Method for detecting aromatic organochlorine compound and detection kit

Abstract

To detect an aromatic organochlorine compound rapidly and inexpensively.SOLUTION: A method for detecting an aromatic organochlorine compound, comprising a reduction step of obtaining a first liquid by bringing an aqueous solvent into contact with a mixed liquid of a hydrophobic liquid sample and a reducing agent, and a first color development step of bringing the first liquid into contact with a first color-developing agent containing a chromogenic substrate that reacts with an aromatic organic compound having a hydroxyl group or with a second color-developing agent containing a diazonium compound.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method and a kit for detecting aromatic organic chlorine compounds. [Background technology]

[0002] Many aromatic organic chlorine compounds, such as polychlorinated biphenyls (PCBs), are known to be highly bioaccumulative and to be biologically toxic as they accumulate. For this reason, their use is sometimes restricted, and the use of polychlorinated biphenyls in particular is prohibited in Japan and other countries.

[0003] Waste containing aromatic organic chlorine compounds that was used before the regulations came into effect must be disposed of using legally appropriate methods. To implement appropriate disposal methods, it is necessary to confirm whether the waste contains aromatic organic chlorine compounds, and if so, whether the concentration of the compounds exceeds the standard value.

[0004] For example, Non-Patent Document 1 describes various simple methods for measuring polychlorinated biphenyls contained in insulating oil in transformers, capacitors, etc. Patent Document 1 also discloses a simple method for detecting polychlorinated biphenyls using immunochromatography. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-71520 [Non-patent literature]

[0006] [Non-Patent Document 1] Manual for simple measurement of trace PCBs in insulating oil (3rd edition), Industrial Waste Division, Waste and Recycling Department, Minister's Secretariat, Ministry of the Environment, May 2011 Summary of the Invention [Problem to be solved by the invention]

[0007] However, all of the simple measurement methods disclosed in Non-Patent Document 1 require dedicated equipment and take several days to a week to obtain results. The method disclosed in Patent Document 1 can obtain results within a day, but requires sample pretreatment, making it difficult to implement on-site. Furthermore, the detection method described in Patent Document 1 requires an expensive detection kit, posing an issue of high detection costs per sample.

[0008] An object of one aspect of the present invention is to provide a detection method and the like that can detect aromatic organic chlorine compounds quickly and inexpensively. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems, a method for detecting an aromatic organic chlorine compound according to one embodiment of the present invention includes a reduction step in which an aqueous solvent is brought into contact with a mixed solution of a hydrophobic liquid sample and a reducing agent to obtain a first liquid, and a first color development step in which the first liquid is brought into contact with either a first color developer containing a color-developing substrate that reacts with an aromatic organic compound having a hydroxyl group or a second color developer containing a diazonium compound.

[0010] In order to solve the above-mentioned problems, a detection kit for aromatic organic chlorine compounds according to one embodiment of the present invention comprises a reducing agent, an aqueous solvent, and at least one of a first color developer containing a chromogenic substrate that reacts with an aromatic organic compound having a hydroxyl group and a second color developer containing a diazonium compound. [Effects of the Invention]

[0011] According to one aspect of the present invention, a detection method and the like that can detect aromatic organic chlorine compounds quickly and inexpensively can be realized. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a flow chart showing an example of a method for detecting an aromatic organic chlorine compound according to a first embodiment of the present invention. [Figure 2]FIG. 3 is a flow chart showing an example of a method for detecting an aromatic organic chlorine compound according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] An embodiment of the present invention will be described in detail below. In this specification, the symbol "to" means a range of values ​​that is inclusive of both the upper and lower limits of the symbol.

[0014] [Embodiment 1. Detection Method] 1 shows an example of a method for detecting aromatic organic chlorine compounds according to one embodiment of the present invention. Hereinafter, the method for detecting aromatic organic chlorine compounds according to each embodiment may be referred to as "the present detection method." That is, "the present detection method" refers to the method for detecting aromatic organic chlorine compounds according to embodiment 1 in the description of embodiment 1, and refers to the method for detecting aromatic organic chlorine compounds according to embodiment 2 in the description of embodiment 2 described below.

[0015] (1-1. Aromatic organic chlorine compounds) The aromatic organic chlorine compounds to be detected in this detection method are compounds with an aromatic ring containing one or more chlorine atoms (chloro groups). Aromatic organic chlorine compounds are known to be lipophilic and bioaccumulate, and their accumulation can be carcinogenic, making them harmful to living organisms such as humans. Furthermore, aromatic organic chlorine compounds can be highly toxic to the environment, and therefore require appropriate management in accordance with laws and regulations.

[0016] Such aromatic organic chlorine compounds must be disposed of legally after use. Even if their use is currently prohibited, they may remain in equipment manufactured in the past when they were still usable. When disposing of such equipment, it is necessary to detect whether or not they contain aromatic organic chlorine compounds.

[0017] Various methods have been proposed for detecting aromatic organic chlorine compounds, as disclosed in, for example, Non-Patent Document 1 or Patent Document 1. However, these methods are known to have problems such as the need for dedicated equipment, the need for several days to obtain results, and the high detection cost per sample, and therefore, a rapid and inexpensive detection method is desired.

[0018] This detection method enables rapid, highly sensitive detection of aromatic organic chlorine compounds at the site where the target compound is present, without the need to bring the sample back to a laboratory or other facility. Furthermore, since it does not require specialized equipment or expensive reagents and reduces the detection cost per sample, this detection method can be applied without hesitation to samples that may contain aromatic organic chlorine compounds. This reduces the risk of overlooking detection of aromatic organic chlorine compounds. These effects also contribute to achieving the following goals in the Sustainable Development Goals (SDGs) advocated by the United Nations: Target 3.9: "Substantially reduce the number of deaths and illnesses from hazardous chemicals and air, water and soil pollution and contamination" Goal 12.4: Achieve the environmentally sound management of chemicals and all wastes and minimize their adverse impacts on human health and the environment.

[0019] Examples of aromatic organic chlorine compounds include polychlorinated biphenyls (PCBs) with 2 to 10 chlorine atoms, polychlorinated naphthalenes (PCNs) with 1 to 8 chlorine atoms, polychlorinated terphenyls (PCTs) with 1 to 14 chlorine atoms, and polychlorobenzenes with 1 to 6 chlorine atoms. The detection target in the present detection method may be at least one of these aromatic organic chlorine compounds.

[0020] Polychlorinated biphenyls are compounds in which at least one of the ten hydrogen atoms of biphenyl has been substituted with a chlorine atom. 209 isomers are known to exist, depending on the number and position of the substituted chlorine atoms. Polychlorinated biphenyls may have three or more chlorine atoms. Furthermore, the number of chlorine atoms in polychlorinated biphenyls may be nine or less, eight or less, or seven or less.

[0021] Polychlorinated naphthalene is a compound in which at least one of the eight hydrogen atoms of naphthalene has been substituted with a chlorine atom. 75 types of isomers are known to exist, depending on the number and position of the substituted chlorine atoms. The number of chlorine atoms in polychlorinated naphthalene may be two or more, or may be three or more. The number of chlorine atoms in polychlorinated naphthalene may also be eight or less. Note that monochlorinated naphthalene, which has one chlorine atom, may also be included in one aspect of polychlorinated naphthalene.

[0022] Polychlorinated terphenyls are compounds in which at least one of the 14 hydrogen atoms of a terphenyl has been substituted with a chlorine atom. 8,149 isomers are known to exist, depending on the number and position of the substituted chlorine atoms. The number of chlorine atoms in a polychlorinated terphenyl may be two or more, or may be three or more. The number of chlorine atoms in a polychlorinated terphenyl may also be 14 or less. Note that monochlorinated terphenyls, which have one chlorine atom, may also be included in one aspect of polychlorinated terphenyls.

[0023] Polychlorobenzene is a compound in which at least one of the six hydrogen atoms of benzene is substituted with a chlorine atom. The number of chlorine atoms in polychlorobenzene may be two or more, or may be three or more. The number of chlorine atoms in polychlorobenzene may be five or less. Note that monochlorobenzene, which has one chlorine atom, may also be included in one aspect of polychlorobenzene.

[0024] (1-2. Hydrophobic liquid sample) The hydrophobic liquid sample is a sample in which aromatic organic chlorine compounds are to be detected, and may be a sample that may contain aromatic organic chlorine compounds in the hydrophobic liquid.

[0025] The hydrophobic liquid may be a liquid whose solubility in water at room temperature is 1 ppm (0.0001%) or less. In this specification, room temperature refers to 20°C. Many aromatic organic chlorine compounds are poorly soluble in water, but are easily soluble in such hydrophobic liquids. Therefore, the aromatic organic chlorine compounds may remain in such hydrophobic liquids.

[0026] The hydrophobic liquid is not particularly limited, but examples thereof include insulating oil and hydrocarbon solvents. Insulating oil is a hydrophobic liquid that exhibits electrical insulating properties and is used in electrical equipment such as high-voltage transformers and high-voltage capacitors. Many electrical equipment manufactured in the past contains insulating oil containing, for example, polychlorinated biphenyls, and proper disposal is required.

[0027] The insulating oil may be, for example, an electrical insulating oil specified in at least one established or revised version of JIS C 2320. In this specification, insulating oil may also be referred to as electrical insulating oil. Di-2-ethylhexyl phthalate is also an example of insulating oil. Some of these insulating oils are also hydrocarbon solvents.

[0028] Other hydrocarbon solvents include, for example, hexane, heptane, octane, decane, and paraffin.

[0029] The hydrophobic liquid may be any one of the above-mentioned compounds, or a mixed liquid of two or more compounds. The aromatic organic chlorine compounds contained or potentially contained in the hydrophobic liquid sample may be one or two or more compounds. When the aromatic organic chlorine compounds contained in the hydrophobic liquid sample are two or more compounds, they can be detected by the present detection method as long as the total concentration of all the compounds is equal to or greater than the detection limit.

[0030] When the detection target in this detection method is a hydrophobic liquid, for example, insulating oil suspected of containing aromatic organic chlorine compounds may be used as a hydrophobic liquid sample as is. Also, when the detection target is a hydrophilic liquid such as an aqueous solution of aromatic organic chlorine compounds, an extraction step may be first carried out in which the aromatic organic chlorine compounds are extracted into the hydrophobic liquid by, for example, mixing the hydrophilic liquid with a hydrophobic liquid.

[0031] An example of such a case is the detection of aromatic organic chlorine compounds as pesticides or the like dispersed in an aqueous solution such as environmental water. Aromatic organic chlorine compounds are generally hydrophobic and therefore easily soluble in hydrophobic liquids. Therefore, aromatic organic chlorine compounds dispersed in a hydrophilic liquid can be easily extracted into the hydrophobic liquid.

[0032] For example, polychlorinated biphenyls and polychlorinated naphthalenes may be contained in insulating oils of electrical equipment and heat transfer media of heat exchangers, etc. Such insulating oils may be used as they are as hydrophobic liquid samples.

[0033] Furthermore, for example, polychlorobenzenes have been used in the past or are still used today as precursors of insecticides and pesticides. Therefore, at least some types of polychlorobenzenes may be targets for detection in environmental pollution testing. This detection method can be suitably used to detect polychlorobenzenes and the like by extracting aromatic organic chlorine compounds from environmental water into a hydrophobic liquid, for example.

[0034] This detection method includes a reduction step and a first color-developing step, and may further include a second color-developing step. This detection method may also include the extraction step described above. Figure 1 is a flow chart showing an example of this detection method. Hereinafter, this detection method will be described with reference to Figure 1.

[0035] (1-3. Reduction process) The reduction step is a step in which an aqueous solvent is brought into contact with a mixture of a hydrophobic liquid sample and a reducing agent to obtain a first liquid.

[0036] The reducing agent may be a substance having a function of reducing the aromatic organic chlorine compound by a substitution reaction with the chlorine atom thereof. The reducing agent may be, for example, metallic sodium or a compound containing an alkali metal. The compound containing an alkali metal may be a compound containing sodium or potassium, and examples thereof include sodium biphenyl, potassium biphenyl, sodium naphthalenide, potassium naphthalenide, sodium cyclopentadienyl, and potassium cyclopentadienyl.

[0037] The reducing agent may also contain an alkali metal or alkaline earth metal other than those mentioned above. More specifically, the reducing agent may be a liquid in which such an alkali metal or alkaline earth metal is dissolved in a solvent with high electron donating properties. It is known that such a liquid can be used as a reducing agent exhibiting strong reducing action. In this case, the alkali metal or alkaline earth metal may be sodium, potassium, lithium, or calcium. The solvent with high electron donating properties may be liquid ammonia, alkylamine, or hexamethylphosphoric amide.

[0038] The aqueous solvent may be water or a mixed solvent of water and alcohol. The aqueous solvent may also contain components other than water and alcohol. The components other than water and alcohol may be, for example, an oxidizing agent or a pH adjuster, which will be described later.

[0039] The water may be pure water, ion-exchanged water, or distilled water, or may contain impurities such as tap water, etc. Examples of alcohol include methanol and ethanol.

[0040] The amount of water contained in the aqueous solvent is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 25% by mass or more, and even more preferably 50% by mass or more.

[0041] In the reduction step, first, a hydrophobic liquid sample and a reducing agent are mixed to obtain a mixed solution (S1). The following describes an example in which a reducing agent containing sodium is used as the reducing agent. In S1, for example, the reducing agent may be added to the hydrophobic liquid sample. The resulting mixed solution is preferably allowed to stand for a while at room temperature to allow the reduction reaction to proceed. The standing time may be set appropriately, for example, for 5 minutes.

[0042] Next, an aqueous solvent is brought into contact with the mixed liquid to obtain a first liquid (S2). The method of contact is not particularly limited, but for example, the aqueous solvent may be added to the mixed liquid, or the mixed liquid may be added to the aqueous solvent. Alternatively, the aqueous solvent and the mixed liquid may be mixed.

[0043] In the reduction step, if the hydrophobic liquid sample contains an aromatic organic chlorine compound, the aromatic organic chlorine compound is reduced, and the chlorine atom is replaced with a sodium atom. Then, when the aromatic organic compound that has lost the chlorine atom comes into contact with the aqueous solvent, the sodium atom is replaced with a hydroxyl group, and the reduction reaction is stopped.

[0044] After the reduction step is completed, the first liquid is separated into a hydrophobic liquid phase and an aqueous phase. In this specification, the aqueous phase refers to the phase formed by the aqueous solvent in the first liquid, and the solvent constituting the aqueous phase may contain a solvent other than water. In the first liquid, the aromatic organic compound having a hydroxyl group is contained in the aqueous phase. The aromatic organic compound having a hydroxyl group is, for example, a phenol.

[0045] (1-4. First coloring process) The first color-developing step may be a step (S3) of contacting the first liquid with a first color-developing agent containing a color-developing substrate that reacts with an aromatic organic compound having a hydroxyl group.

[0046] The chromogenic substrate contained in the first color former may be, for example, a compound that substitutes for the hydroxyl group of an aromatic organic compound having a hydroxyl group, bonds to an aromatic organic chlorine compound, and exhibits color development. Examples of such chromogenic substrates include aminopyrine, aminoantipyrine, and 3-aminopyrazone. The chromogenic substrate contained in the first color former may also be a chromogenic substrate that reacts with an aromatic organic compound having a hydroxyl group through other mechanisms to develop color. The first color former may be, for example, the chromogenic substrate itself in a solid form such as powder, or may be an aqueous solution in which the chromogenic substrate is dissolved in an aqueous solvent.

[0047] When the color-developing substrate contained in the first color developer is aminopyrine, aminoantipyrine, or the like, it is preferable to carry out the reaction in the presence of an oxidizing agent from the viewpoint of rapid and satisfactory color development. Therefore, in at least one of the reduction step and the first color-developing step, an oxidizing agent may be further mixed with the first liquid. When the first liquid and the oxidizing agent are mixed in the reduction step, the oxidizing agent may be contained in an aqueous solvent or may be added to the first liquid.

[0048] The oxidizing agent is not particularly limited as long as it promotes the reaction between the color-developing substrate of the first color former and the aromatic organic compound having a hydroxyl group, and examples thereof include potassium peroxodisulfate, potassium ferricyanide, and hydrogen peroxide. The oxidizing agent may be in liquid or solid form. An example of a liquid oxidizing agent may be an aqueous solution in which the oxidizing agent is dissolved in an aqueous solvent.

[0049] When the color-developing substrate contained in the first color developer is aminopyrine, aminoantipyrine, or the like, it is preferable to make the first liquid basic in terms of rapid and good color development. Therefore, in at least one of the reduction step and the first color-developing step, a pH adjuster may be further mixed with the first liquid so that the pH of the aqueous phase of the first liquid is greater than 7.0. When the first liquid and the pH adjuster are mixed in the reduction step, the pH adjuster may be contained in the aqueous solvent added to the mixed liquid, or may be added to the first liquid.

[0050] The pH adjuster may be in liquid or solid form. Liquid pH adjusters may be basic liquids such as aqueous sodium hydroxide solution, aqueous potassium hydroxide solution, and aqueous sodium carbonate solution, or may be pH buffers such as phosphate buffers that have pH buffering capacity in a pH range greater than 7.0. Solid pH buffer materials may be substances that, when mixed with an aqueous solvent, turn the aqueous solvent into the basic liquid or pH buffer.

[0051] The oxidizing agent and pH adjuster may be mixed with the first liquid in a mixed state. For example, a liquid obtained by mixing the oxidizing agent and an aqueous sodium hydroxide solution may be mixed with the first liquid (S4). When the oxidizing agent and pH adjuster are mixed with the first liquid in the first color-forming step, they may be mixed with the first liquid after contacting with the first color former, or they may be mixed with the first liquid before contacting with the first color former.

[0052] Next, the appearance of the first liquid that has come into contact with the first color former is observed. When the color-developing substrate of the first color former is aminopyrine, aminoantipyrine, or 3-aminopyrazone, it is determined whether the appearance of the first liquid is pink (S5). The type of color determined here may be appropriately determined depending on the type of color-developing substrate of the first color former. After contacting the first liquid with the first color former, it is preferable to allow the reaction to proceed for a while before observing the appearance. During the reaction, the first liquid may be left to stand or may be stirred by inversion or the like. The reaction time may be appropriately determined depending on the type of color-developing substrate of the first color former, and may be, for example, 3 minutes. The reaction may be carried out at room temperature.

[0053] If the first liquid has a pink appearance (yes in S5), it is determined that an aromatic organic chlorine compound has been detected (S6). In other words, it can be determined that the hydrophobic liquid sample contains an aromatic organic chlorine compound. If this determination is made, the detection method may be terminated.

[0054] (1-5. Second coloring process) If the appearance of the first liquid is not pink (no in S5), for example, if the appearance of the first liquid is colorless and transparent or if the color is different from the color of the reaction of the chromogenic substrate of the first color developer, a second color development step may be further performed. In this case, it is impossible to determine whether the hydrophobic liquid sample did not contain any aromatic organic chlorine compounds or whether the concentration of aromatic organic chlorine compounds contained in the hydrophobic liquid sample was below the detection limit of the first color developer. Therefore, it is preferable to further perform a second color development step.

[0055] The second color-forming step may be a step (S7) of contacting the first liquid with a second color former.

[0056] The second color former may include a diazonium compound. The diazonium compound may react with an aromatic organic compound to develop color, for example, by a diazo coupling reaction. In the second color development step of this embodiment, the aromatic organic compound derivatized with the color-developing substrate of the first color former becomes the target of reaction for the diazonium compound.

[0057] Such diazonium compounds are preferably aromatic diazonium compounds, and examples thereof include 4-diazodiphenylamine sulfate and 4-diazo-N,N-dimethylaniline chloride zinc chloride.

[0058] The second color former may be a diazonium compound itself, or may be an aqueous solution in which a diazonium compound is dissolved in an aqueous solvent.

[0059] In the reaction with the second color former, it is preferable that an oxidizing agent and a pH adjuster are mixed into the first liquid from the viewpoint of rapid and good color development. If the first liquid is not mixed with an oxidizing agent and / or a pH adjuster in the reduction step and the first color development step, the first liquid may be mixed with an oxidizing agent and / or a pH adjuster in the second color development step.

[0060] Next, the appearance of the first liquid that has been brought into contact with the first color former and then the second color former is observed. Specifically, it is determined whether the appearance of the first liquid is brown (S8). After bringing the first liquid into contact with the second color former, it is preferable to allow the reaction to proceed for a while before observing the appearance. The reaction time can be set appropriately, and may be, for example, 3 minutes. The reaction may be carried out at room temperature.

[0061] If the first liquid has a brownish-red appearance (yes in S8), it is determined that an aromatic organic chlorine compound has been detected (S6). In other words, it can be determined that the hydrophobic liquid sample contains an aromatic organic chlorine compound. On the other hand, if the first liquid has a brown appearance (no in S8), it is determined that an aromatic organic chlorine compound has not been detected (S9). The brown color is thought to be due to unreacted diazonium compound. Therefore, in this case, it can be determined that the first liquid does not contain any aromatic organic compounds that can react with the diazonium compound, or that the amount of aromatic organic compounds contained is so small that it does not pose a problem in terms of regulations, etc.

[0062] This detection method may include a second color-developing step in addition to the first color-developing step as described above. When the hydrophobic liquid sample contains an aromatic organic chlorine compound in an amount detectable by the first color-developing agent, the aromatic organic chlorine compound can be detected extremely quickly by carrying out the reduction step and the first color-developing step.

[0063] Furthermore, if the hydrophobic liquid sample contains only trace amounts of aromatic organic chlorine compounds, the color development by the first color developer may be difficult to visually confirm, i.e., below the detection limit. Even in this case, by further performing a second color development step, the color development by the first color developer and the color development by the second color developer complement each other, making it possible to lower the lower limit of the detectable amount. In particular, if the aromatic organic chlorine compound has a small number of chlorine atoms, it is difficult for the first color developer to produce color, so complementation by the color development by the second color developer is effective.

[0064] According to this detection method, aromatic organic chlorine compounds can be detected with high sensitivity. Furthermore, since the second color development step usually takes only a few minutes, detection can be performed more quickly than conventional methods, even when the second color development step is performed.

[0065] For example, in Japan, industrial waste containing 0.5 mg / kg or more of polychlorinated biphenyls is required to be disposed of in accordance with the law. This detection method can detect even 0.5 mg / kg of polychlorinated biphenyls contained in hydrophobic liquids such as insulating oil.

[0066] [Embodiment 2: Other Detection Methods] Another embodiment of the present invention will be described below. For the sake of convenience, the contents described in the first embodiment will not be described again. FIG. 2 shows an example of a method for detecting aromatic organic chlorine compounds according to this embodiment. This embodiment differs from the first embodiment in that a second color former is used in the first color-developing step and a first color former is used in the second color-developing step.

[0067] 2, in the first color-developing step after obtaining the first liquid in the reduction step, the first liquid may be brought into contact with the second color former (S13). That is, the first color-developing step may be a step in which the first liquid is brought into contact with either the first color former or the second color former. In other words, the second color former may be brought into contact with the first liquid before the first color former.

[0068] Even when the second color former is brought into contact with the first liquid in the first color-developing step, it is preferable that the step (S4) of mixing the first liquid with an oxidizing agent and / or a pH adjuster is carried out before observing the color development by the second color former.

[0069] Next, it is determined whether the appearance of the first liquid is brownish-red (S15). If the appearance of the first liquid is brownish-red, or after contacting the first liquid with the second color former, it is preferable to allow the reaction to proceed for a while before observing the appearance. The reaction time may be set appropriately, and may be, for example, 5 minutes. The reaction may be carried out at room temperature.

[0070] If the appearance of the first liquid is brown (yes in S15), it is determined that an aromatic organic chlorine compound has been detected (S6). In other words, it can be determined that the hydrophobic liquid sample contains an aromatic organic chlorine compound. If this determination is made, the detection method may be terminated.

[0071] If the appearance of the first liquid is not brown (no in S15), a second color-developing step may be further carried out. In this case, it is not possible to determine whether the hydrophobic liquid sample contained no aromatic organic chlorine compounds or whether the concentration of the aromatic organic chlorine compounds contained in the hydrophobic liquid sample was below the detection limit of the second color developer. Therefore, it is preferable to further carry out the second color-developing step.

[0072] The second color-developing step may be a step (S17) of contacting the first liquid with the first color-developing agent. That is, in the second color-developing step, if the first color-developing agent is used in the first color-developing step, the second color-developing agent may be used, and in the case where the second color-developing agent is used in the first color-developing step as in this embodiment, the first color-developing agent may be used.

[0073] In the second color-forming step of this embodiment, an aromatic organic compound having a hydroxyl group, which is a derivative of the reaction with the second color former, becomes the reaction target of the color-forming substrate of the first color former. As long as the aromatic organic compound has a hydroxyl group, the color-forming substrate of the first color former can develop color even if it is derivatized with the second color former.

[0074] Next, the appearance of the first liquid that has been contacted with the second color former and then the first color former is observed. If the color-developing substrate of the first color former is aminopyrine or aminoantipyrine, it is determined whether the appearance of the first liquid is brown (S18). After contacting the first liquid with the second color former, it is preferable to allow the reaction to proceed for a while before observing the appearance. During the reaction, the first liquid may be left to stand or may be stirred by inversion or the like. The reaction time may be set appropriately, and may be, for example, 3 minutes. The reaction may be carried out at room temperature.

[0075] If the first liquid has a brownish-red appearance (yes in S18), it is determined that an aromatic organic chlorine compound has been detected (S6). In other words, it can be determined that the hydrophobic liquid sample contains an aromatic organic chlorine compound. When the first liquid is brown when it is brought into contact with the second color developer, and when it is further brought into contact with the first color developer, color development by the first color developer occurs, and the pink color developed by the first color developer overlaps with the brown color of the second color developer, resulting in a brownish-red color.

[0076] On the other hand, if the appearance of the first liquid remains brown (no in S18), it is determined that no aromatic organic chlorine compounds have been detected (S9).

[0077] [Embodiment 3: Detection Kit] One embodiment of the present invention includes a detection kit for aromatic organic chlorine compounds. In this specification, the detection kit according to one embodiment of the present invention is referred to as the "detection kit." The detection kit includes a reducing agent, an aqueous solvent, and at least one of a first color developer and a second color developer.

[0078] The aqueous solvent included in the detection kit may be water, a mixed solvent of water and alcohol, etc. When the aqueous solvent is a mixed solvent of water and alcohol, the detection kit may include a mixed solvent of water and alcohol, or may include water and alcohol separately.

[0079] The detection kit may further comprise an oxidizing agent and a pH buffering agent.

[0080] The detection kit may contain each of the reducing agent, the first color developer, the second color developer, the oxidizing agent, and the pH buffering material in the form of a solution such as an aqueous solution, or in the form of a solid such as a powder. When at least one of the reducing agent, the first color developer, the second color developer, the oxidizing agent, and the pH buffering material is a solid, the detection kit may further contain a solvent suitable for dissolving the solid.

[0081] The detection kit may further include other components. Examples of such components include, but are not limited to, a collection container for collecting a hydrophobic liquid sample, a preparation container for preparing the first liquid, other containers, kit instructions, and a color sample. The preparation container for preparing the first liquid is preferably colorless and transparent to facilitate confirmation of color development in the first or second color development step.

[0082] 〔summary〕 The method for detecting an aromatic organic chlorine compound according to the first aspect of the present invention includes a reduction step in which an aqueous solvent is brought into contact with a mixed solution of a hydrophobic liquid sample and a reducing agent to obtain a first liquid, and a first color development step in which the first liquid is brought into contact with either a first color developer containing a color-developing substrate that reacts with an aromatic organic compound having a hydroxyl group or a second color developer containing a diazonium compound.

[0083] The method for detecting an aromatic organic chlorine compound according to Aspect 2 of the present invention is the same as in Aspect 1, and further includes a second color-developing step of contacting the first liquid with the first color-developing agent or the second color-developing agent, and in the second color-developing step, if the first color-developing agent is used in the first color-developing step, the second color-developing agent may be used, and if the second color-developing agent is used in the first color-developing step, the first color-developing agent may be used.

[0084] A method for detecting an aromatic organic chlorine compound according to aspect 3 of the present invention is the same as that according to aspect 1 or 2, and the aromatic organic chlorine compound may be at least one selected from the group consisting of polychlorinated biphenyls having 2 to 10 chlorine atoms, polychlorinated naphthalenes having 1 to 8 chlorine atoms, polychlorobenzenes having 1 to 6 chlorine atoms, and polychlorinated terphenyls having 1 to 14 chlorine atoms.

[0085] The method for detecting an aromatic organic chlorine compound according to Aspect 4 of the present invention may be the same as Aspect 2, except that an oxidizing agent may be further mixed with the first liquid in at least one of the reduction step, the first color-developing step, and the second color-developing step.

[0086] The method for detecting an aromatic organic chlorine compound according to aspect 5 of the present invention, in aspect 2 or 4, may further comprise mixing a pH adjuster with the first liquid in at least one of the reduction step, the first color-development step, and the second color-development step so that the pH of the aqueous phase of the first liquid is greater than 7.0.

[0087] A kit for detecting aromatic organic chlorine compounds according to a sixth aspect of the present invention comprises a reducing agent, an aqueous solvent, and at least one of a first color developer containing a chromogenic substrate that reacts with an aromatic organic compound having a hydroxyl group and a second color developer containing a diazonium compound.

[0088] [Additional Notes] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Example]

[0089] An example of the method for detecting aromatic organic chlorine compounds according to one embodiment of the present invention will be described below.

[0090] (material) The hydrophobic liquid sample used was a sample in which an aromatic organic chlorine compound was dissolved in a hydrophobic liquid. The hydrophobic liquid used was electrical insulating oil (IO, HS Transformer N manufactured by ENEOS Corporation, main component: mineral oil) or hexane (HEX, CAS: 110-54-3). The electrical insulating oil was selected to simulate the electrical insulating oil used in transformers and capacitors containing polychlorinated biphenyls. Hexane was selected with the expectation that chlorinated pesticides dispersed in an aqueous solution would be extracted into the hydrophobic liquid.

[0091] The aromatic organic chlorine compounds used for detection were chlorobenzene (CB, CAS: 108-90-7), dichlorobenzene (DCB, CAS: 95-50-1), polychlorinated biphenyls (PCB, CAS: 1336-36-3), polychlorinated naphthalenes (PCN, CAS: 70776-03-3), and polychlorinated terphenyls (PCT, CAS: 61788-33-8). These aromatic organic chlorine compounds were dissolved in hydrophobic liquids as shown in Tables 1 to 3 to prepare hydrophobic liquid samples.

[0092] The reducing agent used was sodium biphenyl (BS, CAS: 5137-46-2), which can efficiently reduce chlorine atoms substituted on aromatic rings in a short time at room temperature.

[0093] The chromogenic substrates used for the first color developer were aminoantipyrine (AMP, CAS: 83-07-8), aminopyrine (AP, CAS: 58-15-1), or 3-aminopyrazone (3-APY, CAS: 1820-80-0). These chromogenic substrates bond with aromatic organic compounds containing hydroxyl groups to form derivatives, which produce a pink color. Aqueous solutions of these chromogenic substrates were used as the first color developer. In this example, aqueous solutions refer to solutions in water or a mixed solvent of water and ethanol.

[0094] The second color coupler used was an aqueous solution of 4-diazodiphenylamine sulfate (DAPS, CAS: 4477-28-5) or 4-diazo-N,N-dimethylaniline chloride zinc chloride (DMA-Zn, CAS: 6087-56-5). These second color couplers bond with aromatic organic compounds that have hydroxyl groups and / or the color-forming substrate of the first color coupler as a substituent, forming derivatives that produce a brownish color.

[0095] The oxidizing agents used were potassium peroxodisulfate (KPS, CAS: 7727-21-1) or potassium ferricyanide (PFC, CAS: 13746-66-2), dissolved in aqueous sodium hydroxide, which acted as a pH adjuster.

[0096] (method) First, a reducing agent was added to a hydrophobic liquid sample containing aromatic organic chlorine compounds to obtain a mixed solution. The resulting mixed solution was allowed to stand at room temperature for approximately 5 minutes to reduce the aromatic organic chlorine compounds. Next, water was added to the mixed solution after standing to obtain the first liquid, thereby terminating the reduction reaction caused by the reducing agent.

[0097] Either the first color former or the second color former aqueous solution was added to the first liquid and mixed thoroughly, after which an aqueous sodium hydroxide solution containing an oxidizing agent was added and the mixture was left to stand at room temperature for 3 minutes. After standing, the appearance of the aqueous phase of the first liquid was visually observed. If the aqueous phase of the first liquid turned pink when the first color former was used, or if the aqueous phase of the first liquid turned brown when the second color former was used, it was determined that aromatic organic chlorine compounds had been detected.

[0098] On the other hand, if the aqueous phase of Liquid 1 was colorless, transparent, or brown, or if it was a color other than brown or pink, either the first or second color former was added to Liquid 1, and the mixture was allowed to stand at room temperature for another 3 minutes. The aqueous phase of Liquid 1 was then visually observed, and if it turned brown, it was determined that aromatic organic chlorine compounds had been detected. If the aqueous phase of Liquid 1 was brown or a color other than brown, it was determined that aromatic organic chlorine compounds had not been detected. If insoluble matter was present in the aqueous phase of Liquid 1, it was deemed impossible to determine.

[0099] In all examples and comparative examples, both the method of adding the first color former first (referred to as the first → second color former) and the method of adding the second color former first (referred to as the second → first color former) were carried out and evaluated respectively.

[0100] (result) The conditions and results of each example and comparative example are shown in the following Tables 1 to 5. The results are shown as "detected" when an aromatic organic chlorine compound was detected in the hydrophobic liquid sample, "not detected" when it was not detected, and "error" when it was impossible to determine.

[0101] [Table 1]

[0102] [Table 2]

[0103] [Table 3]

[0104] [Table 4]

[0105] [Table 5]

[0106] As shown in Tables 1 to 5, aromatic organic chlorine compounds were detected in all of the Examples based on this detection method. In particular, it was shown that this detection method can detect even trace amounts of aromatic organic chlorine compounds, such as CB and PCB, at 0.05 mg / kg. On the other hand, in each of the Comparative Examples in which any of the conditions differed from those of this detection method, aromatic organic chlorine compounds could not be detected or could not be determined.

[0107] As shown in the reference examples in Table 5, it is preferable to use an oxidizing agent and a pH adjuster. However, the oxidizing agent improves sensitivity and is not essential for detecting aromatic organic chlorine compounds. Furthermore, the pH adjuster is not essential when the pH of the hydrophobic liquid containing the aromatic organic chlorine compounds is greater than 7. [Industrial Applicability]

[0108] The present invention can be used to detect aromatic organochlorine compounds such as PCBs.

Claims

1. a reducing step of contacting an aqueous solvent with a mixture of a hydrophobic liquid sample and a reducing agent to obtain a first liquid; a first color-developing step of contacting the first liquid with either a first color-developing agent containing a color-developing substrate that reacts with an aromatic organic compound having a hydroxyl group or a second color-developing agent containing a diazonium compound.

2. a second color-forming step of contacting the first liquid with the first color-forming agent or the second color-forming agent, In the second color-developing step, When the first color former is used in the first color-developing step, the second color former is used, 2. The method for detecting an aromatic organic chlorine compound according to claim 1, wherein when the second color former is used in the first color-developing step, the first color former is used.

3. 3. The method for detecting an aromatic organic chlorine compound according to claim 1, wherein the aromatic organic chlorine compound is at least one selected from the group consisting of polychlorinated biphenyls having 2 to 10 chlorine atoms, polychlorinated naphthalenes having 1 to 8 chlorine atoms, polychlorobenzenes having 1 to 6 chlorine atoms, and polychlorinated terphenyls having 1 to 14 chlorine atoms.

4. 3. The method for detecting an aromatic organic chlorine compound according to claim 2, wherein an oxidizing agent is further mixed with the first liquid in at least one of the reducing step, the first color-developing step, and the second color-developing step.

5. 5. The method for detecting an aromatic organic chlorine compound according to claim 2, wherein in at least one of the reduction step, the first color-developing step, and the second color-developing step, a pH adjuster is further mixed with the first liquid so that the pH of the aqueous phase of the first liquid is higher than 7.

0.

6. A kit for detecting aromatic organic chlorine compounds, comprising a reducing agent, an aqueous solvent, and at least one of a first color developer containing a color-developing substrate that reacts with an aromatic organic compound having a hydroxyl group and a second color developer containing a diazonium compound.

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