JP4585267B2 - Trace analysis method - Google Patents

Description

The present invention relates to a microanalysis method for measuring an analyte to be detected by an electrochemical measurement method .

  Recently, there is a very high need for techniques for diagnosis and analysis at low cost in a short time for medical diagnosis, monitoring of environmental pollutants such as trace amounts of environmental hormones in the air, water and soil, dioxins, and food safety inspections. It has become to.

  In order to perform such a measurement easily, it is necessary to be able to perform analytical detection with high sensitivity using a very small amount of sample. For this purpose, GC-MS, LC-MS, ICP-MS, which are separated by capillary gas chromatography (CGC), capillary liquid chromatography (ILC), induction plasma (ICP), etc., and detected by a mass spectrometer (MS) Have been widely used as a method that can be analyzed with a small amount and high sensitivity.

However, since these devices are expensive and large-scale devices, it is very expensive to easily carry or install them in a desired place, and recently, electrochemical measurement methods have been widely adopted.

  The electrochemical measurement method is an extremely simple measurement method that can detect the analyte to be detected as long as there is an electrode for measurement and a system that applies voltage and current. Since it can be manufactured at a low cost, it has a possibility of being widely used in medical diagnosis and environmental diagnosis sites.

For example, it reacts with a mediator that reacts in response to the action of an enzyme present in the cell membrane of a bacterium to be detected (including viable bacteria) present in a sample, and the reacted mediator is detected or quantified by an electrochemical technique. Thus, a bacteria detection method (for example, see Patent Document 1) characterized by detecting or quantifying the bacteria has been proposed.
JP 2000-283945 A

  However, the measurement of trace substances using the electrochemical measurement method has a drawback that sufficient sensitivity may not always be obtained depending on the type of analyte to be detected and the structure of the electrode used.

  In order to solve such problems, if the sample is concentrated in the pre-detection stage, it is possible to detect with high sensitivity even when using an electrochemical sensor that cannot normally obtain high sensitivity. Become.

  In fact, in the detection method described in the above-mentioned Patent Document 1, in order to improve the quantification accuracy, a process of concentrating with a membrane separation device or a centrifuge device before detection or quantification by an electrochemical method is proposed. Yes.

  However, including such a concentration or separation step in the previous step is not applicable to a simple electrochemical analyzer because the number of steps is increased and the apparatus is complicated.

  An object of the present invention is to provide a microanalysis method capable of concentrating a sample to be detected very easily and, as a result, accurately detecting the sample to be detected in view of the above-mentioned drawbacks.

The microanalysis method according to claim 1 is a step of evaporating and drying the solvent in a state where the detection solvent solution containing the analyte to be detected is in contact with the electrode part for electrochemical measurement of the electrode element for electrochemical measurement. Electrochemical measurement can be performed by immersing the electrochemical measurement electrode part of the electrochemical measurement electrode element in a liquid and applying a voltage higher than the oxidation potential of the detected analyte to the electrochemical measurement electrode part. It consists of the process performed by the measuring method.

  The first step is a step of evaporating and drying the solvent in a state where the detection solvent solution containing the sample to be detected is in contact with the electrode portion for electrochemical measurement of the electrode element for electrochemical measurement. The electrode element for electrochemical measurement is preferably composed of an electrode part for electrochemical measurement and a non-electrode part, and the solvent is volatilized while the detection solvent solution containing the analyte to be detected is in contact with the electrode part for electrochemical measurement. dry.

  The material for the electrode part for electrochemical measurement is not particularly limited, but it is necessary that the material is not subject to corrosion or oxidation by the analyte to be detected or its solvent, dispersion medium, dissolved oxygen or the like.

  In general, an electrode of any material adsorbs hydrogen ions on the surface of the electrode on the negative potential side and forms an oxygen film on the positive potential side. Since the conductivity is different, this state is not preferable as an electrode used for electrochemical measurement.

  Therefore, it is better that the potential difference (= potential window) between the potential for forming the hydrogen ion film and the potential for forming the oxide film is wider, and it is preferable to use a metal species satisfying such a condition as an electrode material. Platinum, gold, mercury, silver, bismuth and the like. Although not a metal, carbon is also preferably used because of its wide potential window.

  The structure of the electrode element for electrochemical measurement is not particularly limited, and examples thereof include an electrode in which the electrode material is laminated on a substrate such as glass, and the electrode area is reduced, that is, generally with a microelectrode. By adopting the so-called structure, it is possible to speed up the material diffusion on the electrochemical measurement electrode part of the analyte to be detected.

  In addition, as a method for laminating the electrode material, any conventionally known method may be adopted, and examples thereof include vapor deposition, sputtering, CVD, electrolytic plating, electroless plating, screen printing, and the like, and an electrode with good accuracy and purity. Vapor deposition and sputtering are preferable for obtaining the film, and plating and screen printing are preferable for easily manufacturing at low processing costs.

  The method for bringing the detection solvent solution containing the sample to be detected into contact with the electrode part for electrochemical measurement of the electrode element for electrochemical measurement is not particularly limited. For example, the sample to be detected is placed on the surface of the electrode part for electrochemical measurement. And a method of dropping a detection solvent solution containing the above by a dropoid, a pipette or the like.

  In addition, a conventionally known arbitrary method may be adopted as a method for drying the solvent, for example, a method of heating with a heater, a method of blowing hot air, etc. It is preferable to dry the solvent by heating with a heater.

  The electrode part for electrochemical measurement of the electrode element for electrochemical measurement is obtained by evaporating and drying the solvent in a state where the detection solvent solution containing the sample to be detected is in contact with the electrode part for electrochemical measurement of the electrode element for electrochemical measurement. A film containing the analyte to be detected is formed on the surface of the film.

  A coating containing the analyte to be detected may also be formed on the surface of the non-electrode portion, but the electrochemical measurement method is used to quantify the analyte to be detected using the electrode element for electrochemical measurement on which the coating containing the analyte is formed. For the measurement, it is preferable that the film containing the sample to be detected is formed only on the electrode portion.

  Therefore, the surface of the non-electrode part is preferably water-repellent so that a film containing the specimen to be detected is mainly formed on the electrode part for electrochemical measurement, and the part to be detected is subjected to the water-repellent process. The contact angle with the detection solvent solution containing the specimen is more preferably 90 degrees or more.

  As the water repellent treatment method, any conventionally known method may be employed. For example, a method of coating a fluororesin layer on the treated surface, a monomolecular film of an alkyl ketene dimer (LB film, self-assembled film, etc.) And a method of forming a single particle film of water-repellent fine resin particles such as polytetrafluoroethylene (preferably having a diameter of 10 μm or less, preferably about 1 μm).

  The next step is a step of immersing the electrochemical measurement electrode part of the dried electrochemical measurement electrode element in a liquid. The liquid may be any liquid that allows current to flow. For example, an aqueous electrolyte solution containing an electrolyte such as potassium hydroxide or potassium nitrate is preferably used. Also, aliphatic hydrocarbons, aromatic hydrocarbons, chlorinated hydrocarbons, ethers, acetone, nitromethane, nitrobenzene, acetonitrile, dimethylformamide, pyrrolidone, hydrogen fluoride, methanol, ethanol and other solvents such as potassium hydroxide and potassium nitrate An electrolyte may be contained.

  The last step is a step in which the analyte is quantified by the electrochemical measurement method by applying a voltage higher than the oxidation potential of the analyte to be detected to the electrode electrode for electrochemical measurement of the electrode element for electrochemical measurement.

  In the above quantification, the counter electrode and / or the reference electrode is immersed in a liquid, and a voltage higher than the oxidation potential of the analyte to be detected is applied to the electrochemical measurement electrode part of the electrochemical measurement electrode element to perform electrochemical measurement. preferable.

  The material of the counter electrode is not particularly limited, but is required to be a material that is not subject to corrosion or oxidation by the analyte to be detected or its solvent, dispersion medium, dissolved oxygen, or the like, and platinum is preferably used.

  The reference electrode needs to have a stable potential. Examples thereof include a hydrogen electrode, a saturated calomel electrode (= mercury / mercury chloride electrode), a silver / silver halide electrode, and the like. From the viewpoint of processing cost, a silver / silver halide electrode such as a silver / silver chloride electrode and a silver / silver iodide electrode is preferable, and a silver / silver iodide electrode having excellent measurement sensitivity is more preferable.

  When a silver / silver halide electrode is used as a reference electrode, the liquid contains the same halogen ions as the silver halide halogen so that the silver halide of the silver / silver halide electrode does not elute into the liquid. Is preferred. That is, the silver / silver chloride electrode preferably contains chlorine ions, and the silver / silver iodide electrode preferably contains iodine ions. The concentration is not particularly limited, but is generally preferably 0.01 to 0.5 M (mmol / l).

  In order to contain halogen ions in the liquid, chlorine gas, hydrogen chloride, sodium chloride, potassium chloride, silver chloride, sodium bromide, potassium bromide, iodine, silver bromide, sodium iodide, potassium iodide, iodine A compound such as silver halide may be dissolved. Furthermore, among these, since silver chloride, silver bromide and silver iodide are silver compounds, elution of silver halide in the silver / silver halide electrode can be suppressed more efficiently.

  As the electrochemical measurement method, any conventionally known method may be adopted, and examples thereof include a voltammetry method, a stripping voltammetry method, an amperometry method, a potentiometry method, and a coulometry method. The amperometry method and the coulometry method are preferred, and when the analyte to be detected is a heavy metal, the stripping voltammetry method is preferred.

  Examples of the voltage and current waveforms applied in these electrochemical measurement methods include a pulse wave, a differential pulse wave, a triangular wave, and a step wave as appropriate.

  The voltammetry method is a method in which a potential is applied between an electrode portion for electrochemical measurement of an electrode element for electrochemical measurement and a counter electrode, and the relationship between the current flowing at that time and the applied potential is examined. The electrode used in the voltammetry method is desirably a three-electrode system in which a reference electrode is added to the electrode for electrochemical measurement of the electrode element for electrochemical measurement and a counter electrode. Since the reference electrode always shows a constant potential regardless of the magnitude of the applied potential, using the reference electrode as a reference is useful for determining the absolute value of the potential applied to the electrochemical measurement electrode.

  The stripping voltammetry method is a method of applying an electrode potential for electrochemical measurement of an electrode element for electrochemical measurement by applying a potential suitable for reduction of the analyte to be measured. In this method, the reduced form of the analyte to be detected is concentrated, and then a potential suitable for oxidation of the analyte to be detected is applied to desorb the reduced substance of the analyte to be detected from the electrode for electrochemical measurement. At this time, since desorption occurs at a potential specific to the sample to be detected, the type of the sample to be detected can be specified, and the concentration of the sample to be detected can be specified by measuring the current generated simultaneously. .

  Since the method includes the step of concentrating the reduced substance of the analyte to be detected on the electrochemical measurement electrode portion of the electrochemical measurement electrode element, analysis with higher sensitivity is possible. Also in this measurement method, in order to know the absolute potential, a three-electrode system including an electrochemical measurement electrode part, a counter electrode, and a reference electrode of the electrochemical measurement electrode element is desirable.

  The amperometry method is a measurement method in which a constant potential is applied between an electrode portion for electrochemical measurement and a counter electrode of an electrode element for electrochemical measurement, and a change in current with time is monitored. Also in this measurement method, in order to know the absolute potential, a three-electrode system including an electrochemical measurement electrode part, a counter electrode, and a reference electrode of the electrochemical measurement electrode element is desirable.

  The potentiometry method is a measurement method in which an appropriate current is passed between the electrode portion for electrochemical measurement and the counter electrode of the electrode element for electrochemical measurement, and the potential change at that time is monitored. Also in this measurement method, in order to know the absolute potential, a three-electrode system including an electrochemical measurement electrode part, a counter electrode, and a reference electrode of the electrochemical measurement electrode element is desirable.

  In the coulometry method, a substance to be detected is electrodeposited by applying a potential between the electrode part for electrochemical measurement of the electrode element for electrochemical measurement and a counter electrode, and the amount of coulomb is measured.

In the microanalysis method according to claim 8, the detection solvent solution containing the analyte to be detected is in contact with the electrochemical measurement electrode of the electrochemical measurement electrode element and the reference electrode capable of determining the potential of the electrochemical measurement electrode. In the state, while applying a potential at which the analyte to be detected can be deposited from the detection solvent solution on the electrochemical measurement electrode to the electrochemical measurement electrode, the solvent is volatilized to reduce the volume of the detection solvent solution and the detection The method is characterized by comprising a step of quantifying a specimen by an electrochemical measurement method.

Hereinafter, the microanalysis method according to claim 8 will be described, but differences from the microanalysis method according to claim 1 will be described . As described above, the electrode element for electrochemical measurement preferably comprises an electrode part for electrochemical measurement and a non-electrode part.

  The first step is a detection solvent solution containing the analyte to be detected in a reference electrode capable of determining the potential of the electrochemical measurement electrode part of the electrochemical measurement electrode element and the electrochemical measurement electrode part of the electrochemical measurement electrode element Is applied to the electrode part for electrochemical measurement of the electrode element for electrochemical measurement, in such a state that the analyte can be precipitated from the detection solvent solution on the electrode part for electrochemical measurement of the electrode element for electrochemical measurement. In the process of volatilizing the solvent and reducing the volume of the detection solvent solution, the analyte to be detected is deposited on the electrochemical measurement electrode portion of the electrode element for electrochemical measurement and collected. Volume is reduced.

  The electrochemical measurement electrode part and the reference electrode of the electrochemical measurement electrode element may be separate from each other, or the reference electrode may be formed on the electrochemical measurement electrode element. In order to form the reference electrode on the electrode element for electrochemical measurement, for example, a conductive material such as platinum or bismuth constituting the electrode part for electrochemical measurement on a substrate such as a glass plate and silver or mercury constituting the reference electrode. The method of laminating | stacking electrically conductive materials, such as sputtering, by lamination methods, such as sputtering and vapor deposition, respectively, is mentioned.

  In addition, when the reference electrode is formed on the electrode element for electrochemical measurement, it is a point electrode so that the state in contact with both electrodes is maintained even if the detection solvent solution containing the analyte to be detected is reduced. A reference electrode which is a circumferential electrode is formed around the electrode part for electrochemical measurement via a non-electrode part, or is a circumferential electrode around the reference electrode which is a point electrode via a non-electrode part An electrode part for electrochemical measurement is preferably formed.

  Furthermore, a water-repellent treatment is performed so that the detection solvent solution containing the majority of the analyte to be detected is in contact with the electrode portion for electrochemical measurement and the reference electrode, and the detection solvent solution containing the analyte to be detected is not in contact with the non-electrode portion. The contact angle with the detection solvent solution containing the analyte to be detected in the portion subjected to the water repellent treatment is more preferably 90 degrees or more. The water repellent treatment method is as described above.

  The reference electrode needs to have a stable potential. Examples thereof include a hydrogen electrode, a saturated calomel electrode (= mercury / mercury chloride electrode), a silver / silver halide electrode, and the like. From the viewpoint of processing cost, a silver / silver halide electrode such as a silver / silver chloride electrode and a silver / silver iodide electrode is preferable, and a silver / silver iodide electrode having excellent measurement sensitivity is more preferable.

  Although the solvent is volatilized and the volume of the detection solvent solution decreases, all the solvent may be volatilized and dried, or the solvent may remain.

  When the solvent remains, the sample to be detected may be quantified by bringing the counter electrode into contact with the detection solvent solution in the next step.

In this case, when a silver / silver halide electrode is used as the reference electrode, the detection solvent solution is the same as the halogen of the silver halide so that the silver halide of the silver / silver halide electrode does not elute into the detection solvent solution. It preferably contains a halogen ion. That is, the silver / silver chloride electrode preferably contains chlorine ions, and the silver / silver iodide electrode preferably contains iodine ions .

  In the case of drying, as described above, the electrochemical measurement electrode part of the electrochemical measurement electrode element, the reference electrode, and the counter electrode may be immersed in the liquid to perform electrochemical measurement. In this case, a new reference electrode may be prepared, and electrochemical measurement may be performed using the new reference electrode and the electrochemical measurement electrode portion of the electrochemical measurement electrode element as a counter electrode.

At this time, when a silver / silver halide electrode is used as the reference electrode, as described above, the liquid is the same as the halogen of the silver halide so that the silver halide of the silver / silver halide electrode does not elute into the liquid. It preferably contains a halogen ion. That is, the silver / silver chloride electrode preferably contains chlorine ions, and the silver / silver iodide electrode preferably contains iodine ions .

The configuration of the microanalysis method according to claim 1 is as described above, and in a state where the detection solvent solution containing the analyte to be detected is in contact with the electrode element for electrochemical measurement (electrode part for electrochemical measurement), the solvent is used. After volatilization and drying, the electrochemical measurement electrode part of the dried electrochemical measurement electrode element is immersed in a liquid, and a voltage higher than the oxidation potential of the analyte to be detected is applied to the electrochemical measurement electrode part of the electrochemical measurement electrode element Since the sample to be detected is quantified by applying, the sample to be detected can be concentrated very easily, and as a result, the sample to be detected can be detected with high accuracy.

The electrochemical analysis method according to claim 1, wherein the electrochemical measurement electrode element comprises an electrochemical measurement electrode part and a non-electrode part, and the non-electrode part is subjected to a water repellent treatment. As a result, a larger amount of the detection solvent solution is dried at the electrode portion, and the analyte to be detected can be detected with higher accuracy.

In the microanalysis method according to the third aspect , since the reference electrode is immersed in a liquid and the sample to be detected is quantified by the electrochemical measurement method, the sample to be detected can be detected with higher accuracy.

  In addition, by using a silver / silver halide electrode, particularly a silver / silver iodide electrode as a reference electrode, the analyte can be detected more accurately, and the halogen of the silver / silver halide electrode can be detected in the liquid. In the presence of the same halogen ion, the analyte to be detected can be detected with higher accuracy. Further, among the halogens, iodine is difficult to be dissolved in the liquid, so that contamination of the electrode portion for electrochemical measurement can be suppressed, and the analyte to be detected can be detected with high accuracy.

The configuration of the microanalysis method according to claim 8 is as described above, and the potentials of the electrode portion for electrochemical measurement of the electrode element for electrochemical measurement and the electrode portion for electrochemical measurement of the electrode element for electrochemical measurement are determined. Electrochemical measurement of the potential at which the analyte can be deposited from the detection solvent solution on the electrode for electrochemical measurement of the electrode element for electrochemical measurement in a state where the detection solvent solution containing the analyte is in contact with the reference electrode Since the solvent is volatilized and the volume of the detection solvent solution is reduced while being applied to the electrode part for electrochemical measurement of the electrode element for measurement, the sample to be detected is quantified. It is collected on the electrode part for electrochemical measurement of the electrode element, and the analyte to be detected can be detected with high accuracy.

Microanalysis method of claim 9, wherein, in the electrochemical measurement method according to claim 9, wherein the electrochemical measuring electrode device is made of an electrochemical measuring electrode portion and the non-electrode portion, the non-electrode portion is water repellent As a result, a larger amount of the detection solvent solution is dried by the electrochemical measurement electrode section, and the analyte to be detected can be detected more accurately.

The microanalytical method according to claims 10 to 13 can detect the analyte to be detected more accurately by using a silver / silver halide electrode, particularly a silver / silver iodide electrode as a reference electrode, In the presence of the same halogen ion as the halogen of the silver / silver halide electrode, the analyte to be detected can be detected with higher accuracy.

The microanalysis method according to claim 14 is the microanalysis method according to claim 2 or 9 , wherein the contact angle of the water-repellent-treated portion with the detection solvent solution containing the sample to be detected is 90 degrees or more. Many detection solvent solutions are dried by the electrode part for electrochemical measurements, and furthermore, the analyte to be detected can be detected with high accuracy.

In the microanalysis method according to claim 15 , since the volatilization of the solvent is performed by a heater installed in the vicinity of the liquid contact part, the solvent can be volatilized more efficiently and the analyte to be detected can be concentrated efficiently. As a result, the analyte can be detected with high accuracy.

In the microanalysis method according to the sixteenth aspect, since the quantification of the detected sample is an amperometry method, a voltammetry method or a coulometry method, the detected sample can be detected with high accuracy.

  In addition, in the microanalysis method of the present invention, heavy metals can be detected with high accuracy, and particularly with the stripping voltammetry method.

  Next, examples of the present invention will be described with reference to the drawings. However, the present invention is not limited to these examples.

Example 1
FIG. 1 is a plan view showing an example of an electrode element for electrochemical measurement, and FIG. 2 is a diagram in which a detection solvent solution 2 containing a sample to be detected is in contact with the electrode element for electrochemical measurement 1 and the solvent is evaporated and dried. It is explanatory sectional drawing which shows the state to do. In addition, the electrode element 1 for electrochemical measurements in FIG. 2 is the AA cross section in FIG.

  In the figure, reference numeral 11 denotes a glass substrate, and an electrochemical measurement electrode portion 12 is formed by sputtering bismuth at a substantially central portion of the glass substrate 11. Reference numeral 13 denotes an electrode pad laminated by sputtering chromium and gold on the end portion of the glass substrate 11. The electrode pad 13 is laminated by sputtering chromium and gold so as to connect the electrode part for electrochemical measurement 12 and the electrode pad 13. The lead wires 14 are connected.

  A water repellent layer 15 is laminated on the glass substrate 11 except for the electrode part 12 for electrochemical measurement and the electrode pad 13. The water repellent layer 15 was a single particle film of polytetrafluoroethylene particles (average particle diameter 1 μm), and the contact angle was 130 degrees.

  The electrochemical measurement electrode element 1 is placed on the hot plate 3, 5 μl of an aqueous solution containing 100 ppb of lead and cadmium is dropped on the electrochemical measurement electrode portion 12 and the water repellent layer 15, and the hot plate 3 is heated to 100 ° C. The aqueous solution was stripped and dried.

  The dried electrode element 1 for electrochemical measurement is immersed in a 0.1 M acetic acid-sodium acetate buffer solution (electrolyte) containing 0.1 M potassium nitrate, and the counter electrode and the reference electrode are immersed, and each electrode is connected to a potentiostat. Immediately, the potential in the range of −1.0 to −0.2 V (vs. Ag / AgCl) is swept by the square wave voltammetry method to elute the heavy metal film on the electrochemical measurement electrode section 12 as ions. The peak current value obtained during elution was recorded.

  Square wave voltammetry is a method in which a rectangular wave is continuously applied to sweep the potential, and a large current response is obtained by taking the difference between the current that flows when the rectangular wave rises and the current that flows when it falls. I can do it. The frequency of the rectangular wave used was 100 Hz, the potential amplitude was 25 mV, and the potential change amount was 2.5 mV. As for the obtained current value, the current value corresponding to lead was 250 μA, and the current value corresponding to cadmium was 140 μA.

(Comparative Example 1)
100 ppb of lead and cadmium are added to 0.1 M acetic acid-sodium acetate buffer containing 0.1 M potassium nitrate, and the electrode used in Example 1 is directly immersed therein, and the counter electrode and the reference electrode are both immersed together Then, a potential of −1.0 V was applied for 60 seconds, and then the potential was swept by the square wave voltammetry method in the same manner as in Example 1 to elute the heavy metal film on the electrochemical measurement electrode section 12 as ions. The peak current value obtained during elution was recorded. The obtained current value was 20 μA corresponding to lead and 15 μA corresponding to cadmium.

(Example 2)
FIG. 3 is a plan view showing a different example of the electrode element 4 for electrochemical measurement, and FIG. 4 shows that the solvent is volatilized in the state where the detection solvent solution 2 containing the sample to be detected is in contact with the electrode element 4 for electrochemical measurement. It is explanatory sectional drawing which shows the state dried then. In addition, the electrode element 4 for electrochemical measurements in FIG. 4 is a BB cross section in FIG.

  In the figure, reference numeral 11 denotes a glass substrate, and a dot-like electrode portion for electrochemical measurement 12 laminated by sputtering bismuth at a substantially central portion of the glass substrate 11 is formed. A circular reference electrode 16 is formed around the electrode portion 12 for electrochemical measurement via a water repellent layer 15. The reference electrode 16 is a silver / silver chloride electrode laminated on the glass substrate 11 by sputtering silver.

  Reference numerals 13 and 13 are electrode pads laminated by sputtering chromium and gold on the end of the glass substrate 11, and chromium and gold are connected so as to connect the electrode part 13 for electrochemical measurement and the reference electrode 16 to the electrode pad 13. Are connected by the lead wires 14 laminated by sputtering.

  The water repellent layer 15 is laminated on the glass substrate 11 except for the electrode pad 13 on the outer periphery of the reference electrode 16. The water repellent layer 15 was a single particle film of polytetrafluoroethylene particles (average particle diameter 1 μm), and the contact angle was 130 degrees.

  An electrode element 4 for electrochemical measurement is placed on the hot plate 3, and 0.1 M acetic acid-sodium acetate containing heavy metal (lead, cadmium) and 10 mM potassium chloride on the electrode part 12, the reference electrode 16 and the water repellent layer 15. 5 μl of a buffer solution was dropped and heated at 100 ° C. for 60 seconds on the hot plate 3 while applying a potential of −1.0 V (vs. Ag / AgCl) to the electrode part 12 with a potentiostat, and the volume of the droplet was reduced. Reduced to 1/10.

  A silver / silver chloride reference electrode and a platinum plate counter electrode were immersed in a beaker filled with a 0.1 M acetic acid-sodium acetate buffer containing 0.1 M potassium nitrate. The reference electrode and the platinum plate counter electrode are connected to a potentiostat and a personal computer, and are connected to the dried electrochemical measurement electrode unit 12 so that −1.0 V (vs. Ag / AgCl) is applied to the electrochemical measurement electrode unit 12. Immediately after immersion, the potential in the range of −1.0 to −0.2 V (vs. Ag / AgCl) was swept using the square wave voltammetry method, and the heavy metal collected on the electrode portion 12 was removed. Elution was performed as ions, and the peak current value obtained at the time of elution was recorded. The frequency of the rectangular wave used was 100 Hz, the potential amplitude was 26 mV, and the potential change amount was 2.5 mV.

  Heavy metal (lead, cadmium) was measured at 50 ppb intervals between 50 and 200 ppb. The anodic stripping voltammograms obtained and the calibration curves in which the respective peak current values are plotted against the heavy metal concentration are shown in FIGS.

(Example 3)
In the electrode element 4 for electrochemical measurement, the electrode element 4 for electrochemical measurement used in Example 2 was used except that a silver / silver iodide electrode was used as the reference electrode 12.

  The electrode element 4 for electrochemical measurement is placed on the hot plate 3, and heavy metal (lead, cadmium), 10 mM nitric acid and 0.1 mM iodine are placed on the electrode part 12 for electrochemical measurement, the reference electrode 16 and the water repellent layer 15. 5 μl of a solution containing silver halide was dropped and heated at 100 ° C. for 60 seconds on the hot plate 3 while applying a potential of −0.8 V (vs. Ag / AgI) to the electrode portion 12 for electrochemical measurement with a potentiostat. The volume of the droplet was reduced to about 1/10.

  A silver / silver chloride reference electrode and a platinum plate counter electrode were immersed in a beaker filled with a solution containing 10 mM nitric acid and 0.1 mM silver iodide. While connecting a reference electrode and a platinum plate counter electrode to a potentiostat and a personal computer, and connecting to the dried electrode part 12 for electrochemical measurements, applying -0.8V (vs. Ag / AgCl) to the electrode part 12 Immediately after the immersion, the potential in the range of −0.8 to −0.2 V (vs. Ag / AgCl) was swept using the square wave voltammetry method, and the heavy metal collected in the electrochemical measurement electrode unit 12 was removed. Elution was performed as ions, and the peak current value obtained at the time of elution was recorded. The frequency of the rectangular wave used was 100 Hz, the potential amplitude was 26 mV, and the potential change amount was 2.5 mV.

  Heavy metal (lead, cadmium) was measured at 50 ppb intervals between 50 and 200 ppb. The obtained anodic stripping voltammograms and calibration curves obtained by plotting the respective peak current values against the heavy metal concentrations are shown in FIGS.

It is a top view which shows an example of the electrode element for electrochemical measurements. It is explanatory sectional drawing which shows the state which volatilizes a solvent and dries in the state which contacted the detection solvent solution containing a to-be-detected sample to the electrode element for electrochemical measurements. It is a top view which shows the example from which the electrode element for electrochemical measurements differs. It is explanatory sectional drawing which shows the state which volatilizes a solvent and dries in the state which contacted the detection solvent solution containing a to-be-detected sample to the electrode element for electrochemical measurements. 3 is an anodic stripping voltammogram obtained in Example 2. FIG. 4 is a calibration curve in which peak current values obtained in Example 2 are plotted against heavy metal concentrations. 4 is an anodic stripping voltammogram obtained in Example 3. FIG. 4 is a calibration curve in which peak current values obtained in Example 3 are plotted against heavy metal concentrations.

DESCRIPTION OF SYMBOLS 1 Electrochemical measurement electrode element 2 Sample solvent solution 3 Hot plate 4 Electrochemical measurement electrode element 5 Optical measurement element 11 Glass substrate 12 Electrochemical measurement electrode part 13 Electrode pad 14 Lead wire 15 Water repellent layer 16 Reference electrode 17 Glass substrate

Claims (18)

  The process of volatilizing and drying the solvent while the detection solvent solution containing the analyte to be detected is in contact with the electrode part for electrochemical measurement of the electrode element for electrochemical measurement, and electrochemical measurement of the dried electrode element for electrochemical measurement A step of immersing the electrode part for liquid in a liquid and a step of quantifying the analyte to be detected by an electrochemical measurement method by applying a voltage higher than the oxidation potential of the analyte to be detected to the electrode part for electrochemical measurement. A microanalysis method. Electrochemical measurement electrode element made of an electrochemical measuring electrode portion and the non-electrode portion, microanalysis method of claim 1, wherein the non-electrode portion, characterized in that it is water repellent. 3. The microanalysis method according to claim 1 or 2, wherein the analyte is quantified by an electrochemical measurement method by immersing the reference electrode in a liquid. 4. The microanalysis method according to claim 3 , wherein the reference electrode is a silver / silver halide electrode. The microanalysis method according to claim 4 , wherein the liquid contains a halogen ion. 5. The microanalysis method according to claim 4 , wherein the silver / silver halide electrode is a silver / silver iodide electrode. The microanalysis method according to claim 6 , wherein the liquid contains iodine ions.   The electrode for electrochemical measurement in a state where the detection solvent solution containing the analyte to be detected is in contact with the reference electrode capable of determining the potential of the electrode portion for electrochemical measurement and the electrode portion for electrochemical measurement of the electrode element for electrochemical measurement The process of volatilizing the solvent and reducing the volume of the detection solvent solution while applying a potential at which the analyte can be precipitated from the detection solvent solution on the head to the electrode for electrochemical measurement A microanalysis method characterized by comprising a step performed by a measurement method. 9. The trace element according to claim 8, wherein the electrochemical measurement electrode element has an electrochemical measurement electrode part and a reference electrode formed through a non-electrode part, and the non-electrode part is subjected to a water repellent treatment. Analysis method. 10. The microanalysis method according to claim 8 , wherein the reference electrode is a silver / silver halide electrode. The microanalysis method according to claim 10 , wherein the detection solvent solution contains a halogen ion. 11. The microanalysis method according to claim 10 , wherein the silver / silver halide electrode is a silver / silver iodide electrode. The microanalysis method according to claim 12 , wherein the detection solvent solution contains iodine ions. The microanalysis method according to claim 2 or 9 , wherein a contact angle with a detection solvent solution containing a sample to be detected in a portion subjected to water repellent treatment is 90 degrees or more. The trace analysis method according to any one of claims 1 to 14 , wherein the solvent is volatilized by a heater installed in the vicinity of the wetted part. The microanalysis method according to any one of claims 1 to 15 , wherein the quantification of the analyte to be detected is an amperometry method, a voltammetry method or a coulometry method. The microanalysis method according to any one of claims 1 to 16 , wherein the analyte to be detected is a heavy metal. 18. The microanalysis method according to claim 17 , wherein the heavy metal is quantified by a stripping voltammetry method.

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