4 and 5 in which the concentration is not performed.

(2) Plasma spectroscopic analysis at different analyte concentrations

Lead nitrate was dissolved in a urine specimen to a predetermined concentration (10 ppb, 50 ppb, 100 ppb). Next, the lead peak count was measured in the same manner as in Example 1 (2), except that a lead sample to which lithium hydroxide powder was added so as to obtain 0.2 mol/L lithium hydroxide was used instead of the mercury sample.

The results are shown in FIG. 5 . 5 is a graph showing the correlation between the lead concentration and the count value at the lead peak. In Fig. 5, the horizontal axis indicates the concentration of lead, and the vertical axis indicates the emission intensity (count value). As shown in FIG. 5 , the count value increased in a lead concentration-dependent manner. From these results, it can be seen that, according to the analysis method of the present invention, analytes can be analyzed in a wide range of concentrations. Moreover, it turns out that the analysis method of this invention can analyze the said analyte also in the urine sample which is a sample containing contaminants.

(Example 3)

It confirmed that cadmium could be analyzed sensitively by the analysis method of this invention.

The spectra of generated plasma emission were measured in the same manner as in Example 2(1) except that a cadmium sample in which cadmium was dissolved to 1 ppm in a 0.2 mol/L lithium hydroxide solution was used instead of the lead sample. In the control (comparative example), the spectrum of the generated plasma emission was measured in the same manner except that the above-mentioned concentration was not performed.

The results are shown in FIG. 6 . 6 : is a graph which shows the spectrum of cadmium peak vicinity. In Fig. 6, the horizontal axis represents the wavelength, and the vertical axis represents the emission intensity (count value). In addition, in FIG. 6, a solid line shows the result of an Example, and a broken line shows the result of a comparative example. As shown in FIG. 6, compared with the comparative example, the count value increased in the vicinity of 228.80 nm which is the wavelength of plasma emission of cadmium. In addition, although a peak is observed at 228.9 nm in FIG. 6, this is because the said spectrometer measurement error is included. From these results, it can be seen that the analysis method of the present invention has a higher analysis sensitivity than the analysis methods of Patent Documents 4 and 5 in which the concentration is not performed.

(Example 4)

It was confirmed that mercury can be analyzed with high sensitivity by the analysis method of the present invention.

The spectra of generated plasma emission were measured in the same manner as in Example 1 (2), except that mercury chloride was dissolved in 0.3 mL of 0.1 mol/L nitric acid aqueous solution to a concentration of 10 ppb to obtain a mercury sample. In Control 1 (Comparative Example 1), the spectra of generated plasma emission were measured in the same manner except that the above-mentioned concentration was not performed.

In Control 2 (Comparative Example 2), mercury was dissolved in 0.3 mL of 0.1 mol/L nitric acid aqueous solution to a concentration of 5 ppm as the mercury sample. In Control 2, instead of the plasma spectroscopic analyzer, a resin cell having a narrow section (LepiCuve, manufactured by Microemission Co., Ltd.) and a plasma spectroscopic analyzer for measuring the resin cell (Handy Elemental Analysis MH-500, The spectrum of the plasma emission generated in the said mercury sample was measured according to the attached protocol using the Microemission Co., Ltd. product). In Control 3 (Comparative Example 3), 0.1 mol/L aqueous nitric acid solution was used instead of the mercury sample, and the resin cell and the corresponding plasma spectroscopy apparatus were used, except that the plasma emission was generated in the same manner as in Control 2. The spectrum was measured.

The result is shown in FIG. 7(A) is a graph showing a spectrum when a 10 ppb mercury solution is analyzed, and (B) is a graph showing a spectrum when a 5 ppm mercury solution is analyzed in an analysis device with a narrow portion It is a graph. 7A and 7B , the horizontal axis indicates the wavelength, and the vertical axis indicates the emission intensity (count value). In addition, in FIG. 7A, a solid line shows the result of Example, and a broken line shows the result of Comparative Example 1. In addition, in FIG. In FIG. 7B , the solid line shows the result of Comparative Example 2, and the broken line shows the result of Comparative Example 3. As shown in FIG. 7(A), compared with Comparative Example 1, the count value increased by about 900 counts in the mercury peak. In addition, as shown in Fig. 7B, in Comparative Example 2, compared to Comparative Example 3, the count value increased by about 500 counts at 253.00 nm, which is the wavelength of mercury-specific plasma emission, around 253.65 nm. Moreover, although a peak is observed at 253.00 nm in FIG.7(B), this is because this includes the measurement error of the plasma spectroscopy apparatus for the said resin cell measurement. From these results, it is understood that the analysis method of the present invention can obtain about twice the count value even at a mercury concentration of 1/500 compared to the method using a resin cell having a narrow portion. That is, it turns out that the analytical sensitivity of the analysis method of this invention is high compared with the analysis method of patent documents 2 and 3.

As mentioned above, although this invention was demonstrated with reference to embodiment and an Example, this invention is not limited to the said embodiment and Example. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

This application claims priority on the basis of Japanese Patent Application No. 2015-003795 for which it applied on January 13, 2015, and takes in all the indications here.

The plasma spectroscopic analysis method of the present invention is simple and has high analysis sensitivity. For this reason, according to the plasma spectroscopy analysis method of this invention, for example, a sample can be analyzed simply and highly sensitively, without pre-processing a sample. For this reason, this invention is very useful, for example for the analysis of elements etc. using plasma generation.

1, 2: Electrode 3: Transmitting part
4: container 5: light receiving part
6: insulating material 10: analysis device

Claims (12)

A concentration step of concentrating the analyte in the sample in the vicinity of the first electrode having a smaller area in contact with the liquid sample than the second electrode by applying a voltage to the first electrode and the second electrode immersed in the liquid sample , and
a detection step of generating plasma in the first electrode by applying a voltage to the first electrode and the second electrode, and detecting light emission of the analyte generated by the plasma,
A polarity of the first electrode in the concentration step is different from a polarity of the first electrode in the detection step. The plasma spectroscopy method of claim 1, wherein the voltage in the detection process is higher than the voltage in the enrichment process. The method of claim 1, wherein the voltage in the enrichment process is 1 mV or more. The plasma spectroscopy method according to claim 1, wherein the voltage in the detection process is 10 V or more. The method of claim 1, wherein the first electrode and the second electrode are disposed in a container;
The container includes a light-transmitting part,
A plasma spectroscopic analysis method in which a light receiving unit capable of receiving light emitted from the analyte through the light transmitting unit is disposed outside the container. The method of claim 1 , wherein the analyte is a metal. 7. The method of claim 6 wherein the metal is aluminum, antimony, arsenic, barium, beryllium, bismuth, cadmium, cesium, gadolinium, lead, mercury, nickel, palladium, platinum, tellurium, thallium, thorium, tin, tungsten and uranium. Plasma spectroscopy method of at least one metal selected from the group consisting of. The plasma spectroscopy method of claim 1, wherein the liquid sample is at least one of a biological sample and an environment-derived sample. The method of claim 8, wherein the biological sample is at least one selected from the group consisting of urine, blood, hair, saliva, sweat, and nails. The method of claim 8 , wherein the environment-derived sample is at least one selected from the group consisting of food, water, soil, and air. It includes a first electrode and a second electrode, a container and a light receiving unit,
The container includes a light-transmitting part,
the first electrode and the second electrode are disposed in the vessel;
A light receiving unit capable of receiving light emitted by the application of a voltage to the first electrode and the second electrode through the light transmitting unit is disposed on the outside of the container,
It is used for the plasma spectroscopy method in any one of Claims 1-10, The plasma spectroscopy apparatus characterized by the above-mentioned. delete

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