Sensitive material of morphine gas sensor, gas sensor, preparation method and application

Abstract

The invention discloses a morphine gas sensor sensitive material, a gas sensor, a preparation method and an application, and belongs to the technical field of gas sensor materials and drug detection, the sensitive material has a porous foam network structure formed by interconnection assembly of 3d10 electron zinc oxide (ZnO) nanoparticles, the gas sensor is a tubular structure gas sensor, and the gas sensor has a porous foam network structure. A sensitive material is prepared by adopting a PVP chelation precipitation-chemical blow molding calcination method, and the sensitive material is coated outside a ceramic tube of a tubular structure gas sensor, and is used for detecting morphine in methanol. The gas sensor prepared from the morphine gas sensor sensitive material has the advantages of detection sensitivity, simplicity in operation, high applicability and low preparation cost, and the preparation method has the advantage of simplicity in operation.

Description

Technical Field

[0001] The present invention belongs to the technical field of gas sensor materials and drug detection, and specifically relates to a morphine gas sensor sensitive material, a gas sensor, a preparation method and an application. Background Art

[0002] Morphine has extremely potent analgesic and sedative effects and is commonly used as an anesthetic in clinical surgery. It is the most widely used powerful analgesic worldwide, and excessive use can be highly addictive. According to my country's Narcotics Control Law and Criminal Law, addictive narcotics and psychotropic substances such as morphine are defined as drugs. The United Nations Commission on Narcotic Drugs also lists morphine as one of the six major drugs. Morphine use can cause pathological effects on the central nervous system, respiratory system, cardiovascular system, and digestive system. Overdose through inhalation or injection can cause bradycardia, hallucinations, and even death. Furthermore, morphine's highly addictive nature can lead to severe dependence, resulting in significant physical and mental damage to long-term users. Driven by profit, criminals are currently exploiting morphine's solubility in alcoholic solvents to attempt to evade customs inspections by concealing the drug in methanol solutions disguised as alcoholic beverages, posing a significant challenge to drug control efforts. Therefore, developing a convenient and accurate detection method for quickly detecting hidden morphine drugs is of great significance in combating drug trafficking, smuggling and other crimes.

[0003] Commonly used drug detection methods based on gas chromatography-mass spectrometry (GC-MS) (publication number: CN116754679A) and liquid chromatography-mass spectrometry (LC-MS) (publication number: CN113267556A) are limited to laboratory applications due to high technical requirements and high costs. LFCA test strips based on lateral flow chromatography (LFCA) (publication number: CN119178875A) are mainly used for the detection of known drugs. However, they face problems such as slow test results, susceptibility to impurity interference, and inability to accurately quantify, which are not conducive to the actual use of rapid screening tests. The current method of efficiently finding hidden drugs is still the sniffing of drug detection dogs. However, with the diversification and increasing concealment of drug trafficking and smuggling methods, it is difficult for drug detection dogs to effectively identify drugs hidden in alcohol solutions with pungent odors, greatly reducing the efficiency of case detection. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, the present invention aims to provide a morphine gas sensor sensitive material, a gas sensor, a preparation method and an application thereof, wherein the sensitive material has 3D 10The porous foam network structure formed by interconnected assembly of electronic zinc oxide (ZnO) nanoparticles is used to detect morphine in methanol, which improves the sensitivity of the gas sensor in detecting morphine drugs in methanol. The gas sensor prepared using this sensitive material has low raw material cost, is easy to operate, and its preparation method is simple.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A morphine gas sensor sensitive material with 3D 10 A porous foam-like network structure formed by interconnected assembly of electronic zinc oxide (ZnO) nanoparticles.

[0007] The raw materials for preparing a morphine gas sensor sensitive material include: zinc nitrate hexahydrate (Zn(NO3)2·6H2O), anhydrous ethanol, polyvinylpyrrolidone (PVP) and ammonia water (NH3·H2O), with a solid-liquid ratio of (0.1-20) g:15 mL: (0.1-10) g: (1-10) mL, and the average molecular weight of polyvinylpyrrolidone (PVP) is 8000-700000.

[0008] Application of morphine gas sensor sensitive materials, morphine gas sensor sensitive materials are used in the detection of morphine in methanol.

[0009] A gas sensor is a tubular gas sensor coated with a morphine gas sensor sensitive material.

[0010] A method for preparing a gas sensor comprises the following steps:

[0011] Step 1, preparing a morphine gas sensor sensitive material by using a PVP chelating precipitation-chemical blowing calcination method;

[0012] Step 2: Prepare a tubular structure gas sensor based on the sensitive material prepared in step 1.

[0013] The step 1 specifically includes the following steps:

[0014] Step 1.1, disperse zinc nitrate hexahydrate (Zn(NO3)2·6H2O) in anhydrous ethanol solution at a solid-liquid ratio of (0.1-20) g:15 mL, and stir at 20-40°C until fully dissolved;

[0015] Step 1.2, dispersing polyvinyl pyrrolidone (PVP) in the solution prepared in step 1.1, wherein the average molecular weight of polyvinyl pyrrolidone (PVP) is 8000-700000, the solid-liquid ratio is (0.1-10) g:15 mL, and stirring at 20-40° C. until fully dissolved;

[0016] Step 1.3, add 1-10 mL of aqueous ammonia (NH3·H2O) dropwise to the solution prepared in step 1.2 to form a white flocculant zinc hydroxide (Zn(OH)2) precipitate at the bottom of the solution until the added aqueous ammonia (NH3·H2O) makes the solution clear;

[0017] Step 1.4, precipitating the white flocculant zinc hydroxide (Zn(OH)2) produced in step 1.3 by air blowing in an oven at 25-80°C for 0.5-24h;

[0018] Step 1.5: blow-molded product in step 1.4 in a muffle furnace at 1-5°C / min. -1 The heating rate is increased to 300-700°C and the mixture is kept warm and calcined for 1-3 hours to finally prepare a morphine gas sensor sensitive material.

[0019] The step 2 specifically includes the following steps:

[0020] Step 2.1: Mix the morphine gas sensor sensitive material with deionized water to form a uniform paste with a solid-liquid ratio of (0.1-1.0) g:5 mL. Then, coat the paste on a ceramic tube 1 to form a gas-sensitive material film 2 with a thickness of 5-50 μm. A pair of gold electrodes 3 are disposed between the ceramic tube 1 and the gas-sensitive material film 2. Each gold electrode 3 is connected to two platinum leads 4.

[0021] Step 2.2, after the gas-sensitive material film 2 is completely dried, the ceramic tube is calcined in a muffle furnace at 300-500° C. at a heating rate of 1-5° C. / min for 0.5-3 h to firmly fix it;

[0022] Step 2.3: Pass a spiral nickel-chromium heating coil 5, which is used to control the operating temperature of the sensor, through the interior of the ceramic tube 1. Connect four platinum leads 4 and both ends of the nickel-chromium heating coil 5 to the hexagonal base 6 to prepare a tubular gas sensor.

[0023] Step 2.4: age the tubular structure gas sensor obtained in step 2.3 in an air environment at 200-400° C. for 3-7 days to stabilize its structure.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The 3D 10 The porous foam network structure sensitive material composed of interconnected electronic zinc oxide (ZnO) nanoparticles improves the sensitivity of gas sensors in detecting morphine drugs in methanol.

[0026] 2. The present invention adopts PVP chelating precipitation-chemical blowing calcination method to prepare gas sensor sensitive materials. The synthetic raw materials used are low in cost and the preparation method is simple.

[0027] 3. The present invention adopts a coating process to prepare a tubular gas sensor, which has simple steps and is easy to operate.

[0028] 4. The present invention uses a gas sensor made of morphine gas sensor sensitive materials to detect whether methanol contains morphine drugs by using the change in the resistance value of the gas sensor. The detection results are intuitive and do not require professional personnel to perform data analysis and processing. It is convenient and easy to use and has universal applicability.

[0029] 5. The present invention adopts 3D 10 A gas sensor is prepared by using a porous foam network structure sensitive material composed of interconnected zinc oxide (ZnO) nanoparticles. Morphine drugs are detected by the gas sensor. The detection results are fast and sensitive, which can meet the needs of key places such as customs for immediate detection of morphine drugs hidden in irritating methanol solutions.

[0030] In summary, the sensor of the present invention has the advantages of being sensitive, easy to operate, highly applicable and low cost, and the preparation method thereof has the advantage of being easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the SEM image of the prepared ZnO-N-1 sensitive material provided in Example 1 of the present invention.

[0032] Figure 2 This is an SEM image of the prepared ZnO-N-2 sensitive material provided in Example 2 of the present invention.

[0033] Figure 3 This is the SEM image of the prepared ZnO-N-3 sensitive material provided in Example 3 of the present invention.

[0034] Figure 4 This is the SEM image of the prepared ZnO-N-4 sensitive material provided in Example 4 of the present invention.

[0035] Figure 5 These are the XRD patterns of the ZnO-N-1, ZnO-N-2, ZnO-N-3, and ZnO-N-4 sensitive materials prepared in Examples 1 to 4 of the present invention.

[0036] Figure 6 Schematic diagram of the testing process mechanism for laboratory detection of morphine drugs in methanol provided in Examples 1 to 4 of the present invention.

[0037] Figure 7The test sensitivity values ​​of the ZnO-N-1, ZnO-N-2, ZnO-N-3, and ZnO-N-4 sensors provided in Examples 1 to 4 of the present invention to a 100 ppm morphine standard solution in a methanol background at different operating temperatures.

[0038] FIG8( a ) is a curve diagram showing the sensitivity change of the sensor ZnO-N-2 provided in Example 2 of the present invention to morphine standard solutions of different concentrations in a methanol background at the optimal working temperature (250° C.).

[0039] FIG8( b ) is a fitting curve diagram of the sensitivity change of the sensor ZnO-N-2 provided in Example 2 of the present invention to morphine standard solutions of different concentrations in a methanol background at the optimal working temperature (250° C.).

[0040] Figure 9 This is a bar graph of the detection response values ​​of the sensor ZnO-N-2 provided in Example 2 of the present invention to different types of gases at 100 ppm in a methanol background at the optimal operating temperature (250°C).

[0041] Figure 10 This is a long-term stability test curve of the sensor ZnO-N-2 provided in Example 2 of the present invention at the optimal working temperature (250° C.) for 100 ppm morphine standard solution in a methanol background within 30 days.

[0042] Figure 11 This is a schematic structural diagram of the morphine gas sensor of the present invention.

[0043] In the figure, 1 is a ceramic tube, 2 is a sensitive material film, 3 is a gold electrode, 4 is a platinum lead, 5 is a nickel-chromium heating coil, and 6 is a hexagonal base.

[0044] Figure 12 Statistical analysis of the trial test results of the ZnO-N-2 sensor provided in Example 2 of the present invention at the Guangdong Customs. DETAILED DESCRIPTION

[0045] The present invention will be described in detail below with reference to the accompanying drawings.

[0046] Example 1

[0047] like Figure 1 As shown, a morphine gas sensor sensitive material, its structure is 3D 10 The porous foam-like network structure assembled by interconnected electronic zinc oxide (ZnO) nanoparticles is defined as ZnO-N-1.

[0048] A morphine gas sensor sensitive material is prepared from raw materials including zinc nitrate hexahydrate (Zn(NO3)2·6H2O), anhydrous ethanol, polyvinylpyrrolidone (PVP) and ammonia water (NH3·H2O), with a solid-liquid ratio of 0.1 g:15 mL:0.1 g:1 mL. The average molecular weight of the polyvinylpyrrolidone (PVP) is 700,000.

[0049] The morphine gas sensor sensitive material is used for detecting morphine in methanol.

[0050] A gas sensor is a tubular gas sensor coated with the morphine gas sensor sensitive material.

[0051] The method for preparing the gas sensor comprises the following steps:

[0052] Step 1, preparing a morphine gas sensor sensitive material by using a PVP chelating precipitation-chemical blowing calcination method;

[0053] Step 1.1, disperse zinc nitrate hexahydrate (Zn(NO3)2·6H2O) in anhydrous ethanol solution at a solid-liquid ratio of 0.1 g:15 mL and stir at 20°C until fully dissolved;

[0054] Step 1.2, dispersing polyvinyl pyrrolidone (PVP) in the solution prepared in step 1.1, wherein the average molecular weight of polyvinyl pyrrolidone (PVP) is 700,000 and the solid-liquid ratio is 0.1 g:15 mL, and stirring at 20°C until fully dissolved;

[0055] Step 1.3: Add 1 mL of aqueous ammonia (NH3·H2O) dropwise to the solution prepared in step 1.2 to form a white flocculant, zinc hydroxide (Zn(OH)2), precipitate at the bottom of the solution until the added aqueous ammonia (NH3·H2O) makes the solution clear.

[0056] Step 1.4, the white flocculant zinc hydroxide (Zn(OH)2) produced in step 1.3 was precipitated by air blowing in an oven at 25°C for 24 h;

[0057] Step 1.5, heating the blow-molded product in step 1.4 to 300° C. at a heating rate of 1° C. / min in a muffle furnace, and calcining the mixture for 3 hours to obtain a morphine gas sensor sensitive material.

[0058] Step 2, preparing a tubular structure gas sensor based on the sensitive material prepared in step 1;

[0059] Step 2.1: Mix the morphine gas sensor sensitive material with deionized water to form a uniform paste with a solid-liquid ratio of 0.1 g:5 mL, and then coat it on the ceramic tube 1 to form a gas-sensitive material film 2. The thickness of the gas-sensitive material film 2 is 5 μm. A pair of gold electrodes 3 are arranged between the ceramic tube 1 and the gas-sensitive material film 2. Each gold electrode 3 is connected to two platinum leads 4. Figure 11 As shown;

[0060] Step 2.2, after the gas-sensitive material film 2 is completely dried, the ceramic tube is calcined in a muffle furnace at 300°C at a heating rate of 1°C / min for 3 hours to firmly fix it;

[0061] Step 2.3: Pass the spiral nickel-chromium heating coil 5 used to control the working temperature of the sensor through the inside of the ceramic tube 1, and connect the four platinum leads 4 and the two ends of the nickel-chromium heating coil 5 to the hexagonal base 6 to prepare a tubular structure gas sensor. Figure 11 As shown;

[0062] In step 2.4, the tubular structure gas sensor obtained in step 2.3 is aged in an air environment at 200° C. for 7 days to stabilize its structure.

[0063] Example 2

[0064] like Figure 2 As shown, a morphine gas sensor sensitive material, its structure is 3D 10 The porous foam-like network structure formed by the interconnection and assembly of electronic zinc oxide (ZnO) nanoparticles is defined as ZnO-N-2.

[0065] A morphine gas sensor sensitive material is prepared from raw materials including hexahydrate nitric acid (Zn(NO3)2·6H2O), ethanol, polyvinylpyrrolidone (PVP), and ammonia water (NH3·H2O). The solid-liquid ratio is 2.964 g:15 mL:1.308 g:5 mL, and the average molecular weight of the polyvinylpyrrolidone (PVP) is 500,000.

[0066] The morphine gas sensor sensitive material is used for detecting morphine in methanol.

[0067] A gas sensor is a tubular gas sensor coated with the morphine gas sensor sensitive material.

[0068] The method for preparing the gas sensor comprises the following steps:

[0069] Step 1, preparing a morphine gas sensor sensitive material by using a PVP chelating precipitation-chemical blowing calcination method;

[0070] Step 1.1, disperse zinc nitrate hexahydrate (Zn(NO3)2·6H2O) in ethanol solution at a solid-liquid ratio of 2.964 g:15 mL and stir at 25°C until fully dissolved;

[0071] Step 1.2, dispersing polyvinyl pyrrolidone (PVP) in the solution prepared in step 1.1, wherein the average molecular weight of polyvinyl pyrrolidone (PVP) is 500,000 and the solid-liquid ratio is 1.308 g:15 mL, and stirring at 25°C until fully dissolved;

[0072] Step 1.3: Add 5 mL of aqueous ammonia (NH3·H2O) dropwise to the solution prepared in step 1.2 to form a white flocculant, zinc hydroxide (Zn(OH)2), precipitate at the bottom of the solution until the added aqueous ammonia (NH3·H2O) makes the solution clear.

[0073] Step 1.4, the white flocculant zinc hydroxide (Zn(OH)2) produced in step 1.3 was precipitated by air blowing in an oven at 60°C for 12 h;

[0074] Step 1.5, heating the blow-molded product in step 1.4 to 500° C. at a heating rate of 2° C. / min in a muffle furnace, and calcining the mixture for 1.5 h to obtain a morphine gas sensor sensitive material.

[0075] Step 2, preparing a tubular structure gas sensor based on the sensitive material prepared in step 1;

[0076] Step 2.1: Mix the morphine gas sensor sensitive material with deionized water to form a uniform paste with a solid-liquid ratio of 0.5 g:5 mL, and then coat it on the ceramic tube 1 to form a gas-sensitive material film 2. The thickness of the gas-sensitive material film 2 is 20 μm. A pair of gold electrodes 3 are arranged between the ceramic tube 1 and the gas-sensitive material film 2. Each gold electrode 3 is connected to two platinum leads 4. Figure 11 As shown;

[0077] Step 2.2, after the gas-sensitive material film 2 is completely dried, the ceramic tube is calcined in a muffle furnace at 350°C for 2 hours at a heating rate of 2°C / min to firmly fix it;

[0078] Step 2.3: Pass the spiral nickel-chromium heating coil 5 used to control the working temperature of the sensor through the inside of the ceramic tube 1, and connect the four platinum leads 4 and the two ends of the nickel-chromium heating coil 5 to the hexagonal base 6 to prepare a tubular structure gas sensor, such as Figure 11 As shown;

[0079] In step 2.4, the tubular structure gas sensor obtained in step 2.3 is aged in an air environment at 300° C. for 5 days to stabilize its structure.

[0080] Example 3

[0081] like Figure 3 As shown, a morphine gas sensor sensitive material, its structure is 3D 10 The porous foam network structure formed by the interconnection and assembly of electronic zinc oxide (ZnO) nanoparticles is defined as ZnO-N-3.

[0082] A morphine gas sensor sensitive material is prepared from raw materials including hexahydrate nitric acid (Zn(NO3)2·6H2O), ethanol, polyvinyl pyrrolidone (PVP), and ammonia water (NH3·H2O). The solid-liquid ratio is 10 g:15 mL:2.616 g:7 mL, and the average molecular weight of the polyvinyl pyrrolidone (PVP) is 200,000.

[0083] The morphine gas sensor sensitive material is used for detecting morphine in methanol.

[0084] A gas sensor is a tubular gas sensor coated with the morphine gas sensor sensitive material.

[0085] The method for preparing the gas sensor comprises the following steps:

[0086] Step 1, preparing a sensitive material for a morphine gas sensor;

[0087] Step 1.1, disperse zinc nitrate hexahydrate (Zn(NO3)2·6H2O) in ethanol solution at a solid-liquid ratio of 10 g:15 mL and stir at 30°C until fully dissolved;

[0088] Step 1.2, dispersing polyvinyl pyrrolidone (PVP) in the solution prepared in step 1.1, wherein the average molecular weight of polyvinyl pyrrolidone (PVP) is 200,000 and the solid-liquid ratio is 2.616 g:15 mL, and stirring at 30°C until fully dissolved;

[0089] Step 1.3: Add 7 mL of aqueous ammonia (NH3·H2O) dropwise to the solution prepared in step 1.2 to form a white flocculant, zinc hydroxide (Zn(OH)2), precipitate at the bottom of the solution until the added aqueous ammonia (NH3·H2O) makes the solution clear.

[0090] Step 1.4, the white flocculant zinc hydroxide (Zn(OH)2) produced in step 1.3 was precipitated by air blowing in a 70°C oven for 18 h;

[0091] Step 1.5, heating the blow-molded product in step 1.4 to 600° C. in a muffle furnace at a heating rate of 3° C. / min, and calcining the mixture for 2 h to obtain a morphine gas sensor sensitive material.

[0092] Step 2, preparing a tubular structure gas sensor based on the sensitive material prepared in step 1;

[0093] Step 2.1: Mix the morphine gas sensor sensitive material with deionized water to form a uniform paste with a solid-liquid ratio of 0.7 g:5 mL, and then coat it on the ceramic tube 1 to form a gas-sensitive material film 2. The thickness of the gas-sensitive material film 2 is 30 μm. A pair of gold electrodes 3 are arranged between the ceramic tube 1 and the gas-sensitive material film 2. Each gold electrode 3 is connected to two platinum leads 4. Figure 11 As shown;

[0094] Step 2.2, after the gas-sensitive material film 2 is completely dried, the ceramic tube is calcined in a muffle furnace at 400°C at a heating rate of 3°C / min for 2.5 hours to firmly fix it;

[0095] Step 2.3: Pass the spiral nickel-chromium heating coil 5 used to control the working temperature of the sensor through the inside of the ceramic tube 1, and connect the four platinum leads 4 and the two ends of the nickel-chromium heating coil 5 to the hexagonal base 6 to prepare a tubular structure gas sensor, such as Figure 11 As shown;

[0096] In step 2.4, the tubular structure gas sensor obtained in step 2.3 is aged in an air environment at 350° C. for 4 days to stabilize its structure.

[0097] Example 4

[0098] like Figure 4 As shown, a morphine gas sensor sensitive material, its structure is 3D 10 The porous foam network structure formed by interconnected assembly of electronic zinc oxide (ZnO) nanoparticles is defined as ZnO-N-4.

[0099] A morphine gas sensor sensitive material is prepared from raw materials including hexahydrate nitric acid (Zn(NO3)2·6H2O), ethanol, polyvinyl pyrrolidone (PVP) and ammonia water (NH3·H2O), with a solid-liquid ratio of 20g:15mL:10g:10mL. The average molecular weight of the polyvinyl pyrrolidone (PVP) is 8000.

[0100] The morphine gas sensor sensitive material is used for detecting morphine in methanol.

[0101] A gas sensor is a tubular gas sensor coated with the morphine gas sensor sensitive material.

[0102] The method for preparing the gas sensor comprises the following steps:

[0103] Step 1, preparing a morphine gas sensor sensitive material by using a PVP chelating precipitation-chemical blowing calcination method;

[0104] Step 1.1, disperse zinc nitrate hexahydrate (Zn(NO3)2·6H2O) in ethanol solution at a solid-liquid ratio of 20 g:15 mL and stir at 40°C until fully dissolved;

[0105] Step 1.2, dispersing polyvinyl pyrrolidone (PVP) in the solution prepared in step 1.1, wherein the average molecular weight of polyvinyl pyrrolidone (PVP) is 8000 and the solid-liquid ratio is 10 g:15 mL, and stirring at 40°C until fully dissolved;

[0106] Step 1.3: Add 10 mL of aqueous ammonia (NH3·H2O) dropwise to the solution prepared in step 1.2 to form a white flocculant, zinc hydroxide (Zn(OH)2), precipitate at the bottom of the solution until the added aqueous ammonia (NH3·H2O) makes the solution clear.

[0107] Step 1.4, the white flocculant zinc hydroxide (Zn(OH)2) produced in step 1.3 was precipitated by air blowing in an oven at 80°C for 24 h;

[0108] Step 1.5, heating the blow-molded product in step 1.4 to 700° C. in a muffle furnace at a heating rate of 5° C. / min, and calcining the mixture for 1 hour to obtain a morphine gas sensor sensitive material.

[0109] Step 2, preparing a tubular structure gas sensor based on the sensitive material prepared in step 1;

[0110] Step 2.1: Mix the morphine gas sensor sensitive material with deionized water to form a uniform paste with a solid-liquid ratio of 1 g:5 mL, and then coat it on the ceramic tube 1 to form a gas-sensitive material film 2. The thickness of the gas-sensitive material film 2 is 50 μm. A pair of gold electrodes 3 are set between the ceramic tube 1 and the gas-sensitive material film 2. Each gold electrode 3 is connected to two platinum leads 4, as shown in FIG. Figure 11 As shown;

[0111] Step 2.2, after the gas-sensitive material film 2 is completely dried, the ceramic tube is calcined in a muffle furnace at 500°C at a heating rate of 5°C / min for 0.5 h to firmly fix it;

[0112] Step 2.3: Pass the spiral nickel-chromium heating coil 5 used to control the working temperature of the sensor through the inside of the ceramic tube 1, and connect the four platinum leads 4 and the two ends of the nickel-chromium heating coil 5 to the hexagonal base 6 to prepare a tubular structure gas sensor, such as Figure 11 As shown;

[0113] In step 2.4, the tubular structure gas sensor obtained in step 2.3 is aged in an air environment at 400° C. for 3 days to stabilize its structure.

[0114] Experimental verification

[0115] See also Figure 5 , as proved by XRD patterns, the morphine gas sensor sensitive materials in the above Examples 1 to 4 (i.e., ZnO-N-1, ZnO-N-2, ZnO-N-3, ZnO-N-4) are typical ZnO nanomaterials.

[0116] The gas sensors prepared from the morphine gas sensor sensitive materials (i.e., ZnO-N-1, ZnO-N-2, ZnO-N-3, and ZnO-N-4) in Examples 1 to 4 above were used to conduct experimental verification of morphine drug detection in methanol. The test process mechanism is as follows: Figure 6 As shown, the following steps are included:

[0117] Step 3.1, connect the gas sensors prepared from ZnO-N-1, ZnO-N-2, ZnO-N-3, and ZnO-N-4 to a Fluke 8846a high-precision digital multimeter, respectively. Use a current source to control the temperature of the heating wire inside the ceramic tube, thereby controlling the specific operating temperature of the sensor.

[0118] Step 3.2, the gas sensors prepared by ZnO-N-1, ZnO-N-2, ZnO-N-3, and ZnO-N-4 were transferred to the air of the first test chamber to maintain stability;

[0119] In step 3.3, the gas sensors prepared with ZnO-N-1, ZnO-N-2, ZnO-N-3, and ZnO-N-4 were placed in the second test chamber, which was injected with 100 ppm methanol gas using a microsyringe. The resistance signal value when it stabilized was marked as Rg1.

[0120] In step 3.4, the gas sensors prepared by ZnO-N-1, ZnO-N-2, ZnO-N-3, and ZnO-N-4 were respectively mixed with a 100 ppm standard methanol solution containing morphine (10 mg·L -1 ) gas is transferred to the third test chamber, and the resistance is marked as Rg when it is stable;

[0121] In step 3.5, the gas sensors prepared by ZnO-N-1, ZnO-N-2, ZnO-N-3, and ZnO-N-4 were transferred to the second test chamber, and the resistance values ​​gradually recovered to Rg1;

[0122] Step 3.6, then the gas sensors prepared by ZnO-N-1, ZnO-N-2, ZnO-N-3, and ZnO-N-4 are transferred to the first test chamber and restored to the initial state, thereby completing a test process.

[0123] The sensitivity response value of the sensor to morphine detection is expressed as S=Rg / Rg1.

[0124] By testing the change in resistance value of the gas sensor before and after, it can be proved whether methanol contains morphine drugs. The test results are intuitive and do not require professional personnel to perform data analysis and processing, making it easy for non-professionals to use.

[0125] like Figure 7 As shown, the response intensity of the gas sensors prepared by ZnO-N-1, ZnO-N-2, ZnO-N-3, and ZnO-N-4 first increases with increasing temperature, reaches a maximum value at 250°C, and then shows a downward trend with further increasing temperature. The response value is highest at the optimal working temperature of 250°C. Among them, the response intensity of the gas sensor prepared by ZnO-N-1 reaches 2.6 (dimensionless unit), the gas sensor prepared by ZnO-N-2 reaches 5.6 (dimensionless unit), the gas sensor prepared by ZnO-N-3 reaches 4.4 (dimensionless unit), and the gas sensor prepared by ZnO-N-4 reaches 3.5 (dimensionless unit), which proves that the gas sensor prepared by the sensitive material of the present invention can successfully detect morphine drugs in methanol.

[0126] Figure 8(a) is a graph showing the response value changes of the gas sensor prepared using ZnO-N-2 in Example 2 at the optimal operating temperature (250°C) to morphine standard solutions of different concentrations in a methanol background, and Figure 8(b) is a fitting graph showing the response value changes of the gas sensor prepared using ZnO-N-2 in Example 2 at the optimal operating temperature (250°C) to morphine standard solutions of different concentrations in a methanol background. The test data show that the response value of the ZnO-N-2 sensor to a 2ppm morphine standard solution in a methanol background can reach 1.12 (dimensionless units). This indicates that the prepared ZnO-N-2 sensor has a low detection limit. And as can be seen from Figure 8(b), there is a good linear relationship between the concentration of the morphine standard solution and its response in a methanol background.

[0127] Figure 9This is a bar graph of the response values ​​of the gas sensor prepared using ZnO-N-2 in Example 2 to different types of detection gases under a methanol background at the optimal operating temperature (250°C). The sensor's selectivity was analyzed by detecting 100ppm of various drugs and volatile organic compounds, such as ketamine standard solution, methamphetamine standard solution, ethanol, toluene, acetone, and acetic acid, under a methanol background. The results show that the ZnO-N-2 sensor has the highest response value to morphine standard solution under a methanol background, indicating that the sensor has unique selectivity for morphine standard solution under a methanol background.

[0128] Figure 10 This figure shows the stability test of the gas sensor prepared using the ZnO-N-2 gas sensor described in Example 2. To evaluate the long-term stability of the ZnO-N-2 gas sensor, the sensor was subjected to a 30-day gas sensing performance test. The test showed that the ZnO-N-2 sensor maintained a response of approximately 5.0 (dimensionless units) to a 100 ppm morphine standard solution in a methanol background at 250°C, with a fluctuation range of <10%, demonstrating good long-term stability.

[0129] Figure 12 The gas sensor prepared with ZnO-N-2 in Example 2 was tested at the Guangdong Customs. Within 90 days, 197 customs clearance applications for goods carrying methanol-like liquids were collected, and each product was tested for morphine at a dosage of 100 ppm. To avoid misjudgment due to environmental factors, products with a sensitivity response value of S ≥ 2 (dimensionless units) were identified as suspicious. Two products were found to have S values ​​greater than 2 (dimensionless units), namely 5.8 (dimensionless units) and 11.3 (dimensionless units). After laboratory LC-MS analysis, both products were found to contain morphine, with contents of 10.3 mg·L -1 and 21.2 mg·L -1 This shows that the sensor has extremely high recognition accuracy and detection application feasibility for morphine drugs in methanol.

Claims

1. A morphine gas sensor sensitive material, characterized in that: The sensitive material has 3D 10 A porous foam-like network structure formed by interconnected assembly of electronic zinc oxide (ZnO) nanoparticles.

2. A morphine gas sensor sensitive material, characterized in that: The preparation raw materials include: zinc nitrate hexahydrate (Zn(NO3)2·6H2O), anhydrous ethanol, polyvinyl pyrrolidone (PVP) and ammonia water (NH3·H2O), the solid-liquid ratio is (0.1-20) g:15 mL: (0.1-10) g: (1-10) mL, and the average molecular weight of polyvinyl pyrrolidone (PVP) is 8000-700000.

3. Application of morphine gas sensor sensitive material, characterized in that, The morphine gas sensor sensitive material according to any one of claims 1 to 2 is applied to the detection of morphine in methanol.

4. A gas sensor, characterized in that: The gas sensor is a tubular gas sensor coated with the morphine gas sensor sensitive material according to any one of claims 1 to 2.

5. A method for preparing a gas sensor according to claim 4, characterized in that: The steps include: Step 1, preparing a morphine gas sensor sensitive material by using a PVP chelating precipitation-chemical blowing calcination method; Step 2: Prepare a tubular structure gas sensor based on the sensitive material prepared in step 1.

6. The preparation method according to claim 5, characterized in that The step 1 specifically includes the following steps: Step 1.1, disperse zinc nitrate hexahydrate (Zn(NO3)2·6H2O) in anhydrous ethanol solution at a solid-liquid ratio of (0.1-20) g:15 mL, and stir at 20-40°C until fully dissolved; Step 1.2, dispersing polyvinyl pyrrolidone (PVP) in the solution prepared in step 1.1, wherein the average molecular weight of polyvinyl pyrrolidone (PVP) is 8000-700000, the solid-liquid ratio is (0.1-10) g:15 mL, and stirring at 20-40° C. until fully dissolved; Step 1.3, add 1-10 mL of aqueous ammonia (NH3·H2O) dropwise to the solution prepared in step 1.2 to form a white flocculant zinc hydroxide (Zn(OH)2) precipitate at the bottom of the solution until the added aqueous ammonia (NH3·H2O) makes the solution clear; Step 1.4, precipitating the white flocculant zinc hydroxide (Zn(OH)2) produced in step 1.3 by air blowing in an oven at 25-80°C for 0.5-24h; Step 1.5: blow-molded product in step 1.4 in a muffle furnace at 1-5°C / min. -1 The heating rate is increased to 300-700°C and the mixture is kept warm and calcined for 1-3 hours to finally prepare a morphine gas sensor sensitive material.

7. The preparation method according to claim 5, characterized in that The step 2 specifically includes the following steps: Step 2.1, mixing the morphine gas sensor sensitive material with deionized water to form a uniform paste with a solid-liquid ratio of (0.1-1.0) g:5 mL, and then coating the paste on a ceramic tube (1) to form a gas-sensitive material film (2), wherein the thickness of the gas-sensitive material film (2) is 5-50 μm, and a pair of gold electrodes (3) are provided between the ceramic tube (1) and the gas-sensitive material film (2), and each gold electrode (3) is connected to two platinum leads (4); Step 2.2, after the gas-sensitive material film (2) is completely dried, the ceramic tube is calcined in a muffle furnace at 300-500° C. at a heating rate of 1-5° C. / min for 0.5-3 h to fix it tightly; Step 2.3: Pass a spiral nickel-chromium heating coil (5) for controlling the operating temperature of the sensor through the interior of the ceramic tube (1), and connect four platinum leads (4) and both ends of the nickel-chromium heating coil (5) to a hexagonal base (6) to prepare a tubular structure gas sensor; Step 2.4: age the tubular structure gas sensor obtained in step 2.3 in an air environment at 200-400° C. for 3-7 days to stabilize its structure.

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