JP4415955B2 - Concentration measuring method and concentration measuring kit for isothiazolones - Google Patents

Description

  The present invention relates to a method for easily and rapidly measuring the concentration of isothiazolones and a kit for measuring the concentration of isothiazolones.

Isothiazolones have a biological function-stopping action and / or biocidal action against many organisms such as molds, bacteria, algae, slime molds, barnacles, and downy mildews, including those causing disease of animals and plants. As a bactericide and biocide, it is widely used in industrial fields such as paints, adhesives, cosmetics, pharmaceuticals, paper pulp, industrial water, cooling water, and metalworking oil.
U.S. Pat. No. 3,761,488

  In these application fields, it is necessary to appropriately control the concentration of isothiazolones contained in the system in order to sufficiently exert the functions of isothiazolones. However, in most applications, the concentration of isothiazolones in the system is quite low, so there is no simple detection method, and concentration measurement is performed by a complicated method using high performance liquid chromatography (HPLC). It was. For this reason, it takes a lot of time and cost to measure the concentration, which hinders proper concentration management.

As one method for solving these problems, a method for detecting isothiazolones relatively easily using an immunoassay has been proposed. However, since this method requires a complicated operation to collect the antibody required for the measurement, it has the disadvantage that the cost required for the concentration measurement increases. In addition, since the antibody lacks stability and has a short life and requires refrigerated storage, there is a problem that it is not suitable for on-site measurement where isothiazolones are actually used. In addition, there is a problem that measurement error is large due to being easily affected by impurities.
JP 7-294522 A

As another method, a method is proposed in which an absorption or emission spectrum is measured in a wide wavelength region of 200 nm to 2500 nm, and a concentration is calculated by applying a chemical measurement algorithm to the spectrum. However, this method has a problem that it is easily affected by a change in concentration of substances other than isothiazolones contained in the sample solution. In addition, there is a drawback that a complicated device is required.
JP-A-6-317522

  An object of the present invention is to provide a concentration measurement method and a concentration measurement kit for isothiazolones which have solved the drawbacks of the prior art. That is, it is to provide a concentration measurement method and a concentration measurement kit for isothiazolones that can be easily and inexpensively applied at the site where isothiazolones are actually used.

Colorimetric and fluorescent methods are highly sensitive and simple measuring methods, but isothiazolones themselves do not have a chromophore in the visible light region. As a result of intensive studies to solve the above problems, the present inventors have changed the absorption or fluorescence spectrum when isothiazolones form a reaction product with a specific metal element. Since it depends on the amount of isothiazolones present in a sample solution or the like, it has been found that the concentration of isothiazolones can be measured by measuring the spectral change. Accordingly, the present invention relates to isothiazolones in a system to be analyzed by using a group 10 or group 11 metal element as a metal element capable of changing absorption or fluorescence spectrum when forming a reaction product with isothiazolones. The present invention relates to a method for measuring the concentration, particularly preferably a method for measuring the concentration of isothiazolones in the sample solution of the system to be analyzed. That is, according to the present invention, a metal ion or a metal complex of a Group 10 or Group 11 metal element is brought into contact with an isothiazolone, and a change in absorbance or fluorescence spectrum resulting from a reaction between the metal element and the isothiazolone is measured. Provides a method for measuring the concentration of isothiazolones, characterized by determining the concentration of isothiazolones. Here, some of the “reaction products” can be confident that they are “complexes” of isothiazolones and metal elements, but we are certain that the current stage is a complex, for example, because crystals are not obtained. In some cases, the object of the present invention can be achieved if any change in absorbance or fluorescence spectrum occurs as a result of the reaction between isothiazolones and metal elements.

  Generally, when a complex is formed, the absorption / fluorescence spectrum in the ultraviolet to infrared region changes. As a mode of this change, there are a decrease or increase in a peak, the appearance of a new peak, and a peak shift. For the measurement of spectral changes, it is often sufficient for the purposes of the present invention to detect at least one of these. As a means for detecting this spectral change, typically, a method of measuring the absorbance or fluorescence intensity at a specific wavelength or a method of visually observing the color change can be mentioned. There are two types of measurement of the spectral change by the method of measuring the absorbance or fluorescence intensity at a specific wavelength. One is to measure the absorbance or fluorescence intensity after contact with a metal element (metal ion or metal complex) and to determine the concentration of isothiazolones from that value, and the other is a metal element (metal ion or metal complex) This is a method of calculating the concentration of isothiazolones from the difference between before and after contact. The latter method is used to subtract the background of the originally colored component in the sample. In the case of the former method as well, there is a calibration curve in which the state of change is measured in advance for a substantially similar analyte system, and the background component of the originally colored component specific to the analyte system is incorporated into the calibration curve. Therefore, it is possible to determine the concentration of isothiazolones from the value by detecting the spectral change only by measuring the absorbance or fluorescence intensity at a specific wavelength after contacting with a metal ion or metal complex. is there. Therefore, it can be easily understood that the spectral change can be detected by either method.

  It should be noted that the expressions “change in absorption or fluorescence spectrum when forming a reaction product with isothiazolones” and “change in absorption or fluorescence spectrum resulting from reaction of metal element with isothiazolones” ) Not only when measuring absorption / fluorescence spectra of reaction products of metal elements and isothiazolones (typically metal-isothiazolone complexes), but also when (2) metal-ligand complexes are present in the system When the ligand is substituted with isothiazolones and the absorption or fluorescence spectrum of the liberated ligand is measured, or (3) the metal-ligand complex is present in the solution system Is substituted with isothiazolones or forms a ternary complex, resulting in precipitation. For example, the precipitate is filtered as in Example 6 to be described later, and the absorbance of the metal-ligand complex remaining in the filtrate or When measuring light spectrum because some like. Therefore, “a metal element capable of changing the absorption or fluorescence spectrum when forming a reaction product with isothiazolones” means “metal” in the broad sense that it can cause “spectrum change” in the above-mentioned meaning. Of course, when a ligand other than isothiazolones is present, it may be related to the ligand.

  The isothiazolones whose concentration is to be measured in the present invention are compounds having a structure represented by the formula “Chemical Formula 1”.

[Wherein R ₁ and R ₂ are independently hydrogen, halogen, or an alkyl group having 1 to 4 carbon atoms, or together, a saturated, unsaturated or aromatic 5- or 6-membered ring. Y is hydrogen, an unsubstituted or halogen-substituted alkyl group having 1 to 18 carbon atoms, an unsubstituted or halogen-substituted alkenyl group having 2 to 8 carbon atoms, and a non-substituted group having 2 to 8 carbon atoms. Substituted or halogen-substituted alkynyl group, unsubstituted or halogen-substituted cycloalkyl group having 3 to 12 carbon atoms, unsubstituted up to 10 carbon atoms, halogen-substituted, alkyl (alkyl group has 1 to 4 carbon atoms) or substituted Alkoxy (the alkoxy group has 1 to 4 carbon atoms) substituted aralkyl group, unsubstituted up to 10 carbon atoms, halogen-substituted, alkyl (the alkyl group has 1 to 4 carbon atoms) There) the number of carbon atoms of the substituted or alkoxy (alkoxy group is a group selected from 1-4 and is) substituted aryl group. ]

  Some specific examples of the substituent Y include methyl, ethyl, propyl, butyl, hexyl, octyl, cyclohexyl, 4-methoxyphenyl, 4-chlorophenyl, 3,4-dichlorophenyl, benzyl, 4-methoxybenzyl, 4-chlorobenzyl, phenethyl, 4-phenylbutyl, chloromethyl, chloropropyl, hydrogen and the like can be mentioned.

  In addition, some specific examples of isothiazolones whose concentration is to be measured in the present invention include 2-methyl-3-isothiazolone represented by the formula “Chemical Formula 2” and 5-chloro- represented by the formula “Chemical Formula 3”. 2-methyl-3-isothiazolone, 2-n-octyl-3-isothiazolone represented by the formula “Chemical Formula 4”, 4,5-dichloro-2-cyclohexyl-3-isothiazolone represented by the formula “Chemical Formula 5”, 4,5-dichloro-2-octyl-3-isothiazolone represented by the formula of “Chemical Formula 6” and the like. These isothiazolones may be used as a mixture of two or more when used alone, but the present invention can be applied in either case.

The metal element used in the present invention may be any element that can change the absorption or fluorescence spectrum when forming a reaction product (typically a complex) with isothiazolones. The metal element suitable for such purpose is preferably a metal element having d-electrons capable of expressing various color changes and easily coordinating with oxygen or sulfur. as the element can be used at least one of the original elements of group 10 and group 11. Furthermore easy availability, from the viewpoint of easy handling, etc., as the metal element of group 10 or group 11 of the, nickel, copper, palladium, silver, platinum, at least one of gold suitable Can be used. The oxidation number of the metal element used in the present invention, for example, N i (0), Ni (II), Cu (I), Cu (II), P d (0), Pd (II), Ag (I ) , Pt (0), Pt (II), Pt (IV), and Au (III ) are preferable. These metal elements may be used as metal ions in an ionic state, or may be used as a metal complex with a ligand added in advance. Further, one kind of metal element may be used, and by using a plurality of kinds at the same time, for example, a so-called polynuclear complex containing a plurality of kinds of metal elements may be used.

  Typically, it is preferable to measure the concentration of isothiazolones contained in the sample solution by the method of the present invention. The method for measuring the concentration of isothiazolones contained in a sample solution is derived from the reaction (typically complex formation) of the metal element and isothiazolones by contacting the sample solution with a metal ion or metal complex of the metal element. This is performed through a step of causing a change in absorption or fluorescence spectrum, and a step of determining the concentration of isothiazolones by measuring the change in spectrum.

  A commercially available absorptiometer or fluorometer can be used as a method for measuring the change in absorbance or fluorescence spectrum. Here, the absorptiometer refers to a device that measures light absorption intensity at at least one wavelength, and the fluorometer excites a fluorescent substance contained in the sample solution at at least one wavelength, and An apparatus for measuring fluorescence intensity at at least one wavelength is designated. Further, as another method for measuring the change in absorbance or fluorescence spectrum, a visual method may be used.

Yet another aspect of the present invention relates to a kit for measuring the concentration of isothiazolones contained in a sample solution. Such a kit comprises (a) a metal ion or metal complex of a Group 10 or Group 11 metal element, (b) means for contacting the metal ion or metal complex with the sample solution, and (c) the metal element. Means for determining the concentration of isothiazolones by measuring the change in absorbance or fluorescence spectrum resulting from the reaction of the isothiazolones.

  In order to simplify the operation of measuring the concentration of isothiazolones contained in the sample solution, a concentration measurement kit in which a metal ion or a metal complex is fixed to a test piece in advance is also preferably used.

  The measurement conditions for measuring the concentration of isothiazolones by the method of the present invention are not particularly limited, and the measurement temperature, pH, metal concentration contained in the sample solution, and the like can be arbitrarily set. However, since the detection sensitivity of isothiazolones is affected by the measurement temperature and pH, it is desirable to perform measurement under constant measurement conditions. Moreover, it is preferable to use a buffer solution for the purpose of avoiding fluctuations in pH. In this case, as the buffering agent, those listed later can be used.

  By using the method of the present invention, it is possible to easily detect isothiazolones with high sensitivity and in a wide quantitative range. In addition, the method of the present invention can be used at a site where isothiazolones are actually used. Furthermore, since the method of the present invention has a high response speed and is easy to operate, it can be applied as a measurement method in a fully automatic continuous measurement system represented by a continuous flow analysis method (FIA: Flow Injection Analysis). It also enables continuous online detection in real time.

  Next, although the best mode for carrying out the present invention will be described, it goes without saying that the present invention is not limited to these. As for the sample solution, when sampled from the system to be analyzed is used as the sample solution as it is, when a sample (solid or liquid) sampled from the system to be analyzed is diluted with a solvent to a constant dilution rate, etc. There are various cases.

  The reaction between the isothiazolones and the metal element according to the present invention (1) appears as a spectral change such as a color change due to the formation of the reaction product (typically a metal complex). When a ligand complex is present, the ligand is substituted with isothiazolones, causing a reaction between the isothiazolones and the metal element, and appearing as a spectral change such as a color change due to liberation of the ligand, (3) When a metal-ligand complex is present in the solution system, a reaction occurs in which the ligand is replaced with isothiazolones or a ternary complex is formed, resulting in precipitation. For example, Examples described later This is involved when the precipitate is filtered as in 6 and appears as a spectral change such as a color change derived from the metal-ligand complex remaining in the filtrate. In these cases, it is possible to easily measure the concentration of isothiazolones by measuring absorbance or fluorescence spectrum. Specifically, for example, a calibration curve based on absorbance or fluorescence intensity at a specific wavelength can be prepared in advance, and a calibration curve is used from the absorbance or fluorescence intensity of a solution in which a sample solution is mixed with a metal ion or metal complex. Thus, the concentration of isothiazolones can be determined. That is, when measuring the concentration of isothiazolones, first prepare a plurality of sample solutions as series samples with known concentrations for preparing a calibration curve, and add and mix a certain amount of metal elements in the form of metal ions or metal complexes to each. Alternatively, the fluorescence intensity is measured. A calibration curve is prepared from the obtained absorbance or fluorescence intensity, and this calibration curve can be used for measurement of a sample solution whose concentration of isothiazolones is unknown.

As described above, the metal element used in the present invention is a group 10 or group 11 as a metal element that can change the absorption or fluorescence spectrum when forming a reaction product (typically a metal complex) with isothiazolones. For example, it is preferable to contain at least one of copper, palladium, silver , and platinum . These metal elements only need to dissolve in the sample solution and form a reaction product (typically a metal complex) with a spectrum change with isothiazolones. It is used in the form of a metal complex to which is added.

When a metal element is used as a metal ion, for example, a halide salt such as PdCl ₂ or a perchlorate such as Cu (ClO ₄ ) ₂ can be used.

As a ligand in the case of using a metal element as a metal complex, a compound having at least one selected from the group consisting of nitrogen, oxygen, sulfur and halogen as a coordination atom can be suitably used. The ligand may be either an inorganic ligand or an organic ligand, and may be either a monodentate ligand or a polydentate ligand. Examples of the inorganic ligand include halide ions such as NH ₃ , H ₂ O, and Cl ⁻ , OH ⁻ , NCS ⁻ , NO ₂ ⁻ , CO, and the like.

  Examples of organic ligands include bipyridyl compounds, imidazole compounds, phenanthroline compounds, ethylenediamine compounds, amino acids, triazine compounds, carbazone compounds, thiocarbazone compounds, biquinoline compounds, pyridylazo compounds, nitroso compounds, oxine compounds, benzothiazole compounds, and acetylacetone compounds. , Anthraquinone compounds, xanthene compounds, porphyrin compounds, phthalocyanine compounds, oxalic acid and the like. In addition, derivatives of the respective compounds can also be used. At least one of the hydrogen atoms other than the coordination position of the ligand may be substituted with a substituent. Examples of the substituent include an alkyl group, aryl group, allyl group, phenyl group, hydroxyl group, alkoxy group, carboxy group, carbonyl group, sulfone group, sulfonyl group, nitro group, nitroso group, secondary amino group, 3 A secondary amino group, a quaternary amino group, an amino group, an acyl group, an amide group, and a halogen group can be exemplified. It is good also as a mixed ligand complex which used the said ligand 2 or more types.

  Among these organic compound-based ligands, examples of the monodentate ligand include pyridine. Among the multidentate ligands, examples of the bidentate ligand include ethylenediamine, 1,2-propanediamine, trimethylenediamine, 2,2′-bipyridine, 1,10-phenanthroline, dithizone, acetylacetone, oxalate ion, Glycine ions and the like, and tridentate ligands such as iminodiacetic acid ion, diethylenetriamine, 2,2 ′: 6 ′, 2 ″ -terpyridine, etc., and tetradentate ligands such as triethylenetetramine and nitrilotriacetic acid ions 5,10,15,20-tetraazaporphyrin, tetraaza [14] annulene, etc., as a pentadentate ligand, hydroxyethylethylenediamine triacetate ion, etc., and as a hexadentate ligand, ethylenediaminetetraacetate ion Etc.

  A ligand having two or more kinds of coordination atoms in one ligand can also be preferably used. Examples of the ligand include 1-amino-4-hydroxyanthraquinone.

  Moreover, crown ether compounds and cryptand compounds which are macrocyclic ligands can also be suitably used. Examples of the crown ether compound include dibenzo-16-crown-6, and examples of the cryptand compound include cryptand [2, 2, 2]. A compound in which the oxygen atom which is a coordination atom is substituted with a nitrogen atom or a sulfur atom can also be suitably used. Examples of the macrocyclic ligand having a nitrogen atom as a coordination atom include cyclam, and examples of the macrocyclic ligand having a sulfur atom include 18-thiacrown-6.

  Further, for the purpose of simple concentration measurement, it can be used as a test piece in which a reagent (metal reagent, ligand reagent, etc.) necessary for measuring the concentration of isothiazolones is impregnated, adsorbed or bound to a sheet. As a result, if a color chart corresponding to various concentrations of isothiazolones is prepared as necessary, it is possible to eliminate complicated adjustment of reagents at the time of measurement only by comparison with it, and even if it is not an expert, it is accurate. Can be measured. Such a test piece preferably uses a porous material capable of holding a reagent as a support, and the reagents are applied, for example, by immersing the porous material in their solution and subsequently evaporating the liquid. Organic solvents such as methanol, ethanol, acetonitrile can be used as the solvent for the reagents, but typically aqueous solutions are used.

  As the porous material used as the support for the test piece, a porous material such as a filter paper, a glass filter, a porous ceramic piece, and a resin porous membrane can be used. Among these, filter paper is preferred for reasons such as cost and handleability. Examples of the material for the resin-made porous membrane include polysulfone, polyester, nylon, nitrocellulose, and polycarbonate. The average pore diameter of these porous materials may be, for example, that a liquid sample penetrates and is retained, and is preferably in the range of 0.1 to 10 μm, for example.

  In order to prevent the outflow of the drug, which is a constituent component contained in a test piece such as a test paper, it is possible to use a viscous agent. Typical examples of the thickener include polyvinyl alcohol, polyacrylamide, gelatin, carboxymethyl cellulose, polyvinyl pyrrolidone, sodium alginate and the like. Buffers that can be used for the purpose of avoiding fluctuations in pH include sodium citrate-sodium hydroxide, veronal sodium-hydrochloric acid, primary potassium phosphate-sodium phosphate, primary potassium phosphate-sodium hydroxide. Etc.

  The present invention will be described in more detail with reference to the following examples. However, the examples illustrate some embodiments of the present invention and do not limit the present invention in any way.

  As a sample of isothiazolones, 2-methyl-3-isothiazolone or 5-chloro-2-methyl-3-isothiazolone was used, diluted with pure water or acetonitrile and adjusted to a predetermined concentration. In “mM” and “μM”, “M” represents molar concentration, and “mL” represents milliliter.

  An acetonitrile solution containing 2-methyl-3-isothiazolone was used as a sample solution, and an acetonitrile solution in which copper (II) perchlorate hexahydrate was dissolved as a metal was added thereto. The final concentration of the sample solution was 1 to 7 mM 2-methyl-3-isothiazolone concentration and 1 mM copper (II) ion concentration. The measurement was carried out using a Hitachi U-2000A type double beam spectrophotometer. A quartz cell having an optical path length of 1 cm was used as the sample cell. The measurement results of absorbance at a wavelength of 462 nm are shown in FIG. In FIG. 1, [MI] represents 2-methyl-3-isothiazolone concentration, and “Absorbance” represents absorbance.

  As is clear from FIG. 1, the absorbance at a wavelength of 462 nm changes depending on the 2-methyl-3-isothiazolone concentration. By using this measurement result as a calibration curve, the absorbance in the sample solution of the system to be analyzed is 2- The methyl-3-isothiazolone concentration can be measured.

  Further, in this example, a sufficiently visible yellow color is produced by the complex of 2-methyl-3-isothiazolone and copper (II) ion, and its intensity depends on the 2-methyl-3-isothiazolone concentration, As the 2-methyl-3-isothiazolone concentration increased, the yellow color became stronger step by step, and it became clear that the concentration measurement by visual observation could be performed by comparison with a color chart prepared in advance as necessary.

  A filter paper was immersed in an acetonitrile solution in which copper (II) perchlorate hexahydrate was dissolved, and dried to prepare a test paper for measuring the concentration of 2-methyl-3-isothiazolone. The acetonitrile solution of copper (II) perchlorate hexahydrate was blue, but the dried test paper was almost colorless. An acetonitrile solution containing 2-methyl-3-isothiazolone was used as a sample solution, and the test paper was immersed therein. The test results are shown in Table 1.

  From the results shown in Table 1, it is possible to visually measure the concentration of 2-methyl-3-isothiazolone contained in the sample solution of the system to be analyzed by using the prepared test paper and comparing it with a color chart prepared in advance if necessary. It is clear that the concentration can be measured by a simple operation of simply immersing the test paper in the sample solution.

  An aqueous solution containing 2-methyl-3-isothiazolone was used as a sample solution, and an aqueous solution in which potassium tetrachloroplatinate (II) was dissolved as a metal was added thereto. The final concentration of the sample solution was a 2-methyl-3-isothiazolone concentration of 0.5 to 7.5 mM and a platinum (II) ion concentration of 2.5 mM. The measurement was carried out using a Hitachi U-2000A type double beam spectrophotometer. A quartz cell having an optical path length of 1 cm was used as the sample cell. The measurement results of absorbance at a wavelength of 379 nm are shown in FIG. In FIG. 2, [MI] represents 2-methyl-3-isothiazolone concentration, and “Absorbance” represents absorbance.

  As is clear from FIG. 2, the absorbance at a wavelength of 379 nm changes depending on the 2-methyl-3-isothiazolone concentration. By using this measurement result as a calibration curve, the absorbance in the sample solution of the system to be analyzed is 2- It is clear that the methyl-3-isothiazolone concentration can be measured.

  An acetonitrile solution containing 2-methyl-3-isothiazolone was used as a sample solution, and an acetonitrile solution in which copper (II) perchlorate hexahydrate as a metal and 1-methyl-4-hydroxyanthraquinone as a ligand were dissolved was used. Added. The final concentration of the sample solution was a 2-methyl-3-isothiazolone concentration of 25-250 μM, a copper (II) ion concentration of 250 μM, and a 1-methyl-4-hydroxyanthraquinone concentration of 1 mM. The measurement was carried out using a Hitachi U-2000A type double beam spectrophotometer. A quartz cell having an optical path length of 1 cm was used as the sample cell. FIG. 3 shows an absorption spectrum at a wavelength of 350 nm to 650 nm, and FIG. 4 shows a measurement result of absorbance at a wavelength of 523 nm. In FIG. 3 and FIG. 4, [MI] represents the 2-methyl-3-isothiazolone concentration, “Wavelength” represents the wavelength, and “Absorbance” represents the absorbance.

  As is clear from FIG. 3, the light absorption intensity at a wavelength of 523 nm increases as 2-methyl-3-isothiazolone contained in the sample solution increases. The absorbance at a wavelength of 523 nm was plotted against the 2-methyl-3-isothiazolone concentration. As shown in FIG. 4, the absorbance varied depending on the 2-methyl-3-isothiazolone concentration. It is clear that the 2-methyl-3-isothiazolone concentration in the sample solution of the system to be analyzed can be measured by using it as a calibration curve.

  Further, in this example, the red color became stronger with an increase in the concentration of 2-methyl-3-isothiazolone, and the change was very sensitive, so that it was found that a lower concentration of 2-methyl-3-isothiazolone can be measured. .

  The reaction mechanism in this example is that 1-methyl-4-hydroxyanthraquinone previously coordinated to copper (II) ion is converted to copper (II) by ligand exchange reaction with 2-methyl-3-isothiazolone. It is presumed that an absorption peak at 523 nm that had disappeared when desorbed from the ions and coordinated to the copper (II) ions appeared.

  An aqueous solution containing 2-methyl-3-isothiazolone was used as a sample solution, and an aqueous solution in which palladium (II) chloride was dissolved as a metal was added thereto. The final concentration of the sample solution was a 2-methyl-3-isothiazolone concentration of 8.0 mM and a palladium (II) ion concentration of 1.0 mM. For the measurement, an RF-5300PC spectrofluorometer manufactured by Shimadzu Corporation was used. A quartz cell having an optical path length of 1 cm was used as the sample cell. FIG. 5 shows a fluorescence spectrum at an excitation wavelength of 238 nm and an excitation spectrum at a fluorescence wavelength of 367 nm. For comparison, the results of the same measurement for each of an acetonitrile solution having a 2-methyl-3-isothiazolone concentration of 8.0 mM and an acetonitrile solution having a palladium (II) ion concentration of 1.0 mM are shown in FIG. As shown in FIG. 5 to 7, “Wavelength” represents a wavelength, and “Intensity” represents a fluorescence intensity.

  As is clear from FIGS. 5 to 7, in the case of each of 2-methyl-3-isothiazolone and palladium (II) ion alone, no fluorescence is observed at an excitation wavelength of 238 nm, whereas 2-methyl-3-isothiazolone and In the mixed solution of palladium (II) ions, strong fluorescence is observed at a wavelength of 367 nm. Since this fluorescence intensity depends on the 2-methyl-3-isothiazolone concentration, it is apparent that the 2-methyl-3-isothiazolone concentration can be measured using the fluorescence intensity according to the present invention.

  An acetonitrile solution containing 2-methyl-3-isothiazolone was used as a sample solution, and an acetonitrile solution in which silver (I) nitrate was dissolved as a metal and dithizone was dissolved as a ligand was added thereto. The final concentration of the sample solution was a 2-methyl-3-isothiazolone concentration of 33-260 μM, a silver (I) ion concentration of 800 μM, and a dithizone concentration of 160 μM. After mixing, the mixture was allowed to stand for 10 minutes, and then the precipitate was filtered off with a membrane filter having a pore size of 0.45 μm, and the filtrate was used for measurement. The measurement was carried out using a Hitachi U-2000A type double beam spectrophotometer. A quartz cell having an optical path length of 1 cm was used as the sample cell. FIG. 8 shows the measurement results of absorbance at a wavelength of 465 nm. In FIG. 8, [MI] indicates the 2-methyl-3-isothiazolone concentration, and “Absorbance” indicates the absorbance. .

  As is clear from FIG. 8, the absorption intensity at a wavelength of 465 nm becomes weaker as 2-methyl-3-isothiazolone contained in the sample solution increases. It is obvious that the concentration of 2-methyl-3-isothiazolone in the sample solution can be measured by using this measurement result as a calibration curve. In this example, silver (I) and dithizone form a complex, the complex has an absorption peak at a wavelength of 465 nm, and isothiazolones react with silver and precipitate. Certainly, since dithizone is not liberated, it seems that a complex of three components of silver (I) -dithizone-isothiazolone is formed.

  An acetonitrile solution containing 5-chloro-2-methyl-3-isothiazolone was used as a sample solution, and an acetonitrile solution in which copper (II) perchlorate hexahydrate was dissolved as a metal was added thereto. The final concentration of the sample solution was a 5-chloro-2-methyl-3-isothiazolone concentration of 0 to 1.8 mM and a copper (II) ion concentration of 0.6 mM. A U-2000A type double beam spectrophotometer manufactured by Hitachi, Ltd. was used for the measurement. A quartz cell having an optical path length of 1 cm was used as the sample cell. FIG. 9 shows the measurement results of absorbance at a wavelength of 300 nm. In FIG. 9, [CMI] represents 5-chloro-2-methyl-3-isothiazolone concentration, and “Absorbance” represents absorbance. .

  As is clear from FIG. 9, the absorbance at a wavelength of 300 nm varies depending on the concentration of 5-chloro-2-methyl-3-isothiazolone. By using this measurement result as a calibration curve, the sample solution of the system to be analyzed is changed. The concentration of 5-chloro-2-methyl-3-isothiazolone can be measured.

  In addition, since the absorption wavelength is different from the case of 2-methyl-3-isothiazolone, samples containing a mixture of 5-chloro-2-methyl-3-isothiazolone and 2-methyl-3-isothiazolone are also individually provided. It is possible to quantify.

[Reference Example 1]
In order to confirm that isothiazolones coordinate with metal elements to form metal complexes, the following tests were conducted. First, 0.14 mmol of copper (II) perchlorate hexahydrate was previously dissolved in about 20 mL of ethanol, 0.30 mmol of 2-methyl-3-isothiazolone was added thereto, and about 10 mL of ethanol was further added. Thereafter, the mixture was stirred for a while at room temperature. The solvent was removed, then acetone was added and the solvent was removed again. The obtained solid was washed with ethyl acetate and dried to obtain 0.014 g of an orange solid. This was recrystallized from acetone to obtain a single crystal. FIG. 10 shows the result of X-ray single crystal structure analysis of the obtained crystal. FIG. 10 is an ORTEP diagram showing a complex structure of 2-methyl-3-isothiazolone and copper (II) ion. The ORTEP diagram is a diagram created by the Oak Ridge Thermal Ellipsoid Plot (ORTEP) program. In FIG. 10, “MI” represents a 2-methyl-3-isothiazolone moiety.

  As is clear from FIG. 10, it was confirmed that 2-methyl-3-isothiazolone has an oxygen atom coordinated to a copper (II) ion.

[Reference Example 2]
In order to confirm that isothiazolones coordinate with metal elements to form metal complexes, the following tests were conducted. First, 0.023 mmol of 2-methyl-3-isothiazolone was dissolved in a dilute solution of sodium hydroxide (about 5 mL), and this was extracted with about 50 mL of chloroform. The chloroform layer was evaporated to dryness, about 30 mL of ethanol was added thereto, and silver (I) perchlorate (0.30 mmol) was added to the solution, followed by stirring for a while under dimming. The solvent was removed, a small amount of acetone was added thereto, and crystals were obtained by diffusing ether vapor into the solution. FIG. 11 shows the result of X-ray single crystal structure analysis of the obtained crystal. FIG. 11 is an ORTEP diagram showing a complex structure of 2-methyl-3-isothiazolone and silver (I) ion. In FIG. 11, “MI” represents a 2-methyl-3-isothiazolone moiety, and “ClO ₄ ” represents a ClO ₄ moiety.

  As is clear from FIG. 11, it was confirmed that 2-methyl-3-isothiazolone has an oxygen atom coordinated to a silver (I) ion.

[Reference Example 3]
In order to confirm that isothiazolones coordinate with metal elements to form metal complexes, the following tests were conducted. First, 0.13 mmol of potassium tetrachloroplatinate (II) and 0.12 mmol of dibenzo-16-crown-6 (Dibenzo-18-crown-6) represented by the following formula of “Chemical Formula 7” are dissolved in 5 mL of pure water. And stirred for 10 minutes. Thereafter, 60 mL of a chloroform solution of 2-methyl-3-isothiazolone was added to the solution (0.20 mmol of 2-methyl-3-isothiazolone was previously dissolved in 5 mL of pure water, and further neutralized by adding a sodium hydroxide solution, followed by extraction into chloroform. Solution) was added and stirred at room temperature for about 3 days. The chloroform layer colored yellow was separated and the solvent was removed to obtain yellow crystals. The result of X-ray single crystal structure analysis of the obtained crystal is shown in FIG. FIG. 12 is an ORTEP diagram showing a complex structure of 2-methyl-3-isothiazolone, a ligand, and a platinum (II) ion. In FIG. 12, “MI” represents a 2-methyl-3-isothiazolone moiety.

  As is clear from FIG. 12, it was confirmed that 2-methyl-3-isothiazolone has a sulfur atom coordinated to a platinum (II) ion.

[Reference Example 4]
In order to confirm that isothiazolones coordinate with metal elements to form metal complexes, the following tests were conducted. First, 0.1 mmol of tetrakis (acetonitrile) copper (I) perchlorate was dissolved in 3 mL of chloroform under an argon atmosphere, and 15 mL of chloroform solution of 2-methyl-3-isothiazolone (preliminarily 2-methyl-3) was added to the solution. -A solution obtained by dissolving 0.4 mmol of isothiazolone in pure water, neutralizing with sodium hydroxide solution and then extracting to chloroform, and then stirring at room temperature for 1 hour. Thereafter, 40 mL of ethyl ether was added and left for 3 months to obtain a single crystal. FIG. 13 shows the result of X-ray single crystal structure analysis of the obtained crystal. FIG. 13 is an ORTEP diagram showing a complex structure of 2-methyl-3-isothiazolone, a ligand, and a copper (II) ion. In FIG. 13, “MI” represents a 2-methyl-3-isothiazolone moiety, and “ClO ₄ ” represents a ClO ₄ moiety. .

  As is clear from FIG. 13, it was confirmed that 2-methyl-3-isothiazolone had an oxygen atom coordinated to a copper (II) ion.

  In addition, when the reference example 1 and the reference example 4 are compared, it has shown that a different complex arises with conditions. In each of the above reference examples, considerable efforts have been made to obtain complex crystals. Since the conditions for concentration measurement do not match the conditions for obtaining complex crystals, the reference example is merely an example showing that isothiazolones can form complexes with metals, but what chemical structure is used for concentration measurement? I think that is enough to demonstrate that such a complex would be formed.

  As is clear from the above description, according to the present invention, since the concentration of isothiazolones can be measured by a simple and inexpensive operation, the present invention is used in a wide range of applications in which isothiazolones are added as a bactericide or biocide. Can be applied. Specific examples of such applications include determination of isothiazolones in paper mill processing solutions, cosmetics, paints, adhesives, drugs such as pharmaceuticals and agricultural chemicals, resins, rubber, metalworking oil, industrial water, cooling water, etc. Analysis and the like.

  In addition, the method of the present invention can be applied in the field where isothiazolones are actually used, and can be applied to a fully automatic continuous measurement system by a continuous flow analysis method which has recently been attracting attention. Therefore, it is expected that the method of the present invention can be effectively applied to various water treatment systems represented by a cooling water treatment system.

It is a figure which shows the example of a measurement of the light absorbency about the sample solution of isothiazolones which added copper (II) ion. It is a figure which shows the example of a measurement of the light absorbency about the sample solution of isothiazolones which added platinum (II) ion. It is an absorption spectrum figure which shows the example of a measurement about the sample solution of isothiazolones which added copper (II) ion and 1-amino-4-hydroxyanthraquinone. It is a figure which shows the example of a measurement of the light absorbency about the sample solution of isothiazolones which added copper (II) ion and 1-amino-4-hydroxyanthraquinone. It is a fluorescence spectrum figure which shows the example of a measurement about the sample solution of isothiazolones which added palladium (II) ion. It is a fluorescence spectrum figure about the acetonitrile solution of isothiazolones. It is a fluorescence spectrum figure about the acetonitrile solution of palladium (II) ion. It is a figure which shows the measurement example of the light absorbency about the obtained filtrate by adding silver (I) ion and dithizone to the sample solution of isothiazolones, separating the produced precipitate by filtration. It is a figure which shows the example of a measurement of the light absorbency about the sample solution of other isothiazolones which added copper (II) ion. It is an ORTEP figure which shows the complex structure of isothiazolones and copper (II) ion. It is an ORTEP figure which shows the complex structure of isothiazolones and silver (I) ion. It is an ORTEP figure which shows the complex structure of isothiazolones, a ligand, and platinum (II) ion. It is another ORTEP figure which shows the complex structure of isothiazolones and copper (II) ion.

Claims (8)

The concentration of isothiazolones is determined by contacting a metal ion or metal complex of a Group 10 or Group 11 metal element with an isothiazolone and measuring a change in absorption or fluorescence spectrum resulting from the reaction of the metal element with the isothiazolone. A method for measuring the concentration of isothiazolones.   The isothiazolones are 2-methyl-3-isothiazolone, 5-chloro-2-methyl-3-isothiazolone, 2-n-octyl-3-isothiazolone, 4,5-dichloro-2-cyclohexyl-3-isothiazolone and 4 The method for measuring the concentration of isothiazolones according to claim 1, wherein the method is at least one selected from the group consisting of 1,5-dichloro-2-octyl-3-isothiazolone. The Group 10 or Group 11 metal element, copper, palladium, silver, concentration measurement method of isothiazolones according to claim 1 or 2, characterized in that at least one selected from platinum or Ranaru group . The method for measuring the concentration of isothiazolones according to any one of claims 1 to 3 , wherein the measurement of the spectral change is performed by measuring absorbance or fluorescence intensity at a wavelength of at least one point. A method for measuring the concentration of isothiazolones contained in a sample solution, wherein the sample solution is brought into contact with the metal ion or metal complex to cause a change in absorbance or fluorescence spectrum resulting from a reaction between the metal element and isothiazolones. The method for measuring the concentration of isothiazolones according to any one of claims 1 to 4 , further comprising a step of determining the concentration of isothiazolones by measuring the spectral change. The method for measuring the concentration of isothiazolones according to any one of claims 1 to 5 , wherein the measurement of the spectral change is performed visually. A kit for measuring the concentration of isothiazolones contained in a sample solution, comprising: (a) a metal ion or metal complex of a group 10 or group 11 metal element; and (b) contacting the metal ion or metal complex with the sample solution. And a means for determining the concentration of isothiazolones by measuring a change in absorbance or fluorescence spectrum resulting from the reaction between the metal element and the isothiazolones. . The kit for measuring a concentration of isothiazolones according to claim 7 , wherein the metal ion or metal complex is fixed to a test piece in advance.

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