JP4691726B2 - Cadmium ion sensor using mixed LB film - Google Patents

Description

  The present invention relates to a cadmium ion concentration sensor used for analyzing harmful cadmium ions contained in environmental samples and the like. More specifically, the present invention comprises a cadmium ion responsive dye and a polymer compound. The present invention relates to a cadmium ion sensor having a mixed Langmuir-Blodget cumulative film (mixed LB film) as a sensitive site. The present invention provides a simple high-sensitivity cadmium ion sensor that enables on-site measurement that is strongly demanded in the field of water quality management. The present invention adopts a new method that utilizes the change in color tone of the solid sensor material, thereby simplifying the current cadmium drainage standard value (0.1 mg / L) and environmental standard value (0.01 mg / L), It provides new technologies and new products related to a new type of cadmium ion sensor that can realize detection and quantification quickly, with high sensitivity and at low cost.

  Cadmium ions in environmental sample water such as environmental water have a great impact on the ecosystem even in trace amounts. Especially, the health damage to the human body is very serious, for example, the so-called Itai Itai disease that occurred in Toyama Prefecture. It is well known from examples such as. Therefore, grasping the concentration of cadmium ions in the environmental sample water is an extremely important matter for environmental conservation. Conventionally, measurement of the cadmium ion concentration in these environmental sample waters has been performed by instrumental analysis methods such as absorptiometry, atomic absorption spectrophotometry, or inductively coupled plasma emission spectrometry that are complicated and require skill and time for operation. (JIS).

  Therefore, it is difficult to quickly grasp the environmental water contamination by cadmium ions, which is one of the causes of troublesome pollution countermeasures. On the other hand, simple methods for measuring the concentration of various ions in environmental samples have been proposed and some of them have been commercialized. For example, for cadmium ions, such a simple measurement method has been put into practical use. There are almost no examples, and the generally used ion electrode method has a drawback that its detection sensitivity is not sufficient.

  In addition, since the Langmuir-Blodgett film can easily obtain an organic thin film, research on various sensors using the film has been actively conducted. As a prior art, for example, a chemical sensor (Patent Document 1) in which an enzyme, antigen or antibody molecule having activity against a specific chemical substance is immobilized on a transducer, and an optically detectable dye are determined. Photochemical sensor comprising a hydrophilic region and a hydrophobic region including an ionophore for the ion to be produced (Patent Document 2), a membrane potential sensitive dye for measuring a specific component in a sample, and an ultra-thin LB film An optical sensor (Patent Document 3) fixed inside is proposed. However, since these thin films generally have a defect that lacks mechanical stability, it is practically essential to improve their structural stability. For this reason, a technique using a more stable polymer LB film (Patent Document 4) has been proposed, but this technique is limited to the outermost surface of the monomolecular LB film that is farthest from the support being hydrophilic. Furthermore, nothing is shown about a mixed film of a monomolecular compound and a polymer compound.

Japanese Patent Laid-Open No. 62-207951 JP 2000-28532 A JP-A-5-332937 JP 63-166263 A

  Under such circumstances, the present inventor, in view of the above prior art, as a result of earnest research for the purpose of developing a cadmium ion sensor that can easily detect cadmium ions in water with high sensitivity, results in cadmium ions. We have found that a target cadmium ion sensor can be obtained by constructing a mixed LB film composed of a responsive dye and a polymer compound as a sensitive site on a support, and further research has been completed to complete the present invention. It was.

  An object of the present invention is to provide a cadmium ion sensor that can easily detect cadmium ions in water such as environmental water with high sensitivity. Furthermore, the present invention provides a cadmium ion sensor having, as a sensitive site, a mixed Langmuir-Blodgett membrane containing a dye having a property of changing color tone by reacting with cadmium ions in water such as environmental water as a sensitive site. The object is to provide a novel cadmium ion sensor that functions as a cadmium ion sensor by construction.

The present invention for solving the above-described problems comprises the following technical means.
(1) In the cadmium ion sensor, the sensitive part is composed of a cadmium ion responsive dye and a polymer compound , or a single film of each component of the responsive dye and the polymer compound is separately laminated. A cadmium ion sensor having a film-like sensitive site formed by accumulating a mixed LB film on a support in a single layer or multiple layers.
(2) The cadmium ion sensor according to (1), wherein the cadmium ion-responsive dye is a dye having a property of changing color tone by reacting with cadmium ions in water.
(3) The cadmium ion sensor according to (2), wherein the dye is an azo dye, a triphenylmethane dye, a porphyrin dye, a phthalocyanine dye, or a Schiff base dye.
(4) The cadmium ion sensor according to (1) above, wherein the polymer compound includes a condensation polymer compound composed of a polypeptide, polyester, polycarbonate, polyamine, polyamide, polyimide, polyurethane, polyurea, polysulfide, or polysulfone. .
(5) Addition polymerization compound system in which the polymer compound has a hydrophilic group comprising a carboxyl group, a ketone group, an ester group, an ether group, an amino group, an amide group, an imide group, a urea group, a hydroxyl group, or a sulfonic acid group The cadmium ion sensor according to (1), including a molecular compound.
(6) The cadmium ion sensor according to (1), wherein the support is a glass plate, a synthetic resin plate, or a quartz plate.
(7) The cadmium ion sensor according to (1), wherein each component is mixed in the same film in a mixed LB film composed of a cadmium ion responsive dye and a polymer compound.
( 8 ) The cadmium ion sensor according to (1), wherein the membrane farthest from the support is an LB membrane containing a polymer compound.
( 9 ) The cadmium ion sensor according to ( 8 ), wherein the LB film containing the polymer compound is accumulated in multiple layers.

Next, the present invention will be described in more detail.
The cadmium ion sensor according to the present invention has a film-like sensitive site formed by accumulating a mixed LB film composed of a cadmium ion-responsive dye and a polymer compound in a single layer or multiple layers on a support as a sensitive part. It is a feature. In the mixed LB film composed of the cadmium ion responsive dye and the polymer compound, the present invention is such that the respective components are mixed in the same film, and the cadmium ion responsive dye and the polymer compound. In the mixed LB film, the individual films of the respective components are separately laminated and constructed.

  In order to solve the above-mentioned problems, the present inventor has made extensive studies on the development of cadmium ion sensor materials, and as a result, is a known technique for a dye that reacts with cadmium ions in water such as environmental water to change its color tone. It has been found that a cadmium ion sensor having a property of changing the color tone in response to cadmium ions in water and having high structural stability can be created by forming a thin film on a support by the Langmuir-Blodgett method.

  The dye that reacts with cadmium ions in water and changes its color tone used in the present invention has a property of changing its color tone in response to a specific cadmium ion, and can form an LB film. For example, any dye can be used, but a dye that is hardly soluble in water is preferably used. For example, an azo dye represented by Chemical Formula 1 can be used. Other examples include triphenylmethane dyes, porphyrin dyes, phthalocyanine dyes, Schiff base dyes, and the like. Thus, in the present invention, any dye can be used as long as it is a dye that reacts with cadmium ions to change its color tone and forms an LB film by the manufacturing method according to the present invention.

  In the present invention, the dye molecules are formed on the support alone or mixed with a polymer compound. In any case, a dye molecule or a mixture of a dye molecule and a polymer compound is dissolved in a volatile solvent, and this is spread on a water surface to form a film, which is transferred to a support in a single layer or multiple layers. By taking it, it forms into a monomolecular film or a multilayer film. As a method for transferring the film to the support, a vertical dipping method and a horizontal adhesion method can be used. However, in the present invention, the method for transferring the film is not limited, and any method can be used.

  Further, the mixing ratio of the dye and the polymer compound is not particularly limited, and is appropriately determined from the amount of the dye within a range in which a change in color tone caused by reaction with cadmium ions in water can be read. Further, in order to stabilize the film and reduce the loss of the dye, it is preferable to form a film of the polymer compound not containing the dye on the outermost film of the film containing the dye. In this case, in the present invention, it does not matter whether the outermost film of the film containing the dye is hydrophilic or hydrophobic. Further, the number of polymer compound LB films laminated on the outermost film is not particularly limited, and can be arbitrarily determined in consideration of the stability of the film.

  In the present invention, the support for accumulating the LB film may be any support as long as it can transfer the accumulated film from the water surface. For example, a glass plate, a synthetic resin plate, a quartz plate, etc. are preferable. Used. Preferable examples of the synthetic resin plate include an acrylic plate, a polyvinyl chloride plate, a polyethylene plate, a polypropylene plate, and a Teflon (registered trademark) plate. However, it is not limited to these. These are used in a shape of, for example, 10 mm × 50 mm and a thickness of 1 mm, but the material and form are not particularly limited, and the material and form are arbitrarily selected according to actual use. can do.

  The polymer compound used in the present invention has a molecular weight of 1000 or more, preferably 10,000 or more. Any polymer compound can be used as long as it can be formed as a Langmuir-Blodgett film. In the present invention, examples of desirable polymer compounds include the following.

  That is, in the present invention, the polymer compound is preferably a condensed polymer compound such as a polypeptide, polyester, polyamide, polyurethane, polyurea, polyamine, polysulfide, polysulfone, polycarbonate, polyimide, and ester group. Amide group, ketone group, carboxyl group, imide group, urea group. An addition polymerization compound polymer compound having a hydrophilic group such as a carbonic acid ester group, an amino group, a hydroxyl group or an ether group, or a compound having the same or similar properties as these is used.

  In the present invention, a cadmium ion sensor produced using the dye represented by Chemical Formula 1 and a glass plate as a support exhibits a visible ultraviolet absorption spectrum as shown in FIG. 1 and exhibits an orange color. This reacts with cadmium ions in water and turns purple according to its concentration. Therefore, its absorption spectrum also changes as shown in FIG. In the present invention, the cadmium ion concentration is measured by using a method for visually determining a change in the color tone of the support and a method for measuring absorbance at a wavelength of 600 nm using a device such as a visible ultraviolet absorptiometer. can do.

  Conventionally, instrumental analysis methods such as absorptiometry, atomic absorptiometry, inductively coupled plasma emission spectrometry, etc. have been employed in methods and apparatuses for measuring cadmium ion concentration, but these methods and apparatuses are cumbersome and difficult to operate. Since it requires skill and time, there is a problem that the range of its use is greatly limited. On the other hand, in the present invention, by adopting a new method using a change in color tone of a solid sensor material using a mixed LB film composed of a cadmium ion responsive dye and a polymer compound as a sensitive site, It is possible to construct and provide a new type of cadmium ion sensor capable of on-site measurement capable of detecting and quantifying cadmium drainage standard values and environmental standard values easily, quickly, with high sensitivity and at low cost.

The present invention has the following effects.
(1) According to the present invention, it is possible to provide a cadmium ion sensor capable of detecting and quantifying cadmium ions in water with simple operation, high sensitivity, and low cost.
(2) According to the present invention, for example, 10 ⁻⁷ M (M = mol / l) using a cadmium ion sensor produced using the dye represented by Chemical Formula 1 and a glass plate as a support. ) Can be detected within 15 minutes without the need for skilled operation.
(3) When cadmium ions of the same concentration are to be measured by the conventional technique, an operation by a skilled analyst is usually required for one hour or more by using a large apparatus. The sex can be greatly improved.
(4) In the present invention, since a dye having a selected specific property is converted into a sensor based on the above-described configuration of the present invention, a special effect as a cadmium ion sensor that cannot be obtained only by the dye can be obtained.
(5) In the present invention, a cadmium ion sensor having the same effect can be constructed by selecting a specific dye that responds to cadmium ions and applying the technique of the present invention.
(6) In the present invention, a cadmium ion sensor having the same effect can be constructed by selecting a support capable of accumulating a dye as an LB film and applying the technique of the present invention.

  Next, the present invention will be specifically described with reference to production examples and examples, but the following production examples and examples do not limit or limit the scope of the present invention.

Production Example 1
First, the dye represented by the chemical formula 1 preferably used in the present invention is dissolved in benzene (10 ⁻³ mol dm ⁻³ ), and 200 μL of the dye is spread on the water surface in the water tank. It was compressed by an appropriate method to form a dye film on the water surface. Subsequently, the glass plate previously installed in the water tank was pulled up vertically at an appropriate speed, and the dye film on the water surface was transferred onto the glass plate. The glass plate was again pushed back into the water tank again to laminate the next dye film.

In this way, when the predetermined number of layers is reached, the dye on the water surface is sucked off and removed, and 200 μL of a polymer benzene solution (10 ⁻³ mol dm ⁻³ ) preferably used in the present invention is removed from the water surface. Expanded above. After the development, the surface was compressed again, and when a polymer LB film was produced on the water surface, the polymer LB film was formed on the outermost surface by moving up and down the glass plate on which the aforementioned dye was laminated.

Production Example 2
Moreover, after preparing the mixed benzene solution (10 ^<-3 > moldm <^-3> ) of the pigment | dye represented by said Chemical Formula 1 and a polymer LB film | membrane beforehand and spreading | deploying 200 microliters on the water surface in a water tank, the surface of an aqueous phase Was compressed by an appropriate method to form a dye-polymer mixed LB film on the water surface. Subsequently, the glass plate previously installed in the water tank was pulled up vertically at an appropriate speed, and the dye-polymer mixed LB film on the water surface was transferred onto the glass plate. This glass plate was pushed back into the water tank again vertically, and the next dye-polymer mixed LB film was laminated.

In this way, when the predetermined number of layers is reached, the dye on the water surface is removed by sucking or the like, and 200 μL of a polymer benzene solution (10 ⁻³ mol dm ⁻³ ) preferably used in the present invention is removed. Developed on the surface of the water. After the development, the surface is compressed again, and when the polymer LB film is produced on the water surface, the polymer LB film is formed on the outermost surface by moving up and down the glass plate on which the aforementioned dye-polymer mixed LB film is laminated. I let you.

Take 20 mL of a 1 × 10 ⁻⁴ mol dm ⁻³ cadmium ion aqueous solution with a pH of 7.5 in a 50 mL sample bottle with a lid, and put the cadmium ion sensor prepared in Production Example 1 or Production Example 2 into this. And left in a warm bath at 40 ° C. The sensor was taken out from the sample bottle by changing the standing time, and its absorption spectrum was measured. The results are shown in FIGS. From this, it was found that the change in the absorption spectrum of the sensor in response to the cadmium ions was almost constant over 15 minutes.

20 mL of 1 × 10 ⁻⁴ mol dm ⁻³ cadmium ion aqueous solutions each having a different pH are placed in a 50 mL sample bottle with a lid, and the cadmium ion sensor prepared in Production Example 1 or 2 is placed therein, and the temperature is 40 ° C. in a warm bath. Left for 15 minutes. Next, the sensor was taken out from the sample bottle, and its absorbance was measured. The result is shown in FIG. From this, it was found that the most optimum pH was approximately 7.5.

10 mL of the sample aqueous solution was placed in a 50 mL sample bottle with a lid, and 10 mL of pH 7.5 buffer was added thereto to make a total volume of 20 mL. The cadmium ion sensor produced in Production Example 1 or Production Example 2 was put in this, and left in a warm bath at 40 ° C. for 15 minutes. Subsequently, the sensor was taken out from the sample bottle, and the presence or absence of the color change was visually determined to determine the presence of cadmium. The analyte concentration that can be determined by this operation was at least 1 × 10 ⁻⁷ M (about 6 ppb).

  Similarly, 10 mL of a standard sample solution containing a known amount of cadmium ion was placed in a 50 mL lidded sample bottle, and 10 mL of pH 7.5 buffer was added to make a total volume of 20 mL. The cadmium ion sensor produced in Production Example 1 or Production Example 2 was put in this, and left in a warm bath at 40 ° C. for 15 minutes. Subsequently, the sensor was taken out from the sample bottle, and the absorbance at 600 nm was measured. FIG. 4 shows the relationship (calibration curve) between the absorbance after the background correction and the cadmium ion concentration.

  As described above in detail, the present invention relates to a cadmium ion sensor using a mixed LB film. According to the present invention, a mechanically stable and highly sensitive cadmium ion sensor can be produced and provided. It becomes possible. According to the present invention, it is possible to provide a new cadmium ion detection and quantification method using the color tone change of a solid sensor material. According to the present invention, it is possible to provide a cadmium ion sensor capable of detecting, quantifying current cadmium emission standard values and environmental standard values simply, quickly and at low cost. By using the cadmium ion sensor of the present invention, instead of the measurement by the conventional method, which requires a great amount of labor and cost by an expensive apparatus, a simple instrument set is used at the measurement site, and the drainage standard value (0.1 mg / L) or environmental standard value (0.01 mg / L) cadmium ions can be detected.

The influence of reaction time on the absorption spectrum change by the cadmium ion of the cadmium ion sensor manufactured by this invention is shown. The influence of reaction time on the absorbance change by cadmium ion of the cadmium ion sensor manufactured by this invention is shown. The influence of pH on the cadmium ion response of the cadmium ion sensor manufactured by this invention is shown. The cadmium ion calibration curve of the cadmium ion sensor manufactured by this invention is shown.

Claims (9)

In the cadmium ion sensor, as a sensitive part, a mixed LB composed of a cadmium ion responsive dye and a polymer compound , or a single layer of each component of the responsive dye and the polymer compound is separately laminated. A cadmium ion sensor characterized by having a membrane-like sensitive site formed by accumulating a membrane on a support in a single layer or multiple layers.   The cadmium ion sensor according to claim 1, wherein the cadmium ion responsive dye is a dye having a property of changing color tone by reacting with cadmium ions in water.   The cadmium ion sensor according to claim 2, wherein the dye is an azo dye, a triphenylmethane dye, a porphyrin dye, a phthalocyanine dye, or a Schiff base dye.   The cadmium ion sensor according to claim 1, wherein the polymer compound includes a condensation polymer compound composed of a polypeptide, polyester, polycarbonate, polyamine, polyamide, polyimide, polyurethane, polyurea, polysulfide, or polysulfone.   An addition polymerization compound-based polymer compound in which the polymer compound has a hydrophilic group comprising a carboxyl group, a ketone group, an ester group, an ether group, an amino group, an amide group, an imide group, a urea group, a hydroxyl group, or a sulfonic acid group The cadmium ion sensor according to claim 1, comprising:   The cadmium ion sensor according to claim 1, wherein the support is a glass plate, a synthetic resin plate, or a quartz plate.   The cadmium ion sensor according to claim 1, wherein each component is mixed in the same film in a mixed LB film composed of a cadmium ion responsive dye and a polymer compound.   The cadmium ion sensor according to claim 1, wherein the film farthest from the support is an LB film containing a polymer compound. The cadmium ion sensor according to claim 8 , wherein the LB film containing the polymer compound is accumulated in multiple layers.

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