Paper-based detection method for detecting ethanethiol

Abstract

The invention discloses a paper-based detection method for detecting ethanethiol, which comprises the following specific steps: firstly, by taking silver nitrate as a silver source, oleylamine as a modifier, xylene as an organic solvent and ascorbic acid as a reducing agent, preparing oleylamine modified hydrophobic silver nanoparticles through an organic solvent chemical reduction method; a paper-based colorimetric sensor array with silver nanoparticle sensing element points in a 1 * 5 mode is constructed on a hydrophobic PVDF paper base. And finally, applying the paper-based sensor to qualitative and quantitative analysis detection of ethanethiol gas. The lowest detection limit of the obtained methyl mercaptan is 20.9 ppb. The paper-based sensor has excellent specific recognition capability on ethanethiol, and is high in sensitivity and high in response speed. The silver nanoparticle paper-based colorimetric sensor array provided by the invention has the characteristics of low cost, high sensitivity and strong selectivity, can quickly and effectively detect the content of ethanethiol, and reduces the harm of ethanethiol to human and environment.

Description

Technical Field

[0001] The present application relates to a paper-based detection method for detecting ethyl mercaptan, belonging to the technical field of gas detection. Background Art

[0002] Ethyl mercaptan (C2H5SH) is a foul-smelling organic compound known for its strong, persistent and pungent garlic smell. It has high toxicity, low vapor pressure and extremely low odor threshold. When the air contains only one part per fifty billion of ethyl mercaptan (0.00019 mg / L), its odor can be smelled. When inhaled in large quantities by the human body, it can cause breathing difficulties, lowered blood pressure, and symptoms such as vomiting and sore throat. Ethyl mercaptan is an important pesticide intermediate used in the synthesis of organophosphorus insecticides such as phorate, disulfothion, isopropylphos, demeton, methyl demeton and herbicide sethoxydim. In addition, it can also be used as a reagent and gas odorizer, liquid fuel additive, and in pharmaceutical synthesis. Therefore, it is crucial to develop a technology that can quickly and effectively detect ethyl mercaptan gas to ensure the air quality of human working environments.

[0003] Traditional methods for detecting ethanethiol mainly include gas chromatography-mass spectrometry (GC-MS), infrared absorption spectroscopy, quartz crystal microbalance sensor, carbon adsorption method, electrochemistry, etc. However, in practical applications, these methods have some inevitable disadvantages, such as high cost, complex operation, long detection time, low sensitivity, complex sample pretreatment, and inability to monitor in real time, especially in emergency situations.

[0004] In contrast, chemical sensors have the outstanding advantages of low cost, strong selectivity, high sensitivity and good stability. Their detection principle is to identify the chemical reaction between the element and the analyte, rather than the weak, highly non-specific physical interaction (such as physical adsorption causing changes in the mass, volume or conductivity of the material), so they are more specific.

[0005] Sensor recognition elements are the core of chemical sensors. Silver nanoparticles have properties that are different from conventional materials, such as optical, electrical, magnetic, and thermal properties, due to their surface effects, small size effects, quantum size effects, macroscopic quantum tunneling effects, and dielectric confinement effects. In addition, silver nanoparticles have a larger extinction coefficient and a narrower surface plasma resonance band, and therefore have better colorimetric properties, higher sensitivity, and higher reactivity. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention is based on the mechanism of the interaction between -NH2 groups and -SH groups to form Lewis acid-base compounds. Ethyl mercaptan reacts chemically with the surface group -NH2 of silver nanoparticles, causing the surface modifier to fall off and inducing the agglomeration of nanoparticles, thereby generating a colorimetric response. A paper-based sensor for visual detection of ethyl mercaptan and a preparation method thereof are provided.

[0007] The invention adopts an organic solvent chemical reduction method, uses silver nitrate as a silver source and oleylamine as a modifier to prepare hydrophobic silver nanoparticles. Using PVDF hydrophobic paper as a carrier, a paper-based sensor for visual detection of ethanethiol and a preparation method thereof are provided.

[0008] According to one aspect of the present application, a paper-based detection method for detecting ethanethiol is provided, and the preparation method comprises the following steps:

[0009] (1) stirring, filtering, and centrifuging a mixture containing silver nitrate, oleylamine, a reducing agent, and an organic solvent to obtain oleylamine-modified hydrophobic silver nanoparticles;

[0010] (2) diluting the same oleylamine-modified hydrophobic silver nanoparticles with different volumes of xylene to obtain oleylamine-modified hydrophobic silver nanoparticles with different concentrations;

[0011] (3) taking the same volume of oleylamine-modified hydrophobic silver nanoparticles with different concentrations and immobilizing them on a paper substrate, and printing them to obtain a silver nanoparticle paper-based colorimetric sensor with multiple sensing origins;

[0012] (4) adding different concentrations of ethyl mercaptan gas to a silver nanoparticle paper substrate having multiple sensing origins, observing the color change, and obtaining an ethyl mercaptan gas standard colorimetric card;

[0013] (5) Add unknown concentration of ethyl mercaptan gas to a silver nanoparticle paper substrate with multiple sensitive points, observe the color change, and compare it with the standard ethyl mercaptan gas colorimetric card to obtain the concentration of the unknown concentration of ethyl mercaptan gas.

[0014] Optionally, in step (1), the concentration of silver nitrate is 0.10-0.13M.

[0015] Optionally, in step (1), the concentration of silver nitrate is selected from any value among 0.10M, 0.11M, 0.12M, 0.13M or a range between any two of the above values.

[0016] Optionally, the concentration of oleylamine is 0.75-0.95M.

[0017] Optionally, the concentration of oleylamine is selected from any value among 0.75M, 0.80M, 0.85M, 0.90M, 0.95M or a range between any two of the above values.

[0018] Optionally, the reducing agent is selected from at least one of ascorbic acid, glucose, and NaBH4.

[0019] Optionally, the organic solvent is selected from benzene, toluene, xylene and n-hexane.

[0020] Optionally, in step (1), the concentration of the reducing agent is 0.12-0.18M.

[0021] Optionally, in step (1), the concentration of the reducing agent is selected from any value among 0.12M, 0.13M, 0.14M, 0.15M, 0.16M, 0.17M, 0.18M or a range between any two of the above.

[0022] Optionally, in step (1), the centrifugal speed is 5000-6000 r / min, and the centrifugal time is 5-8 min.

[0023] Optionally, in step (2), the amount of the same oleylamine-modified hydrophobic silver nanoparticles used is 500-600 μL.

[0024] Optionally, the silver nanoparticle paper-based colorimetric sensor with multiple sensing origins has a detection limit of 20.9 to 22.00 ppb for ethyl mercaptan.

[0025] Optionally, in step (3), the diameter of the sensing origin in the silver nanoparticle paper-based colorimetric sensor having multiple sensing origins is 2.8 to 3.5 mm.

[0026] Optionally, in step (3), the dosage of the same volume is 1 to 1.5 μL.

[0027] Optionally, the paper base is selected from at least one of PVDF, whatman No. 1 filter paper, and whatman No. 2 filter paper.

[0028] Optionally, in step (3), the silver nanoparticle paper-based colorimetric sensor with multiple sensing origins has an anti-interference range of 10% to 90% to humidity.

[0029] Optionally, in step (4), the ethanethiol gas standard colorimetric card is stored in an inactive atmosphere.

[0030] Optionally, the inert atmosphere is selected from at least one of nitrogen, helium and argon.

[0031] As a specific implementation, the present application is implemented through the following technical solutions:

[0032] A method for preparing a paper-based sensor for visually detecting ethanethiol comprises the following steps:

[0033] (1) Preparation of hydrophobic silver nanoparticles:

[0034] Silver nitrate and oleylamine were dissolved in 25 ml of organic solvent, and the mixed solution was ultrasonically treated for 30 min to dissolve the silver nitrate. Ascorbic acid was used as a reducing agent and added to the mixed solution. The solution was magnetically stirred at room temperature for 3 h, and the solution changed from colorless to brownish yellow until it stopped changing color, indicating that the reduction of the silver nanoparticles was complete. The generated organic nanosilver was filtered with filter paper, and the filtrate was centrifuged to collect the supernatant to obtain hydrophobic silver nanoparticles modified with oleylamine.

[0035] (2) Construction of Paper-Based Colorimetric Sensor Array Device

[0036] The silver nanoparticles prepared in step (1) were used to extract the same volume of nanosilver stock solution, which was diluted to 5 concentrations using different volumes of xylene, and then a certain volume of nanosilver solution was manually transferred by a pipette and immobilized on a PVDF paper substrate to print a silver nanoparticle paper-based colorimetric sensor array with 5 sensing elements. The sensor was placed in a screw-mouth glass bottle, N2 was introduced to isolate oxygen, and stored at room temperature for later use.

[0037] (3) Preparation of ethanethiol standard colorimetric card and quantitative detection model M

[0038] The paper-based sensor was exposed to different concentrations of ethyl mercaptan gas for 10 minutes. The sensor's response to different concentrations of ethyl mercaptan gas produced different color response fingerprints. Different color response fingerprints were matched with different concentrations of ethyl mercaptan gas, and arranged in order from small to large ethyl mercaptan concentrations to establish a standard colorimetric test paper card for detecting ethyl mercaptan gas. The ΔRGB values ​​of the images before and after the response were extracted to establish a model M for quantitative detection of ethyl mercaptan.

[0039] (4) Specific recognition and detection of ethyl mercaptan gas by paper-based sensors.

[0040] The specific identification and detection of methyl mercaptan gas by paper-based sensors includes: the influence of common potential interfering gases on ethyl mercaptan gas detection; the influence of environmental humidity.

[0041] Optionally, in step (2), the same volume of stock solution is extracted as 500ul, and different volumes of xylene are 0, 2, 4, 8, and 12ml respectively; the volume transferred by the pipette is 1-1.5ul, the diameter of the sensing origin is 2.8-3.5mm, N2 is introduced into the paper-based sensor for 1h, and then placed at room temperature for 12h.

[0042] Optionally, in step (3), the concentrations of ethanethiol gas are 0.1 ppm, 0.5 ppm, 1.0 ppm, 1.5 ppm, 2.0 ppm, 2.5 ppm, 3.0 ppm, and 3.5 ppm, respectively.

[0043] Optionally, in step (4), the interfering gas is: ethylenediamine, ammonia, acetic acid, carbon disulfide, dimethyl sulfide, formaldehyde, ethanol, styrene; and the ambient humidity is 10% to 90%.

[0044] In the present application, a method for preparing a paper-based sensor for visually detecting ethyl mercaptan is provided, and the specific steps are as follows: first, using silver nitrate as a silver source, oleylamine as a modifier, xylene as an organic solvent, and ascorbic acid as a reducing agent, hydrophobic silver nanoparticles modified with oleylamine are prepared by an organic solvent chemical reduction method. A paper-based colorimetric sensor array with a silver nanoparticle sensing element point in a 1x 5 pattern is constructed on a hydrophobic PVDF paper substrate. Finally, the paper-based sensor is used for qualitative and quantitative analysis and detection of ethyl mercaptan gas. The minimum detection limit of methyl mercaptan is obtained to be 20.9ppb. The paper-based sensor has excellent specific recognition ability for ethyl mercaptan, high sensitivity, and fast response speed. The silver nanoparticle paper-based colorimetric sensor array provided by the present invention has the characteristics of low cost, high sensitivity, and strong selectivity, and can quickly and effectively detect the content of ethyl mercaptan, reducing its harm to humans and the environment.

[0045] The beneficial effects of this application include:

[0046] 1) The silver nanoparticle paper-based colorimetric sensor array provided in the present application has an obvious specific recognition response to the detection of ethyl mercaptan gas and can be used for the detection of ethyl mercaptan gas in complex environments.

[0047] 2) The present application uses a hydrophobic paper substrate as a substrate and an array to improve the detection efficiency of the sensor for ethanethiol. At the same time, a method for visual detection of analytes is provided by a silver nanoparticle colorimetric method. A paper-based sensor for visual detection of ethanethiol and a preparation method thereof are low in cost, simple to operate, portable, and have broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is a TEM image of the morphology of oleylamine-modified silver nanoparticles prepared in Example 1 of the present application, with a scale of 20 nm.

[0049] Figure 2 This is the silver nanoparticle paper-based colorimetric sensor array prepared in Example 1 of the present application.

[0050] Figure 3 This is the standard colorimetric test paper card for detecting ethyl mercaptan prepared in Example 1 of the present application.

[0051] Figure 4 This is a diagram of the model M-linear fitting equation for quantitative detection of ethyl mercaptan by the paper-based sensor prepared in Example 1 of the present application.

[0052] Figure 5 This is the effect of the interfering gas prepared in Example 2 of the present application on the detection of ethyl mercaptan gas.

[0053] Figure 6 This is the effect of environmental humidity on the detection of ethyl mercaptan gas by the paper-based sensor prepared in Example 3 of the present application. DETAILED DESCRIPTION

[0054] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0055] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0056] Example 1

[0057] A paper-based sensor for visual detection of ethanethiol and a preparation method thereof. The invention comprises the following steps:

[0058] (1) Preparation of hydrophobic silver nanoparticles

[0059] Dissolve 0.12M silver nitrate and 0.86M oleylamine in 25ml of organic solvent, and treat the mixed solution ultrasonically for 30 minutes to dissolve the silver nitrate. Use 0.16M ascorbic acid as a reducing agent and add it to the mixed solution. Stir magnetically at room temperature for 3 hours. The solution changes from colorless to brownish yellow until it stops changing color, indicating that the reduction of the silver nanoparticles is complete. Filter the generated organic nanosilver with filter paper, and then centrifuge the filtrate at 5000-6000r / min for 5min. Collect the supernatant to obtain oleylamine-modified hydrophobic silver nanoparticles. Figure 1 The TEM shown in the figure shows that the prepared silver nanoparticles are spherical and have good monodispersity.

[0060] (2) Construction of Paper-Based Colorimetric Sensor Array Device

[0061] The silver nanoparticles prepared in step 1 were extracted with the same volume of 500ul of nanosilver stock solution, and diluted to 5 concentrations with 0, 2, 4, 8, and 12ml of xylene, respectively. Then, 1ul of the nanosilver solution was manually transferred by a pipette and immobilized on a PVDF paper substrate to print a silver nanoparticle paper-based colorimetric sensor array with 5 sensing elements, as shown in FIG. Figure 2 As shown, the diameter of the sensing element is 2.8-3.5 mm. The paper-based sensor was placed in a screw-mouth glass bottle, N2 was introduced for 1 hour, and then placed at room temperature for 12 hours.

[0062] (3) Preparation of ethanethiol standard colorimetric card and quantitative detection model M

[0063] The paper-based sensor was exposed to 0.1ppm, 0.5ppm, 1.0ppm, 1.5ppm, 2.0ppm, 2.5ppm, 3.0ppm, and 3.5ppm ethanethiol gas for 10 minutes. The sensor's response to different concentrations of ethanethiol gas will produce different color response fingerprints. Different color response fingerprints are matched to different concentrations of ethanethiol gas, and arranged in order from small to large ethanethiol concentrations to establish a standard colorimetric test paper card for detecting ethanethiol gas, such as Figure 3 A flatbed scanner was used to extract the spectrum of the sensor before and after the response, and Photoshop was used to extract the ΔRGB value of the image. ΔR is the difference in red color values ​​before and after the response, ΔG is the difference in green color values ​​before and after the response, and ΔB is the difference in blue color values ​​before and after the response.

[0064] The ED value was plotted as the ordinate and the ethyl mercaptan concentration was plotted as the abscissa, and the model M for quantitative detection of ethyl mercaptan was established - the linear fitting equation y = 40.12x + 80.19 was obtained. Figure 4 As shown, x is the concentration of ethanethiol. The LOD of the gas is calculated by the formula LOD = 3δ / K. K is the slope of the fitting curve, and δ = 0.28 is the relative standard deviation of the blank group. Figure 4 It can be seen that the minimum detection limit of ethyl mercaptan is 20.9 ppb.

[0065] Example 2

[0066] The influence of interfering gases on ethyl mercaptan gas detection

[0067] The detection of ethyl mercaptan gas by interfering gases was carried out in an 18L closed gas box. A micro-injector was used to transfer ethyl mercaptan stock solution and drop it on the heating plate in the gas box to make the gas concentration in the gas box 0.5ppm. After standing for 10 minutes, the paper-based sensor was exposed to the gas box to respond to ethyl mercaptan gas and detect for 10 minutes. The same steps were used to detect ethylenediamine, ammonia, acetic acid, carbon disulfide, dimethyl sulfide, formaldehyde, ethanol, and styrene at a concentration of 5ppm using paper-based sensors for 10 minutes. Finally, a flatbed scanner was used to collect spectra of the sensor before and after its response to the above 9 gases, and the colorimetric response fingerprint was extracted using the ChemEye older software. By Figure 5 It can be seen that the paper-based sensor has an obvious colorimetric response to ethyl mercaptan, but has no response to other interfering gases, even when the concentration is greater than 10 times (5 ppm), indicating that the sensor has excellent selectivity in responding to ethyl mercaptan.

[0068] Example 3

[0069] Effect of environmental humidity on the detection of methyl mercaptan gas by paper-based sensor

[0070] The humidity of the gas measuring box was adjusted by a humidifier to 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90% respectively. The paper-based colorimetric sensor array was then placed in the above different humidity conditions and allowed to stand for 10 minutes. A flatbed scanner was used to collect the spectra of the sensor before and after standing at the above 9 humidity conditions. 0.5 ppm ethyl mercaptan gas was added to the gas measuring boxes with different relative humidity conditions, and the paper-based colorimetric sensor array was exposed to the above different humidity conditions containing ethyl mercaptan gas and tested for 10 minutes. A flatbed scanner was used to collect the spectra before and after the sensor response. The ΔRGB value of the spectrum was extracted through photoshop, and the formula was used. ΔR is the difference in red color value before and after the response, ΔG is the difference in green color value before and after the response, and ΔB is the difference in blue color value before and after the response;

[0071] The sensor color change value ED is calculated. Figure 6 It can be seen that humidity has little effect on the sensor itself. As humidity increases, the effect on the sensor's detection of ethyl mercaptan does not change much, indicating that the paper-based sensor has excellent moisture resistance.

[0072] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A paper-based detection method for detecting ethanethiol, characterized in that, The preparation method comprises the following steps: (1) stirring, filtering, and centrifuging a mixture containing silver nitrate, oleylamine, a reducing agent, and an organic solvent to obtain oleylamine-modified hydrophobic silver nanoparticles; (2) diluting the same oleylamine-modified hydrophobic silver nanoparticles with different volumes of xylene to obtain oleylamine-modified hydrophobic silver nanoparticles with different concentrations; (3) taking the same volume of oleylamine-modified hydrophobic silver nanoparticles with different concentrations and immobilizing them on a paper substrate, and printing them to obtain a silver nanoparticle paper-based colorimetric sensor with multiple sensing origins; (4) adding different concentrations of ethyl mercaptan gas to a silver nanoparticle paper substrate having multiple sensing origins, observing the color change, and obtaining an ethyl mercaptan gas standard colorimetric card; (5) Add unknown concentration of ethyl mercaptan gas to a silver nanoparticle paper substrate with multiple sensitive points, observe the color change, and compare it with the standard ethyl mercaptan gas colorimetric card to obtain the concentration of the unknown concentration of ethyl mercaptan gas.

2. The paper-based detection method according to claim 1, characterized in that: In the step (1), the concentration of the silver nitrate is 0.10 to 0.13 M; Preferably, the concentration of oleylamine is 0.75 to 0.95 M; Preferably, the reducing agent is selected from at least one of ascorbic acid, glucose and NaBH4; Preferably, the organic solvent is selected from benzene, toluene, xylene and n-hexane.

3. The paper-based detection method according to claim 1, characterized in that: In the step (1), the concentration of the reducing agent is 0.12-0.18M.

4. The paper-based detection method according to claim 1, characterized in that: In the step (1), the centrifugal speed is 5000-6000 r / min, and the centrifugal time is 5-8 min.

5. The paper-based detection method according to claim 1, characterized in that: In the step (2), the amount of the same oleylamine-modified hydrophobic silver nanoparticles used is 500-600 μL.

6. The paper-based detection method according to claim 1, characterized in that: The silver nanoparticle paper-based colorimetric sensor with multiple sensing origins has a detection limit of 20.9-22.00 ppb for ethyl mercaptan.

7. The paper-based detection method according to claim 1, characterized in that: In the step (3), the diameter of the sensing origin in the silver nanoparticle paper-based colorimetric sensor having multiple sensing origins is 2.8 to 3.5 mm.

8. The paper-based detection method according to claim 1, characterized in that: In the step (3), the dosage of the same volume is 1 to 1.5 μL; The paper base is selected from at least one of PVDF, whatman No. 1 filter paper and whatman No. 2 filter paper.

9. The paper-based detection method according to claim 1, characterized in that: In the step (3), the silver nanoparticle paper-based colorimetric sensor with multiple sensing origins has an anti-interference range of 10% to 90% to humidity.

10. The paper-based detection method according to claim 1, characterized in that: In the step (4), the ethanethiol gas standard colorimetric card is stored in an inert atmosphere; Preferably, the inert atmosphere is selected from at least one of nitrogen, helium and argon.

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