Chemical sensor for detecting sulfide, hydrogen sulfide detection kit including same, and method for preparing same

Abstract

The present disclosure relates to a ferrocene-based compound having high selectivity for sulfide ion. The ferrocene-based compound is obtained by reacting a ferrocene starting material with one or more organic compound selected from a nitrile, a methyl ester and an ethyl ester, and a chemical sensor in solution state is prepared by mixing the compound with an organic solvent. The chemical sensor according to the present disclosure has high selectivity and sensitivity for sulfide ion even at low concentration and may be used as a chemical sensor for detecting hydrogen sulfide in solution state by allowing visual inspection of sulfide ion. In addition, the present disclosure provides a hydrogen sulfide detection kit including an airtight container including an opening/closing door and a detection material inlet, a detection unit which is provided inside the airtight container and composed of paper or fabric to which a ferrocene compound is adsorbed, and a basic reagent which is stored inside or outside the airtight container and generates sulfide ion from hydrogen sulfide. According to the present disclosure, hydrogen sulfide can be detected in real time by generating sulfide ion from hydrogen sulfide in gas or liquid state and visually inspecting the color change of the ferrocene compound of the detection kit.

Claims

1. A sulfide ion-selective chemical sensor comprising a ferrocene-based compound represented by Chemical Formula 1 and showing color change by selectively reacting with sulfide ion: ##STR00009## wherein each of R.sup.1 and R.sup.2 is independently an organic compound selected from nitrile (CN), methyl ester (CO.sub.2Me) and ethyl ester (CO.sub.2Et) and, R.sup.1 and R.sup.2 may be identical to or different from each other.

2. The chemical sensor according to claim 1, wherein, in the compound represented by Chemical Formula 1, both R.sup.1 and R.sup.2 are nitrile (CN).

3. The chemical sensor according to claim 1, wherein 0.001-1.00% (w/v) of the compound represented by Chemical Formula 1 is dissolved in one or more organic solvent selected from saturated or unsaturated hydrocarbons, ethers, esters, alcohols, amines and ketones.

4. A hydrogen sulfide detection kit comprising: an airtight container comprising an opening/closing door and a detection material inlet; a detection unit which is provided inside the airtight container and composed of paper or fabric to which a ferrocene compound is adsorbed; and a basic reagent which is stored inside or outside the airtight container and generates sulfide ion from hydrogen sulfide, wherein the ferrocene compound is represented by Chemical Formula 1: ##STR00010## wherein each of R.sup.1 and R.sup.2 is independently an organic compound selected from nitrile (CN), methyl ester (CO.sub.2Me) and ethyl ester (CO.sub.2Et).

5. The hydrogen sulfide detection kit according to claim 4, wherein the basic reagent which generates sulfide ion by reacting with hydrogen sulfide is any one selected from LiOH, NaOH, KOH, Mg(OH).sub.2, Ca(OH).sub.2, trimethylamine, triethylamine, pyridine and piperidine.

6. The hydrogen sulfide detection kit according to claim 4, which is equipped with a transparent window on the surface of the airtight container, which allows the inspection of the color change of the detection unit due to hydrogen sulfide solution introduced to the detection unit or hydrogen sulfide gas exposed to the detection unit.

7. The hydrogen sulfide detection kit according to claim 4, wherein the basic reagent is stored in a capsule-type container provided at one side of the detection unit and is dropped or coated onto the ferrocene compound of the detection unit as the capsule is broken.

8. The hydrogen sulfide detection kit according to claim 4, wherein the basic reagent is provided inside the airtight container as being spaced apart from the detection unit or is stored on the outer surface of the airtight container, and the reagent is coated or introduced to the detection unit during detection of hydrogen sulfide.

9. A method for detecting hydrogen sulfide using a detection kit comprising an airtight container comprising an opening/closing door and a detection material inlet, a detection unit which is provided inside the airtight container and composed of paper or fabric to which a ferrocene compound is adsorbed, and a basic reagent which generates sulfide ion from hydrogen sulfide, wherein the ferrocene compound is represented by Chemical Formula 1: ##STR00011## wherein each of R.sup.1 and R.sup.2 is independently an organic compound selected from nitrile (CN), methyl ester (CO.sub.2Me) and ethyl ester (CO.sub.2Et), wherein the basic reagent is coated or introduced into the detection unit, a part of the detection unit is drawn out of the airtight container by partially opening the airtight container and then is exposed to hydrogen sulfide solution or hydrogen sulfide gas, or hydrogen sulfide solution or hydrogen sulfide gas is introduced into the inlet, and the presence of hydrogen sulfide is judged by the color change of the detection unit from violet to yellow.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

(2) FIG. 1 shows the color change of a ferrocene-based chemical sensor of the present disclosure in response to reaction with various anions.

(3) FIG. 2 shows the change in the UV-Vis spectrum of a chemical sensor.

(4) FIGS. 3A and 3B show chemical formulas and UV-Vis spectrum peaks before introduction of sulfide ion.

(5) FIGS. 4A and 4B show chemical formulas and UV-Vis spectrum peaks after introduction of sulfide ion.

(6) FIG. 5 shows the change in the absorption wavelength of the UV-Vis spectrum of a chemical sensor depending on the concentration of sulfide ion.

(7) FIG. 6 shows the existing apparatuses for gas analysis and sulfide ion identification.

(8) FIGS. 7A and 7B show a detection test for hydrogen sulfide gas.

(9) FIGS. 8A and 8B show a detection test for hydrogen sulfide solution.

(10) FIG. 9 shows a detection test for sulfide ion solution.

(11) FIG. 10 schematically shows a hydrogen sulfide detection kit according to an exemplary embodiment of the present disclosure.

(12) FIG. 11 schematically shows a hydrogen sulfide detection kit according to another exemplary embodiment of the present disclosure.

BEST MODE

(13) The present disclosure provides a ferrocene-based compound having high selectivity and superior sensitivity for a specific anion, a chemical sensor (chemosensor) using the same, and a method for preparing the same.

(14) More specifically, the present disclosure provides a ferrocene-based chemical sensor, which is prepared economically by synthesizing a ferrocene-based compound and diluting the same in an organic solvent and allows visual inspection of the color change of an aqueous sulfide ion solution.

(15) The present disclosure provides a ferrocene-based compound represented by Chemical Formula 1 as a chemical sensor having high selectivity and sensitivity for sulfide ion (S.sup.2−), which is a source of hydrogen sulfide (H.sub.2S).

(16) ##STR00002##

(17) In Chemical Formula 1, each of R.sup.1 and R.sup.2 is independently an organic compound selected from nitrile (CN), methyl ester (CO.sub.2Me) and ethyl ester (CO.sub.2Et) and, R.sup.1 and R.sup.2 may be identical to or different from each other.

(18) The ferrocene-based compound of Chemical Formula 1 can be mass-produced economically and stably using a commercially available ferrocene compound and an organic compound as starting materials. As an example of the method for preparing the ferrocene-based compound of the present disclosure, the ferrocene-based compound may be prepared through a reaction according to Chemical Formula 1. After reacting a ferrocene starting material and an organic compound at an equimolar ratio in a solvent, the final compound is obtained by filtering the produced solid product and removing the solvent under reduced pressure.

(19) ##STR00003##

(20) A specific example of the produced final compound is shown in Chemical Formula 2, wherein both the organic compounds (R.sup.1, R.sup.2) are nitrile (CN).

(21) ##STR00004##

(22) The chemical sensor for detecting sulfide ion may be prepared by dissolving a ferrocene-based compound in an organic solvent. For example, a composition including 0.001-1.00% (w/v) of the compound of Chemical Formula 2 and one or more organic compound selected from saturated or unsaturated hydrocarbons, ethers (including cyclic ethers), esters, alcohols, amines (including cyclic amines), ketones, etc. as the balance may be prepared.

(23) The organic solvent is not limited as long as it can dissolve and does not react with the ferrocene-based compound, and is not specially limited as long as it can dilute the compound of Chemical Formula 2. Examples of the saturated or unsaturated hydrocarbon include aliphatic hydrocarbons such as pentane, hexane, heptane, octane, methene, ethene, propene, butene, pentene, hexene, heptene, octene, methyne, ethyne, propyne, butyne, pentyne, hexyne, heptyne, octyne, etc.; alicyclic hydrocarbons such as cyclopropane, cyclobutane, cyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, trimethylcyclohexane, ethylcyclohexane, diethylcyclohexane, decahydronaphthalene, bicycloheptane, tricyclodecane, hexahydroindenecyclohexane, cyclooctane, etc.; aromatic hydrocarbons such as benzene, toluene, xylene, mesitylene, etc.; or mixtures thereof, although not being limited thereto. Examples of the ethers (including cyclic ethers) include tetrahydrofuran, diethyl ether, methyl t-butyl ether or mixtures thereof, although not being limited thereto.

(24) Examples of the esters include methyl acetate, ethyl acetate, butyl acetate, butyl cellosolve acetate, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate or mixtures thereof, although not being limited thereto. Examples of the alcohols include methanol, ethanol, propanol, butanol or mixtures thereof, although not being limited thereto. Examples of the amides (including cyclic amides) include N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone or mixtures thereof, although not being limited thereto. Examples of the ketones include acetone, dimethyl ketone, methyl ethyl ketone, diethyl ketone or mixtures thereof, although not being limited thereto.

(25) The present disclosure also provides a hydrogen sulfide detection kit including a ferrocene-based compound which has high selectivity and superior sensitivity for sulfide ion.

(26) Specifically, the detection kit of the present disclosure includes a detection unit which is provided inside an airtight container and composed of paper or fabric to which a ferrocene compound is adsorbed; and a basic reagent which is stored inside or outside the airtight container and generates sulfide ion from hydrogen sulfide. The airtight container is prepared from a material which is stable against chemical substances and may include an opening/closing door or a detection material inlet.

(27) Ferrocene is an early known sandwich compound. It is a transition metal compound with the molecular formula (C.sub.5H.sub.5).sub.2Fe, having two organic rings bound on opposite sides of a central metal atom. Ferrocene is stable at room temperature and can be handled as general chemicals. For example, it has dangerousness comparable to that of acetone and is widely used commercially for digestives, catalysts for manufacturing of plastics such as PE, PP, etc., carbon nanotube materials, etc.

(28) In the hydrogen sulfide detection kit of the present disclosure, the ferrocene compound may be represented by Chemical Formula 1.

(29) ##STR00005##

(30) In the above chemical formula, each of R.sup.1 and R.sup.2 may be independently an organic compound selected from nitrile (CN), methyl ester (CO.sub.2Me) and ethyl ester (CO.sub.2Et), and R.sup.1 and R.sup.2 may be identical to or different from each other.

(31) The ferrocene-based compound of Chemical Formula 1 can be mass-produced economically and stably using a commercially available ferrocene compound and an organic compound as starting materials. As an example of the method for preparing the ferrocene-based compound, the ferrocene-based compound may be prepared through a reaction according to Reaction Scheme 1. After reacting a ferrocene starting material and an organic compound at an equimolar ratio in a solvent, the final compound is obtained by filtering the produced solid product and removing the solvent under reduced pressure.

(32) ##STR00006##

(33) A specific example of the produced final compound is shown in Chemical Formula 2, wherein both the organic compounds (R.sup.1, R.sup.2) are nitrile (CN).

(34) ##STR00007##

(35) The detection unit of the hydrogen sulfide detection kit may be prepared by dissolving a solid ferrocene-based compound in an organic solvent at room temperature. For example, a composition including 0.001-1.00% (w/v) of the compound of Chemical Formula 2 and one or more organic compound selected from saturated or unsaturated hydrocarbons, ethers (including cyclic ethers), esters, alcohols, amines (including cyclic amines), ketones, etc. as the balance may be adsorbed to paper or fabric, which is a material of the detection unit.

(36) The organic solvent is not limited as long as it can dissolve and does not react with the ferrocene-based compound, and is not specially limited as long as it can dilute the compound of Chemical Formula 2.

(37) The inventors of the present disclosure have identified that the ferrocene-based compound has selectivity for sulfide ion. As shown in FIG. 1, after preparing a 0.05% (w/v) solution by dissolving the compound of Chemical Formula 2 in an ethanol solvent, various aqueous anion solutions were added and color change was observed ({circle around (a)}: before addition of anion, {circle around (b)}): after addition of aqueous sodium sulfide (Na.sub.2S) solution, {circle around (c)}: after addition of aqueous sodium fluoride (NaF) solution, {circle around (d)}): after addition of aqueous potassium fluoride (KF) solution, {circle around (e)}: after addition of sodium chloride (NaCl) solution, {circle around (f)}: after addition of aqueous sodium iodide (NaI) solution).

(38) Whereas there was no color change of the chemical sensor solution before and after the addition of the aqueous sodium fluoride, potassium fluoride, sodium chloride or sodium iodide solution, color change occurred immediately (within several seconds) from violet to yellow when the aqueous sodium sulfide (Na.sub.2S) solution was added.

(39) In the present disclosure, a basic reagent which generates sulfide ion by reacting with hydrogen sulfide is used together with the ferrocene-based compound described above for detection of hydrogen sulfide. The reagent produces sulfide ion by instantly reacting with hydrogen sulfide in liquid or gas state, and color change occurs when the generated sulfide ion is exposed to the detection unit adsorbed to the ferrocene-based compound owing to a reaction that will be described below. As the basic reagent, any one that can generate sulfide ion by reacting with hydrogen sulfide may be used. For example, one or more selected from LiOH, NaOH, KOH, Mg(OH).sub.2, Ca(OH).sub.2, trimethylamine, triethylamine, pyridine and piperidine may be used in consideration of the chemical stability and safety of handling of the detection kit.

(40) In the present disclosure, the method for detecting hydrogen sulfide uses a hydrogen sulfide detection kit including a detection unit which is provided inside an airtight container and composed of paper or fabric to which a ferrocene compound is adsorbed, and a basic reagent which is stored inside or outside the airtight container and generates sulfide ion from hydrogen sulfide, wherein the basic reagent is coated or introduced into the detection unit, a part of the detection unit is drawn out of the airtight container by partially opening the airtight container and then is exposed to hydrogen sulfide solution or hydrogen sulfide gas, or hydrogen sulfide solution or hydrogen sulfide gas is introduced into the inlet, and the presence of hydrogen sulfide is judged by the color change of the detection unit from violet to yellow.

(41) The mechanism of hydrogen sulfide detection involves the following two-step reaction.

(42) First, in a sulfide ion generation step, sulfide ion is generated as hydrogen sulfide in gas or liquid state reacts with the basic reagent. For example, when sodium hydroxide is used as the reagent, sulfide ion is produced according to the following reaction.
H.sub.2S+2NaOH.fwdarw.S.sup.2−+2Na.sup.++2H.sub.2O  [Reaction Scheme 2]

(43) Next, the following reaction proceeds between the generated sulfide ion and the ferrocene compound.

(44) ##STR00008##

(45) Before the addition of sulfide ion, there exists a double bond between a ferrocenyl group and a dinitrile group of the ferrocene compound. But, when a sulfide ion (S.sup.2−) is introduced to the ferrocene compound, a single bond is formed between the ferrocenyl group and the dinitrile group. The color of the ferrocene compound is changed as the bonding structure is changed.

(46) A ferrocene-based compound is prepared for a kit for detecting hydrogen sulfide. After adding ferrocene aldehyde and malononitrile at an equimolar ratio as starting materials to an anhydrous ethanol solvent in a reactor, piperidine is added as a catalyst. Then, reaction was terminated after refluxing for 6 hours. After slowly lowering the reactor temperature to room temperature and filtering the produced solid product, the compound of Chemical Formula 2 (1,1-dicyanovinyl-2-ferrocene) was obtained by removing the solvent under reduced pressure. After adding 0.05 g of the prepared ferrocene compound to a 200-mL glass vial, 99.95 mL of ethanol was added. After closing the stopper of the glass vial and dissolving the compound by shaking the vial for 5 minutes, a 0.05% (w/v) detection solution was obtained. The prepared ferrocene compound solution exhibited violet color.

(47) The color change of the ferrocene detection solution in response to hydrogen sulfide gas and hydrogen sulfide solution was tested.

(48) FIGS. 7A and 7B show a detection test for hydrogen sulfide gas. After coating the ferrocene compound on cotton paper and coating a part of the detection unit with sodium hydroxide as a reagent, the kit was exposed to hydrogen sulfide gas. At first, the cotton paper exhibited violet color due to the ferrocene compound (FIG. 7A). When hydrogen sulfide gas collected in a glass bottle was supplied to the cotton paper through a supply tube, the portion coated with sodium hydroxide turned yellow immediately (FIG. 7B).

(49) FIGS. 8A and 8B show a detection test for hydrogen sulfide solution. When white cotton paper was twisted, soaked in an acetone solution containing the ferrocene compound and then kept at room temperature, the color of the cotton paper turned violet (FIG. 8A). When the violet cotton paper was dipped in hydrogen sulfide solution after soaking the end portion of the violet cotton paper in sodium hydroxide solution, the end portion of the violet cotton paper turned yellow immediately (FIG. 8B).

(50) FIG. 9 shows a detection test for sulfide ion solution. When thin paper was soaked in an acetone solution in which the ferrocene compound is dissolved and kept at room temperature, the paper turned violet. When the end portion of the violet paper was dipped in sulfide ion solution, the end portion of the violet paper turned pale yellow immediately.

(51) The hydrogen sulfide detection kit according to the present disclosure, which is equipped with the detection unit including the ferrocene compound, needs to have structure and function which allow easy carrying and provide stability for storage and use.

(52) FIG. 10 schematically shows a hydrogen sulfide detection kit 100 according to an exemplary embodiment of the present disclosure. A detection unit 130 is provided inside an airtight container 110 and an opening/closing door 112 is provided at one side of the container. The detection unit is seated on a moving piece 120 and may be exposed to outside as a guide handle 115 is moved linearly along a guide rail 114.

(53) The detection unit is composed of paper or fabric to which a ferrocene compound 132 is coated, adsorbed or deposited. It is kept inside the airtight container as being integrated and is exposed to outside during detection of hydrogen sulfide only, in order to prevent deformation or contamination of the ferrocene compound during storage. A basic reagent may be stored inside or outside the airtight container. In an exemplary embodiment, the reagent 134 is stored at one side of the detection unit inside the airtight container. For example, the reagent may be stored in a capsule-type container, and the capsule may be broken by pressing a capsule opener 135 so that the reagent may be dropped or coated onto the ferrocene compound of the detection unit. After the reagent is coated on the ferrocene compound, if the detection unit which is partially exposed out of the airtight container is exposed to a material to be detected, sulfide ion is generated from hydrogen sulfide via the two-step reaction described above when hydrogen sulfide is present. Then, color change owing to the reaction between the sulfide ion and the ferrocene compound can be observed directly in real.

(54) The reagent may be provided inside the airtight container being spaced apart from the detection unit, without being integrated to the detection unit, or may be kept on the outer surface of the airtight container, and may be coated onto or introduced to the detection unit prior to hydrogen sulfide detection. FIG. 11 schematically shows a hydrogen sulfide detection kit according to another exemplary embodiment of the present disclosure. It can be seen that the reagent 134 is provided at the side surface of the airtight container. The reagent may be introduced to the detection unit through an inlet 116 of the airtight container prior to hydrogen sulfide detection. Then, after supplying a material to be detected through the inlet, color change owing to the reaction with the reagent and the ferrocene compound of the detection unit may be observed. For this, a transparent window 111 for visual inspection may be provided on the surface of the airtight container, and the color change of the detection unit owing to the hydrogen sulfide solution or hydrogen sulfide gas introduced to the detection unit may be observed directly through the transparent window.

(55) According to the present disclosure, a hydrogen sulfide detection kit may be prepared economically by synthesizing a ferrocene-based compound via a simple method of reacting a commercially widely used starting material and diluting the same in an organic solvent. Since the chemical sensor of the present disclosure is capable of detecting sulfide ion in short time within several seconds and with high sensitivity, it can be used in various applications. Particularly, it can prevent the diffusion of hydrogen sulfide at an early stage on the site where spill accident has occurred by detecting sulfide ion at low concentration or high concentration in short time.

(56) Although the specific exemplary embodiments of the present disclosure have been described above, the present disclosure is not limited to the specific exemplary embodiments but may be modified, changed or improved in various forms within the scope of the technical idea of the present disclosure, specifically the scope defined by the appended claims.

EXAMPLE

(57) a) Preparation of Ferrocene-Based Compound

(58) First, a ferrocene-based compound represented by Chemical Formula 2 was prepared as a chemical sensor for detecting sulfide ion.

(59) After adding ferrocene aldehyde and malononitrile at an equimolar ratio as starting materials to an anhydrous ethanol solvent in a reactor, piperidine was added as a catalyst. Then, reaction was terminated after refluxing for 6 hours. After slowly lowering the reactor temperature to room temperature and filtering the produced solid product, the compound of Chemical Formula 2 (1,1-dicyanovinyl-2-ferrocene) was obtained by removing the solvent under reduced pressure.

(60) b) Chemical Sensor Solution for Detecting Sulfide Ion

(61) After adding 0.05 g of the prepared ferrocene compound to a 200-mL glass vial, 99.95 mL of ethanol was added. After closing the stopper of the glass vial and dissolving the compound by shaking the vial for 5 minutes, a 0.05% (w/v) detection solution was obtained. The prepared ferrocene compound solution exhibited violet color.

(62) c) Detection of Sulfide Ion Using Chemical Sensor Solution

(63) After adding 15.6 mg of sodium sulfide (Na.sub.2S) to a 100-mL flask, a 64 ppm aqueous sulfide ion solution was prepared by filling distilled water up to the mark. After transferring 10 mL of the solution to a 100-mL flask, a 6.4 ppm aqueous sulfide ion solution was prepared by filling distilled water up to the mark.

(64) After adding 3 mL of the prepared chemical sensor solution to a 10-mL glass vial and adding 3 mL of the 6.4 ppm aqueous sulfide ion solution, the stopper of the glass vial was closed and the vial was shaken with hands for 1 minute. The color of the solution was changed from violet to yellow.

(65) Test of Selectivity for Sulfide Ion

(66) FIG. 1 shows the color change of the 0.05% (w/v) solution prepared by dissolving the compound of Chemical Formula 2 in an ethanol solvent when added to various aqueous anion solutions ({circle around (a)}: before addition of anion, {circle around (b)}: after addition of aqueous sodium sulfide (Na.sub.2S) solution, {circle around (c)}: after addition of aqueous sodium fluoride (NaF) solution, {circle around (d)}: after addition of aqueous potassium fluoride (KF) solution, {circle around (e)}: after addition of sodium chloride (NaCl) solution, {circle around (f)}: after addition of aqueous sodium iodide (NaI) solution).

(67) Whereas there was no color change of the chemical sensor solution before and after the addition of the aqueous sodium fluoride, potassium fluoride, sodium chloride or sodium iodide solution, color change occurred immediately (within several seconds) from violet to yellow when the aqueous sodium sulfide (Na.sub.2S) solution was added. From this result, it can be seen that the chemical sensor of the present disclosure has selective responsivity to sulfide ion.

(68) Mechanism of Color Change in Response to Sulfide Ion

(69) The mechanism of color change occurring when the aqueous sulfide ion solution is added to the chemical sensor solution of the present disclosure can be explained as follows.

(70) FIG. 2 shows the UV-Vis spectra of the chemical sensor solution of the present disclosure before and after addition of sulfide ion. Absorption peaks were observed at 329.6 nm and 528.2 nm in the UV-Vis region before sulfide ion was added (left), and a single absorption peak was observed at 391.8 nm after sulfide ion was added (right).

(71) The two peaks observed before the addition of sulfide ion is attributed to the system wherein a π orbital function is conjugated by a double bond between the ferrocenyl group and the dinitrile group of the compound of Chemical Formula 2 as shown in FIG. 3A. The double bond between the ferrocenyl group and the dinitrile group lies on a plane as a sp.sup.2 hybrid orbital function, and two peaks are observed because free rotation is impossible (FIG. 3B).

(72) In contrast, as shown in FIG. 4A, when sulfide ion (S.sup.2−) is introduced to the double bond between the ferrocenyl group and the dinitrile group of the ferrocene-based compound of the present disclosure represented by Chemical Formula 2, a single bond is formed between the ferrocenyl group and the dinitrile group, and a single peak is observed since the sp.sup.3 hybrid orbital function of the single bond allows free rotation (FIG. 4B). In addition, the electrons produced as the sulfide ion (S.sup.2−) is introduced are strongly drawn by the two nitrile groups which are strong electron acceptors.

(73) Test of Sensitivity for Sulfide Ion

(74) In order to investigate the sensitivity for sulfide ion, sensitivity was tested by varying the concentration of sulfide ion.

(75) After adding aqueous sodium sulfide (Na.sub.2S) solutions of different concentrations to a 0.05% (w/v) solution of the chemical sensor of Chemical Formula 2 dissolved in an ethanol solvent, the change in the UV-Vis spectrum was observed. FIG. 5 shows the change in the UV-Vis spectrum depending on sulfide ion concentration.

(76) As the concentration of the aqueous sodium sulfide (Na.sub.2S) solution was increased from 1.28 ppm to 64 ppm, the intensities of the absorption peaks at 329.6 nm and 528.2 nm were decreased and, at the same time, a single absorption peak was observed at 391.8 nm. In particular, the 1.28 ppm aqueous sodium sulfide (Na.sub.2S) solution showed rapid decrease in the intensities of the absorption peaks at 329.6 nm and 528.2 nm even at low concentrations. This result shows that the chemical sensor of the present disclosure exhibits very high sensitivity even at a low concentration of sulfide ion.

(77) A chemical sensor using the ferrocene-based compound of the present disclosure and detection of sulfide ion using the same allow fast and accurate detection of sulfide ion with high sensitivity without requiring the complicated pretreatment of a sample containing sulfide ion, special chemical reaction conditions, expensive analytical instruments, etc.

(78) In particular, the presence of sulfide ion which is a source of hydrogen sulfide can be confirmed visually in real time through color change, and detection can be made in short time with high sensitivity without being affected by environmental factors such as temperature and humidity. Accordingly, sulfide ion can be detected in real time at accident site, and the present disclosure can be actively utilized for detection of aqueous hydrogen sulfide solution on site.

(79) Although the present disclosure has been described with specific exemplary embodiments, the present disclosure is not limited to the specific exemplary embodiments and they may be modified, changed or improved variously within the technical scope presented in the present disclosure, specifically the scope defined in the appended claims.

DETAILED DESCRIPTION OF MAIN ELEMENTS

(80) TABLE-US-00001 100: detection kit 110: airtight container 111: transparent window 112: opening/closing door 114: guide rail 115: guide handle 116: inlet 120: detection unit moving piece 130: detection unit 132: ferrocene compound 134: reagent 135: capsule opener