KR20110084035A - Electrochemical sensor with conducting polymer modified electrodes for a simultaneous detection of phenolic isomers and manufacturing method the same - Google Patents

Abstract

PURPOSE: An electrochemical sensor using a conductive polymer electrode and manufacturing method thereof are intended to simultaneously detect phenolic isomers using a sensor. CONSTITUTION: An electrochemical sensor can simultaneously detect phenolic isomers. The phenolic isomers are hydroquinone and catechol.

Description

Electrochemical sensor with conducting polymer modified electrodes for a simultaneous detection of phenolic isomers and manufacturing method the same}

The present invention relates to an electrochemical sensor using a conductive polymer electrode capable of simultaneous detection of phenolic isomers and a method of manufacturing the same, and more particularly to hydroquinone (HQ) and catechol (CT), which are phenolic isomers. The present invention relates to an electrochemical sensor capable of simultaneously detecting and a method of manufacturing the same, and a method of simultaneously detecting hydroquinone and catechol using the sensor.

Isomers of phenolic compounds (hydroquinone) and catechol (catechol) are used in a variety of cosmetics, insecticides, fragrances, pharmaceuticals, and photography chemicals.

However, it is designated as one of the major environmental pollutants by the US Environmental Protection Agency (EPS) and the European Union (EU) as a substance that causes environmental pollution when exposed to the natural environment. In particular, it is one of the main substances in tobacco smoke, which is very harmful to humans and animals even at very low concentrations.

High levels of hydroquinone not only cause fatigue and headache, but also damage the kidneys. In addition, catechol is usually present with hydroquinone in nature, but also causes renal tube degeneration and hepatic deterioration. Since the two substances coexist in nature, they have high selectivity for separate detection of each substance. Highly sensitive methods of analysis are required.

In general, for the detection of hydroquinone and catechol, technically, liquid chromatography ( Chromatographia 1999 , 49, 208-211), spectroscopic methods ( J. Pharm. Biomed, Anal. 2001 , 25, 417-424), and Electroluminescence ( Talanta 2000 , 53, 661-666) has been reported, but in most cases it requires pretreatment for detection and separate purification of samples ( J. Chromatogr. A 1999 , 855, 171-179). .

On the other hand, methods of using chemically surface-modulated electrodes for the separate and simultaneous detection of isomers are well known and have many advantages. Glassy electrodes surface-modulated with multi-carbon nanotubes with carboxylic acid functional groups can separate oxidation peaks of hydroquinone and catechol ( Electroanalysis 2005 , 17, 832-838), and polyglutamic acid (Poly ( The glassy carbon electrode surface-modulated with glutamic acid) can be used to simultaneously detect hydroquinone and catechol ( Int. J. Electrochem. Sci. 2007 , 2, 123-132). In addition, simultaneous detection of phenolic isomers using carbon fiber electrodes surface-modulated with titanium oxide is known, but the preparation and application of these methods are complicated, time-consuming, and require a large amount of samples. There was a problem with.

In addition, the simultaneous detection of two samples also had the disadvantage that the background current (background current) is very large.

Therefore, the inventors of the present invention have made an effort to develop an electrochemical sensor which is very simple in fabricating an electrode, minimizes the amount of sample used, and enables simultaneous detection of phenolic isomers having excellent stability. The present invention was completed by fabricating an electrode and confirming that the phenolic isomer can be detected simultaneously using the electrode.

After all, the present invention has been made to solve the above disadvantages, the main object of the present invention is to provide an electrochemical sensor capable of the simultaneous detection of phenolic isomers (phenolic isomers) and a method of manufacturing the same.

Another object of the present invention is to provide a method for simultaneously detecting phenolic isomers using the sensor.

In order to achieve the above object, the present invention provides an electrochemical sensor capable of the simultaneous detection of phenolic isomers (phenolic isomers).

In the present invention, the phenol isomer is characterized in that the hydroquinone and catechol (catechol), the sensor is a glassy carbon (glass carbon) electrode, gold (Pt) electrode, platinum (Pt) electrode or carbon ( carbon) is characterized in that it comprises a conductive polymer coupled to the surface of the electrode selected from among the electrodes by an electrochemical polymerization. In addition, the conductive polymer is characterized in that the thioneine (thionine, C ₁₄ H ₁₃ N ₃ O ₂ S) as a monomer.

The present invention also relates to a phenolic isomer using a conductive polymer electrode prepared by a method of forming a thin film on the surface of an electrode by polymerizing a conductive polymer by cyclically changing a potential using a monomer of thionine as a monomer. It provides a method of manufacturing an electrochemical sensor for the simultaneous detection of.

In the present invention, the electrode is selected from glass carbon, gold (Au), platinum (Pt) or carbon (carbon), and polished with alumina slurry to wash with distilled water in order to increase the contact efficiency with the conductive polymer. The conductive polymer electrode is subjected to a pretreatment process of applying an isopotential of 1.8 V for 400 seconds in a phosphate buffer of pH 6.5 containing a thionine electrode voltage -0.4 to 0.1. It is characterized in that a thin film is formed by electrochemical polymerization of conductive thionine polymer on the surface of the electrode by cyclically changing the potential in the V section.

The present invention also provides a method for simultaneously detecting phenolic isomers using the electrochemical sensor prepared as described above.

The electrochemical sensor according to the present invention can not only detect phenolic isomers which are environmental pollutants at the same time, but also make the electrode fabrication process very simple, minimize the amount of samples used, and mix the two The electrochemical signal for the sample is very well separated and its sensitivity is also very good and can be usefully utilized.

Figure 1 shows the deposition of the electrode of the conductive polymer tyonine by the electrochemical polymerization method of the present invention.
FIG. 2A shows a cyclic voltammogram of 0.5 mM hydroquinone in 0.1M phosphate buffer (PBS, pH = 7.0) of a conductive polymer electrode (Polythionine modified GCE; b) and an organic carbon electrode (Bare GCE) a of the present invention. Voltammograms, CVs) (Scan rate: 30 μs / sec).
2b is a cyclic voltammogram of 0.5 mM catechol in 0.1 M phosphate buffer (PBS, pH = 7.0) of a conductive polymer electrode (Polythionine modified GCE; b) and an organic carbon electrode (Bare GCE) of the present invention. Voltammograms, CVs) (Scan rate: 30 μs / sec).
Figure 3a is a differential pulse voltammetry curve of 0.5 mM hydroquinone in 0.1 M phosphate buffer (PBS, pH = 7.0) of the conductive polymer electrode (Polythionine modified GCE; b) and the organic carbon electrode (Bare GCE; a) of the present invention (Differential Pulse Voltammograms, DPVs) (Pulse amplitude: 50 Hz; pulse width: 2 Hz).
Figure 3b is a differential pulse voltammetry curve of 0.5 mM catechol in 0.1 M phosphate buffer (PBS, pH = 7.0) of the conductive polymer electrode (Polythionine modified GCE; b) and the organic carbon electrode (Bare GCE) of the present invention (Differential Pulse Voltammogram, DPVs) (Pulse amplitude: 50 Hz; pulse width: 2 Hz).
FIG. 4A shows 0.5 mM hydroquinone (HQ) and 0.5 mM catechol in 0.1 M phosphate buffer (PBS, pH = 7.0) of the conductive polymer electrode (Polythionine modified GCE; b) and the organic carbon electrode (Bare GCE; a) of the present invention. Cyclic Voltammograms (CVs) of the chol mixed solution are shown.
4B shows 0.5 mM hydroquinone (HQ) and 0.5 mM catechol in 0.1 M phosphate buffer (PBS, pH = 7.0) of the conductive polymer electrode (Polythionine modified GCE; b) and the organic carbon electrode (Bare GCE; a) of the present invention. Differential Pulse Voltammogram (DPVs) of the chol mixed solution is shown.
FIG. 5A shows a plot of peak potential as a function of cyclic voltammograms (CVs) and pH of 0.5 mM hydroquinone at pH of various phosphate buffers of the conductive polymer electrode of the present invention.
5b shows a plot of peak potential as a function of pH and cyclic voltammograms (CVs) of 0.5 mM catechol at the pH of various phosphate buffers of the conductive polymer electrode of the present invention.
6a is a mixed solution of 0.5 mM hydroquinone and 0.5 mM catechol in 0.1 M phosphate buffer (PBS, pH = 7.0) of the conductive polymer electrode (Polythionine modified GCE; b) and the organic carbon electrode (Bare GCE; a) of the present invention. Cyclic voltage current curves (Cyclic Voltammograms, CVs) for each scan rate of (scan rate: a → i: 10, 20, 30, 50, 75, 100, 150, 200 and 300 mA / sec) .
Figure 6b shows a plot of the peak current (versus) scan rate square root of the hydroquinone and catechol mixture solution.
Figure 7a is a concentration of a variety of catechol including a 200 μM hydroquinone of the conductive polymer electrode of the present invention (a → i: 5, 10, 20, 30, 40, 50, 60, 70, 90, 120, 150 and 200 μM) Cyclic Voltammograms (CVs) of the mixed solution, and the interpolated figure is a plot of hydroquinone and catechol in DPV peak current density versus versus phosphate buffer (PBS, pH = 7.0). .
Figure 7b is a concentration of a variety of hydroquinone including a 100 μM catechol of the conductive polymer electrode of the present invention (a → i: 5, 10, 20, 30, 40, 50, 60, 70, 90, 120, 150 and 200 μM) Cyclic Voltammograms (CVs) of the mixed solution, and the interpolated figure is a plot of hydroquinone and catechol in DPV peak current density versus versus phosphate buffer (PBS, pH = 7.0). .
8 shows the stability in 0.5 mM hydroquinone (HQ) and 0.5 mM catechol (CT) mixed solution in 0.1 M phosphate buffer (PBS, pH = 7.0) of the conductive polymer electrode of the present invention.

Hereinafter, the present invention will be described in detail.

The present invention provides an electrochemical sensor capable of simultaneous detection of phenolic isomers.

In the present invention, the phenolic isomer is preferably hydroquinone and catechol.

In addition, the sensor includes a conductive polymer coupled to the surface of the electrode selected from among glass carbon electrode, gold (Pt) electrode, platinum (Pt) electrode or carbon electrode through an electrochemical polymerization reaction. preferably consisting of, the conductive polymer is good to tie methionine _{(thionine, C 14 H 13 N} 3 O 2 S) as a monomer.

The present invention is also a phenol isomer using a conductive polymer electrode prepared by a method of forming a thin film on the surface of the electrode by polymerizing a conductive polymer by cyclically changing a potential using a thionine as a monomer. It provides a method for manufacturing an electrochemical sensor for the simultaneous detection of.

In the present invention, the electrode may be selected from glass carbon, gold (Au), platinum (Pt) or carbon (carbon), preferably using a glassy carbon electrode (GCE) In order to improve the contact efficiency with the conductive polymer, it is preferable to further include a surface treatment process of polishing with alumina slurry and washing with distilled water.

In the conductive polymer electrode of the present invention, the surface-treated electrode surface dissolves the thionine monomer in an electrolyte solution, and then, such as current cycling, potential step, or galvanostatic method. The thin film is formed using an electrochemical polymerization method.

Specifically, the conductive polymer electrode is dissolved in the thioine monomer in a phosphate buffer solution of pH 6.0 ~ 7.0 as an electrolyte solution and then applied a constant potential of 1.5 ~ 2.0 V for 300 ~ 500 seconds It is preferable to repeat the electrochemical polymerization at a constant electrode voltage section at 100 mA / sec, and more preferably, a pretreatment process of applying an isopotential of 1.8 V for 400 seconds in a phosphate buffer of pH 6.5 containing a thionine It is good to form a thin film by electrochemically polymerizing a conductive polymer on the surface of the electrode by repeatedly changing the potential in the electrode voltage -0.4 ~ 0.1 V section. At this time, the thickness of the thin film is not limited by this because it can be controlled by the repeated number of times of the electrochemical polymerization method, the electrode voltage section may be changed according to the experimental conditions in consideration of the overall sensitivity of the sensor.

The present invention also provides a method for simultaneously detecting phenolic isomers using the electrochemical sensor.

In the present invention, the phenol isomer is preferably hydroquinone and catechol, but is not limited thereto, and may be used to simultaneously detect other phenol derivatives and their isomers.

Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood by those skilled in the art that these examples are for illustrative purposes only and that the scope of the present invention is not construed as being limited by these examples.

Example 1 Preparation of Conductive Polymer Electrode

In order to prepare a conductive polymer electrode formed with a thin film of a thionin polymer, first, a glassy carbon electrode (GCE) was used with a 0.05 μm alumina slurry (Buekler company) until it had a mirror-like smooth surface with a polishing cloth. After polishing, the mixture was washed with a large amount of secondary distilled water.

The cleaned glassy carbon electrode was pretreated by applying an isopotential of 1.8 V for 400 seconds in 0.1 M phosphate buffer (pH 6.5) containing 1 mM of thionine, and then subjecting the pretreated glassy carbon electrode to 100 mA / sec. A conductive polymer electrode in which a thionine polymer thin film was formed on a glassy carbon electrode was prepared by instantaneously changing a potential 10 times in a -0.4 to 1.0 V section.

Experimental Example 1. Detection of hydroquinone or catechol using conductive polymer electrode

Cyclic voltammetry (CV) and differential pulses of hydroquinone (HQ) and catechol (CT), respectively, using the conductive polymer electrode prepared in Example 1 in 0.1 M phosphate buffer (PBS; pH 7.0) Differential Pulse Voltammetry (DPV) was performed.

In this case, all electrochemical experiments were performed using a CHI 430A electrochemical workstation (CH Instruments, Inc., USA) connected to a PC, and a 3 mm diameter glassy carbon electrode (bare GCE) or the conductive polymer electrode (polythionine modified). GCE) is used as a working electrode, the counter electrode is a platinum wire and the reference electrode is an Ag / AgCl (3M KCl) electrode. It was.

As a result, the cathode and anode peaks of the HQ and CT in the glassy carbon electrode exhibit irreversible electrochemical behavior, whereas the oxidation peak currents of the HQ and CT are reduced in the conductive polymer electrode of the present invention. The cathode peak potentials of HQ and CT shifted negatively, and the cathode peak potentials of HQ and CT shifted positively.

In addition, in the conductive polymer electrode of the present invention, the peak potential separation of HQ and CT was 60 Hz, which was significantly lower than the overpotential of HQ and CT, and the electrochemical reproducibility and enzyme of HQ and CT Activity was also much improved in the conductive polymer electrode of the present invention (see FIGS. 2A and 2B).

On the other hand, the differential pulse voltammograms (DPVs) of 0.5 mM HQ and CT in 0.1 M PBS (pH 7.0) of the glassy carbon electrode and the conductive polymer electrode of the present invention were the same as the cyclic voltammograms (CVs). In the conductive polymer electrode of the present invention, both the peak potential of the HQ and the CT increased and the peak current decreased significantly (see FIGS. 3A and 3B).

Experimental Example 2 Detection of Hydroquinone and Catechol Using Conductive Polymer Electrode (1)

Cyclic voltammetry (CV) and differential pulses in a mixed solution in which hydroquinone (HQ) and catechol (CT) were mixed at the same concentration (0.5 mM each) using the conductive polymer electrode prepared in Example 1 Voltammetry (DPV) was performed in the same manner as in Experiment 1.

As a result, it was confirmed that in the organic carbon electrode (bare GCE), the oxidation peaks of HQ and CT merged into large peaks of CVs and DPVs.

On the other hand, in the conductive polymer electrode of the present invention, two clear peaks of HQ and CT were identified. At the same time, the peak current also increased significantly (see FIGS. 4A and 4B). This means that the current enhancement of CT is greater than HQ when HQ and CT are mixed at the same concentration. For the oxidation of HQ and CT, electron transitions to p-benzoquinone and o-benzoquinone, respectively ( This is because electron transfer is much easier and faster in CT.

The reaction of HQ and CT in the titionine polymer film at pH 4-8 range is pH dependent, and the cathode peak current is constant for both HQ and CT in almost all ranges (see FIGS. 5A and 5B). For convenience, pH 7.0 corresponding to physiological body fluid concentration was selected as the pH for simultaneous detection.

On the other hand, the effect of the scan rate on the oxidation peak current of HQ and CT has already been studied. As the scan rate increases, the oxidation peak current I _pa increases and the oxidation peak current is directly proportional to the square root of the scan rate in the range of 10 to 300 mA / sec, where the regression coefficients are both HQ and CT. 0.99 (see FIGS. 6A and 6B). This result implies that the electrode reaction is a diffusion controlled reaction.

Experimental Example 3. Detection of Hydroquinone and Catechol Using Conductive Polymer Electrode (2)

Differential pulse voltammetry (DPV) in a mixed solution in which hydroquinone (HQ) and catechol (CT) were mixed at different concentrations using the conductive polymer electrode prepared in Example 1 was performed in the same manner as in Experiment 1. Was performed.

At this time, in order to check the selectivity of the conductive polymer electrode of the present invention in the mixed solution of HQ and CT, the concentration of CT is made constant (100 μM), while the concentration of HQ is changed, and vice versa, DPV was performed at constant (200 μM) and varying CT concentrations.

As the concentration of HQ increases, the oxidation peak current of the corresponding HQ increases and the oxidation peak current of the CT remains almost constant. Similarly, as the concentration of CT increases, the oxidation peak of the CT also increases, whereas The oxidation peak remained constant (see FIGS. 7A and 7B).

From the above results, it was found that the oxidation of HQ and CT occurs independently in the conductive polymer electrode of the present invention.

In addition, the calibration plot of HQ and CT can be confirmed depending on the DPV peak current at the concentration of HQ and CT. The HQ and CT oxidation peak currents increased linearly at concentrations ranging from 0.005 to 0.2 mM and the correlation factor of both isomers was 0.98.

Therefore, simultaneous detection of HQ and CT is possible by using the correction plot for HQ in the presence of CT and the correction plot for CT in the presence of HQ in the conductive polymer electrode of the present invention.

Experimental Example 4. Confirmation of stability of conductive polymer electrode

In order to determine the stability of the conductive polymer electrode prepared in Example 1, an interference substance was added to a mixed solution in which hydroquinone (HQ) and catechol (CT) were mixed at the same concentration (each 0.5 mM). Afterwards, HQ, CT and signal levels of each disturbance were measured every 5 minutes and 10 times through cyclic voltage current curves (CVs).

Retarders for simultaneous detection of HQ and CT of the conductive polymer electrode of the present invention under optimized conditions include resorcinol, phenol and nitrophenol.

The individual oxidation peaks of the resorcinol, phenol and nitrophenols have been observed to have little or no disturbance regardless of the concentration, with potentials of values significantly different from those of the HQ and CT or generally with low peak currents ( 8).

When the interferences are mixed in the mixed solution of HQ and CT, the oxidation peak potential and peak current of HQ and CT are almost the same. Moreover, even if NH ₄ ⁺ , Ca ²⁺ , Mg ²⁺ , Fe ³⁺ , Zn ²⁺ , NO ₄ ⁻ , SO ₃ ^2- and citrates are contained in concentrations of 100 times or more, they are not disturbed. It was confirmed (not shown).

From the above results, it was confirmed that the conductive polymer electrode of the present invention has excellent stability.

As described above, specific portions of the contents of the present invention have been described in detail, and for those skilled in the art, these specific techniques are merely preferred embodiments, and the scope of the present invention is not limited thereto. Will be obvious. Thus, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

Claims (10)

Electrochemical sensor capable of simultaneous detection of phenolic isomers. The method of claim 1,
The phenolic isomer is a hydroquinone and catechol (catechol) is characterized in that the electrochemical sensor capable of the simultaneous detection of the phenolic isomer. The method of claim 1,
The sensor comprises a conductive polymer coupled to the surface of the electrode selected from among glass carbon electrode, gold (Pt) electrode, platinum (Pt) electrode or carbon electrode through an electrochemical polymerization reaction. Electrochemical sensor capable of simultaneous detection of phenolic isomers, characterized in that. The method of claim 3, wherein
The conductive polymer is the electrochemical sensor capable of the simultaneous detection of phenolic isomers, characterized in that the monomer (thionine, C ₁₄ H ₁₃ N ₃ O ₂ S) as a monomer. Simultaneous detection of phenolic isomers using a conductive polymer electrode prepared by a method of cyclically changing a potential using a thionine as a monomer to polymerize the conductive polymer and forming a thin film on the electrode surface Method of manufacturing an electrochemical sensor for. 6. The method of claim 5,
The electrode is selected from glass carbon, gold, platinum or carbon, and the surface treatment process is performed by polishing with alumina slurry and washing with distilled water to increase the contact efficiency with the conductive polymer. Method of manufacturing an electrochemical sensor for the simultaneous detection of phenolic isomers further comprising a. 6. The method of claim 5,
The conductive polymer electrode is subjected to a pretreatment process of applying an isoelectric potential of 1.8 V for 400 seconds in a phosphate buffer of pH 6.5 containing tyonine, and then repeatedly changes the electrode voltage in a range of -0.4 to 0.1 V to cause an electrode potential change. A method of manufacturing an electrochemical sensor for the simultaneous detection of phenolic isomers, characterized in that to form a thin film by electrochemical polymerization of conductive thionine polymer on the surface. A method for simultaneously detecting phenolic isomers using the electrochemical sensor. The method of claim 8.
The phenol isomer is a method for simultaneously detecting the phenol isomers using an electrochemical sensor characterized in that hydroquinone and catechol (catechol). The method of claim 8,
The sensor is a method for the simultaneous detection of phenolic isomers, characterized in that produced by the method of any one of claims 5-7.

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