An aldehyde gas detection method, a test strip and a preparation method thereof

Abstract

The present invention relates to a method for detecting aldehyde gas, a test strip and a preparation method thereof, belonging to the technical field of organic analytical chemistry, and solves the problems of complicated pretreatment, long time consumption, high detection cost and insufficient detection sensitivity for low-abundance aldehydes in the prior art. The aldehyde gas detection method involved in the present invention uses a metal nanomaterial modified with a probe molecule to capture aldehyde gas through a chemical reaction, fixes the aldehyde gas on a carrier loaded with the metal nanomaterial, and then elutes the reaction product of the probe molecule and the aldehyde gas from the metal nanomaterial for mass spectrometry detection; the probe molecule contains a mercapto group and an amino group. It realizes rapid, efficient and highly sensitive specific capture and detection of aldehyde molecules in a gas phase environment.

Description

Technical Field

[0001] The present invention relates to the technical field of organic analytical chemistry, and in particular to a method for detecting aldehyde gas, a test strip and a preparation method thereof. Background Art

[0002] Human production activities and daily life will emit a large amount of volatile organic compounds (VOCs) into the atmosphere. The increasingly serious problem of VOCs emissions and their impact on air quality are considered important issues in the field of environmental protection. Therefore, the detection of VOCs in the atmospheric environment has been receiving much attention. In recent years, VOCs have been found to be able to serve as biomarkers for cancer, and significant upregulations of various VOCs biomarkers can be detected in the plasma, urine, sweat, breath, etc. of cancer patients. Among them, the detection of cancer biomarkers in exhaled breath has received much attention in recent years due to the non-invasive nature of exhaled breath sample collection and the advantage of continuous sample supply.

[0003] Aldehyde molecules are a type of VOCs molecules with relatively high activity. The detection of gaseous aldehyde molecules not only has important applications in environmental monitoring but also plays an important role in the early screening of cancer, especially lung cancer. In the detection of aldehyde molecules in exhaled breath, two types of detection methods based on chromatography / mass spectrometry and sensors have been reported and developed. However, the chromatography / mass spectrometry method has problems such as complicated pretreatment, cumbersome detection steps, and long detection time, and the sensor method is difficult to be applied to the detection of actual samples due to sensitivity limitations. Therefore, a method that is more low-cost, rapid, portable, and easy to use needs to be established and applied to the early screening process of cancer as soon as possible.

[0004] Traditional methods can only detect gaseous aldehydes such as formaldehyde and acetaldehyde. The detection methods are mostly limited to the use of the classic silver mirror reaction, that is, aldehydes react with silver hydroxide ammonia to undergo an oxidation-reduction reaction, and silver ions are reduced by aldehydes to form silver mirrors for qualitative and quantitative analysis of aldehydes. And most of the detections in the prior art can only achieve qualitative detection, and there are few that can accurately perform quantitative detection. The main problems in the detection of aldehyde gas in the prior art are as follows: (1) The traditional method has a complex process and high requirements for instrument equipment; (2) It is difficult to form an accurate and effective measurement of aldehydes; (3) Sampling in remote areas cannot be detected, and it is impossible to bring the sample back to a detectable laboratory for analysis and measurement through fixed sampling. Summary of the Invention

[0005] In view of the above analysis, the present invention aims to provide a method for detecting aldehyde gas, a test strip and a preparation method thereof, so as to solve the problems of complicated pretreatment, long time consumption, high detection cost, or insufficient detection sensitivity for low-abundance aldehydes in the existing aldehyde gas detection.

[0006] The present invention relates to a method for detecting aldehyde gas. A metal nanomaterial modified with a probe molecule captures aldehyde gas through a chemical reaction, fixes the aldehyde gas on a carrier loaded with the metal nanomaterial, and then elutes the reaction product of the probe molecule and the aldehyde gas from the metal nanomaterial for mass spectrometry detection;

[0007] The probe molecule contains a mercapto group and an amino group.

[0008] Further, the probe molecule is p-aminothiophenol.

[0009] Further, the metal nanomaterial is a silver nanomaterial.

[0010] Further, the preparation method of the metal nanomaterial modified with the probe molecule includes:

[0011] Step 1. Add the probe molecule solution to the aqueous metal nitrate solution, stir evenly to obtain a mixed solution of the probe molecule and silver nitrate;

[0012] Step 2. Add the aqueous sodium borohydride solution to the mixed solution of the probe molecule and the metal nitrate obtained in Step 1, continue to stir to obtain a silver nanosol, and let it stand;

[0013] Step 3. Concentrate and redisperse the silver nanosol to prepare a dispersion of the metal nanomaterial modified with the probe molecule.

[0014] Further, it includes:

[0015] Step a. Select a carrier and load the metal nanomaterial modified with the probe molecule on the carrier;

[0016] Step b. Place the carrier loaded with the metal nanomaterial modified with the probe molecule in the gas environment to be measured and the internal standard gas environment respectively, and keep it for 15 to 20 minutes;

[0017] Step c. Take out the carrier from the gas environment, place it in front of the mass spectrometry inlet for detection.

[0018] Further, in Step c, it includes:

[0019] Step c1. Take out the carrier from the gas environment and place it in front of the mass spectrometry inlet;

[0020] Step c2. Clamp the carrier with a metal clip and apply a high voltage of more than 3000 V to the carrier through the metal clip;

[0021] Step c3. Elute the reaction product of the probe molecule and the aldehyde gas on the carrier with a thiol solution, send it into the mass spectrometer for detection, and calculate the aldehyde content according to the content of the internal standard molecule.

[0022] Further, in step c3, the thiol solution is a methanol solution of dodecyl mercaptan.

[0023] On the one hand, the present invention relates to an aldehyde gas detection test strip, comprising: a base paper and an aldehyde gas capture agent loaded on the base paper, wherein the capture agent is a metal nanomaterial modified with a probe molecule, and the probe molecule contains a mercapto group and an amino group.

[0024] Further, the probe molecule is p-aminothiophenol; and / or the metal nanomaterial is a silver nanomaterial.

[0025] On the other hand, the present invention relates to a preparation method of an aldehyde gas detection test strip for preparing the above-mentioned aldehyde gas detection test strip, which is characterized by comprising:

[0026] Step 1. Add a probe molecule solution to an aqueous silver nitrate solution and stir evenly to obtain a mixed solution of the probe molecule and silver nitrate.

[0027] Step 2. Add an aqueous sodium borohydride solution to the mixed solution of the probe molecule and silver nitrate obtained in step 1, continue to stir to obtain a silver nanosol, and let it stand.

[0028] Step 3. Concentrate and redisperse the silver nanosol to prepare a dispersion of silver nanoparticles modified with a probe molecule.

[0029] Step 4. Drop the dispersion of silver nanoparticles modified with the probe molecule prepared in step 3 onto a filter paper. Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0030] (1) The present invention adopts a novel mass spectrometry ionization source - paper spray ionization source, and can realize the capture, separation and detection of complex samples through a simple filter paper. Due to the advantages of low cost, easy processing, good biocompatibility, easy storage and easy transportation of the paper itself, this method is extremely suitable for sampling complex samples and is also very suitable for sampling in remote and resource - underdeveloped areas.

[0031] (2) The present invention directly combines paper spray with mass spectrometry. Based on the advantages of fast, efficient, highly sensitive, powerful qualitative function of mass spectrometry and also capable of quantitative detection by adding internal standards, this method can realize the quantitative detection of various gas aldehyde molecules.

[0032] (3) The present invention uses silver nanomaterials wrapped with p-aminothiophenol. This organic small molecule can simultaneously serve as a stabilizer on the surface of the nanomaterial and a probe molecule for capturing gas aldehyde molecules. The nanomaterial is directly loaded on the paper by dropping it onto the paper, which is convenient and fast.

[0033] (4) The present invention utilizes the characteristic that the liquid film formed on the paper surface has an accelerating effect on the reaction, which can accelerate the reaction process and improve the capture efficiency during the process of capturing gas molecules. The specific method is relatively simple. Before capturing the gas, ten microliters of methanol is dropped onto the paper surface to form a methanol liquid film. Utilizing this characteristic of accelerating the reaction, the detection limit of the test paper provided by the present invention for detecting benzaldehyde molecules is lower than 0.1 ppt, as Figure 2 shown.

[0034] (5) The present invention uses a methanol solution of dodecyl mercaptan to elute the product obtained from the reaction between the probe molecules on the surface of the silver nanomaterial and aldehyde molecules. This solution also serves as the spray solution for paper spray mass spectrometry. After elution, direct injection is carried out without a separate elution step. The total time for elution and sample measurement is about one minute, which greatly shortens the detection time and improves the throughput of the method.

[0035] (6) The present invention adopts a method of low-temperature storage (-20 °C). When stored at room temperature for 3 days, it can be detected that the signal of the benzaldehyde molecules captured by the test paper decreases significantly, indicating that the benzaldehyde molecules may desorb from the test paper surface. The present invention adopts a method of low-temperature storage, as Figure 3 shown, and it can be detected that there is no significant change in the signal of the benzaldehyde molecules captured by the test paper within 7 days, indicating that the desorption rate of benzaldehyde molecules from the test paper surface decreases significantly under low-temperature conditions, which is beneficial to the storage and transportation of the test paper.

[0036] In the present invention, the above technical solutions can also be combined with each other to achieve more preferred combination schemes. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can be made obvious from the description, or understood by implementing the present invention. The objectives and other advantages of the present invention can be realized and obtained through the content specifically pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The drawings are only used for the purpose of showing specific embodiments and are not considered as limitations on the present invention. Throughout the drawings, the same reference signs represent the same components.

[0038] Figure 1 is a schematic diagram of the detection principle of the aldehyde detection test paper of the present invention.

[0039] Figure 2 is the detection limit of the aldehyde gas detection test paper of the present invention for detecting the gas benzaldehyde.

[0040] Figure 3 respectively show the test paper stored under normal temperature (20 °C) and low temperature (-20 °C) conditions.

[0041] Figure 4a is the adsorption curve for the quantitative detection of benzaldehyde in Example 1.

[0042] Figure 4b It is the standard curve obtained after taking the double logarithm in Example 1.

[0043] Figure 5a It is the secondary mass spectrum of the product obtained from the reaction of acetaldehyde and p-aminothiophenol measured with an aldehyde gas detection test strip in Example 2.

[0044] Figure 5b It is the secondary mass spectrum of the product obtained from the reaction of butyraldehyde and p-aminothiophenol measured with an aldehyde gas detection test strip in Example 2. Detailed implementation manners

[0045] The present invention provides a method for detecting aldehyde gas. A metal nanomaterial modified with a probe molecule captures aldehyde gas through a chemical reaction, fixes the aldehyde gas on a carrier loaded with the metal nanomaterial, and then elutes the reaction product of the probe molecule and the aldehyde gas from the metal nanomaterial and performs mass spectrometry detection; the probe molecule contains a mercapto group and an amino group.

[0046] In a possible solution, the probe molecule is p-aminothiophenol.

[0047] p-Aminothiophenol serves both as a stabilizer in the synthesis process of the nanomaterial and as a probe molecule to specifically capture gaseous aldehyde molecules. p-Aminothiophenol has two active groups, an amino group and a mercapto group. The amino group can react with aldehydes to form imines, i.e., Schiff bases. The two pairs of lone pairs of electrons on the sulfur atom of the mercapto group have good coordination ability and can produce a certain coordination effect with metal atoms. At the same time, the metal nanoparticles have good surface adsorption ability, can adsorb p-aminothiophenol tightly through the phase interface on the metal surface, and adsorb the imine formed by the reaction of p-aminothiophenol and aldehydes on the surface of the metal nanoparticles. In this way, the chemical capture of aldehyde gas molecules is realized, and it is fixed on the carrier through a chemical reaction.

[0048] In a possible solution, the metal nanomaterial is a silver nanomaterial.

[0049]

[0050] The present invention also provides the above-mentioned method for detecting aldehyde gas, including:

[0051] Step a. Select a carrier and load the probe molecule on the carrier;

[0052] Step b. Place the carrier loaded with the probe molecule in the gas environment to be measured and the internal standard gas environment respectively, and keep for 15 to 20 minutes;

[0053] Step c. Take out the carrier loaded with the reaction product of the probe molecule and aldehyde from the gas environment, place it in front of the mass spectrometry inlet, and perform detection.

[0054] The detection principle of the test strip is as follows Figure 1 As shown, it should be noted that in the above step a, the carrier is made of a material with liquid absorption capacity. Specifically, the carrier can be paper and can be cut according to needs, and the common cutting shapes are rectangle and triangle for use requirements.

[0055] In step b, in order to achieve more sensitive detection, during the process of Schiff base reaction to capture gas aldehyde molecules, 10 μL of methanol solvent is dropped on the carrier to form a liquid film on the surface of the test strip, realizing liquid film acceleration, improving the reaction rate, increasing the product yield, and reducing the detection limit of the detection.

[0056] Specifically, in step c, it includes

[0057] Step c1. Take out the carrier loaded with the reaction product of the probe molecule and aldehyde from the gas environment and place it in front of the mass spectrometry inlet.

[0058] Step c2. Clamp the carrier with a metal clip and apply a high voltage of more than 3000V to the carrier through the metal clip.

[0059] Step c3. Elute the reaction product of the probe molecule and aldehyde with a thiol solution, send it to the mass spectrometry for detection, and calculate the aldehyde content according to the content of the internal standard molecule.

[0060] Specifically, the thiol solution in step c3 is a methanol solution of dodecyl mercaptan.

[0061] Specifically, the concentration of the methanol solution of dodecyl mercaptan is 0.015 - 0.025 mol / L, and the volume ratio of dodecyl mercaptan to the silver nanomaterial sol wrapped with p-aminothiophenol is 2.5:1. The concentration of the methanol solution of dodecyl mercaptan should not be too low, so as not to affect the detection sensitivity due to insufficient elution. At the same time, the methanol solution of dodecyl mercaptan should not be too high, so as not to inhibit the ionization state of the analyte during the spraying process due to the high concentration of thiol, resulting in a decrease in the mass spectrometry signal.

[0062] It should be noted that the thiol solution is a methanol solution of dodecyl mercaptan. This thiol solution has two functions: one is to elute the imine ions obtained from the reaction of p-aminothiophenol and aldehyde small molecules from the silver nanomaterial, and the other is to serve as the spraying solution required for the paper spray process, playing the role of conducting electricity and generating spray droplets, and atomizing the analyte sample in the mass spectrometry.

[0063]

[0064] Since dodecyl mercaptan is an aliphatic mercaptan, its sulfur atom is different from the sulfur atom of the phenolic mercapto group of p-aminothiophenol. There is a certain conjugation effect between the sulfur atom of the phenolic mercapto group and the benzene ring, which weakens the coordination ability of the lone pair electrons on the sulfur atom. However, the sulfur atom of dodecyl mercaptan has no conjugation with the aromatic ring and is a stronger Lewis base with stronger coordination ability. Dodecyl mercaptan coordinates and complexes with silver, replaces the ligand of imine p-aminothiophenol, and elutes it substantially through a chemical reaction. To ensure that dodecyl mercaptan elutes all the imine p-aminothiophenol, the more dodecyl mercaptan is used, the better. However, excessive use will cause waste of reagents and signal suppression during the ionization process. Therefore, the volume ratio of dodecyl mercaptan to the silver nanomaterial sol encapsulated by p-aminothiophenol is controlled at 2.5:1.

[0065] The present invention also provides an aldehyde gas detection test strip, comprising: a base paper and an aldehyde gas molecule capture agent loaded on the base paper, and the capture agent is a metal nanomaterial modified with a probe molecule, and the probe molecule contains a mercapto group and an amino group.

[0066] Specifically, the probe molecule is p-aminothiophenol.

[0067] Specifically, the metal nanomaterial is a silver nanomaterial.

[0068] Specifically, the base paper of the test strip is filter paper, and the filter paper is filter paper with a loose porous structure and a pore size of 100 - 120 mm.

[0069] The test strip is a carrier of aldehyde gas and has a certain influence on the absorption of aldehyde gas and the adsorption of the fixing agent. It is very suitable to use filter paper as the base paper. Filter paper has good liquid absorption performance, is not easy to break, and is convenient for storage and transportation. The pore size of the filter paper is 100 - 120 mm. This kind of filter paper has a loose porous structure and a large specific surface area, which is conducive to the adsorption of gas molecules on its surface.

[0070] Specifically, the average particle size of the silver nanoparticles is 7 - 9 nm.

[0071] The silver nanoparticles act on the phenolic mercapto group through coordination. At the same time, the surface of the silver nanoparticles has good interfacial adsorption, and has good adsorption effects on both p-aminothiophenol and the imine after the reaction with aldehyde. It has been found through research that the particle size of the silver nanoparticles has a certain influence on the adsorption ability, and the adsorption effect is the best when the average particle size is 7 - 9 nm.

[0072] The present invention also provides a preparation method of the above-mentioned aldehyde gas detection test strip. It includes:

[0073] Step 1. At room temperature, add the p-aminothiophenol solution to the silver nitrate aqueous solution and stir evenly;

[0074] Step 2. The newly prepared sodium borohydride aqueous solution was added dropwise to the reaction system, and stirring was continued for 5 minutes to obtain a brown silver nanosol, which was left overnight.

[0075] Step 3. The silver nanosol was concentrated tenfold using an ultrafiltration centrifuge tube, and the sol was resuspended with water to obtain p-aminothiophenol-modified silver nanoparticles.

[0076] Specifically, the p-aminothiophenol solution is a p-aminothiophenol methanol solution obtained by dissolving p-aminothiophenol in methanol.

[0077] It should be noted that silver-related compounds and particles have certain photosensitivity and are prone to side reactions under light irradiation. The above process should be protected from light during storage.

[0078] Specifically, in the p-aminothiophenol methanol solution, the concentration of p-aminothiophenol in Step 1 is 3 - 8 mmol / L, the concentration of the silver nitrate aqueous solution is 0.3 - 0.8 mmol / L, and the molar ratio of p-aminothiophenol to silver nitrate is 1:1. The concentration of silver nitrate should not be too high to prevent the aggregation of the obtained silver nanosol. To prevent the precipitation of silver nitrate in the methanol solution, a scheme with a volume ratio of water in the silver nitrate solution to methanol in the p-aminothiophenol methanol solution of 10:1 is adopted. Therefore, the initial concentration of p-aminothiophenol is 10 times that of silver nitrate to ensure that the two react in a molar ratio of 1:1. Feeding in this ratio can prevent the excess of p-aminothiophenol small molecules from remaining free in the system and affecting subsequent measurements, and can also ensure that p-aminothiophenol as a protective agent is sufficient and will not cause the aggregation of the silver nanosol.

[0079] Specifically, the concentration of the newly prepared sodium borohydride aqueous solution in Step 2 is 7 - 15 mmol / L, and the molar ratio of sodium borohydride to silver nitrate is 0.4:1 - 0.5:1.

[0080] Sodium borohydride is a good reducing agent that reduces silver ions in the system to obtain silver nanoparticles. To ensure the complete reduction reaction, the molar ratio of sodium borohydride to silver nitrate should be greater than 0.25:1. At the same time, an excessive amount of sodium borohydride will cause waste of reagents. Therefore, the molar ratio of sodium borohydride to silver nitrate is controlled at 0.4:1 - 0.5:1.

[0081] It should be noted that the above-mentioned aldehyde gas molecule detection test paper can be directly coupled with a mass spectrometer after capturing aldehyde gas to complete quantitative detection. In remote areas, due to the characteristics of paper being suitable for storage and transportation, and the rate of gas molecule desorption from the paper surface can be significantly reduced under low-temperature storage conditions. After the test paper captures aldehyde gas, it can be stored and transported at low temperature to a mass spectrometry laboratory for centralized detection, making up for the drawback that medical devices and instrument resources are lacking in remote areas and thus it is not suitable for medical detection. In addition, the combination of paper spray and portable mass spectrometry is very convenient, and on-site real-time detection can be achieved through their combination.

[0082] The preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings. The accompanying drawings form a part of this application and are used together with the embodiments of the present invention to illustrate the principle of the present invention, and are not used to limit the scope of the present invention.

[0083] The quadrupole-time-of-flight mass spectrometer (Q-TOF MS) used in the following embodiments is of the model Impact HD (Bruker Daltonics).

[0084] The filter paper used in the following embodiments is No. 1 filter paper purchased from Whatman. A copper alligator clip is clamped at the end of the paper strip, and a high-voltage direct current of 3000 - 3500 V is applied to the alligator clip through a wire. The tip of the paper strip is placed 3 - 5 mm away from the mass spectrometry inlet for subsequent mass spectrometry detection.

[0085] The dodecyl mercaptan solution used in the following embodiments is a methanol solution of 0.02 M dodecyl mercaptan, and the methanol solvent is HPLC-grade methanol. 25 μL of the mercaptan solution used as the elution and spray solvent is added to the end of the paper strip with a pipette.

[0086] Example 1

[0087] Prepare an aldehyde gas detection test paper and use it to quantitatively analyze gas benzaldehyde molecules:

[0088] Preparation of the aldehyde gas detection test paper:

[0089] Step 1. At room temperature, add 2 mL of a 5 mmol / L p-aminothiophenol methanol solution to 20 mL of a 0.5 mmol / L silver nitrate aqueous solution and stir evenly;

[0090] Step 2. Gradually add 400 μL of a freshly prepared 10 mmol / L sodium borohydride aqueous solution dropwise to the reaction system, continue to stir for 5 minutes to obtain a brown silver nanosol, and let it stand overnight;

[0091] Step 3. Concentrate the sol tenfold with an ultrafiltration centrifuge tube and resuspend the sol with water to obtain p-aminothiophenol-coated silver nanoparticles.

[0092] Quantitative determination of gaseous benzaldehyde:

[0093] For the quantitative analysis of benzaldehyde molecules, we used p-tolualdehyde gas as an internal standard. The benzaldehyde gas to be measured and the internal standard gas were mixed in a certain proportion, and were simultaneously captured and detected by the test paper, as Figure 4a and Figure 4b shown. The ratio of the characteristic ion peak with the strongest signal in the secondary mass spectrum of the reaction products of the two was used as the quantitative basis (214.1→136.0 / 228.1→136.0). The concentration of the internal standard molecule was 100 ppt, and the concentration range of benzaldehyde molecules was 10 ppt - 1 ppm. The linear range could reach six orders of magnitude, which was very suitable for the detection of ppb-level aldehyde gases.

[0094] Step a. Cut the filter paper into a triangle with a size of 2 cm × 1.5 cm (bottom × height), with an apex angle of about 60°. Clamp a copper alligator clip at the end of the paper strip, and add 10 μL of the silver nanomaterial sol wrapped with p-aminothiophenol to obtain the test paper.

[0095] Step b. Place the test paper in the gas environment to be measured and the internal standard gas environment respectively, then add 10 μL of methanol solvent to form a liquid film, and keep it at 60 °C for 15 minutes.

[0096] Step c. Take out the test paper, place it directly in front of the mass spectrometry inlet, apply a high voltage of 3500 V to the filter paper through the copper clip, and then elute the products captured by the test paper with a methanol solution of dodecyl mercaptan, and send them into the mass spectrometer for detection. Calculate the aldehyde content according to the content of the internal standard molecule.

[0097] Step d. Perform secondary mass spectrometry determination on the product ions obtained from the reaction of the two molecules at the mass spectrometry end, and adopt the multiple reaction monitoring (MRM) mode of the mass spectrometer. Process the obtained results, and obtain the adsorption curve of benzaldehyde molecules with different concentrations on the surface of the aldehyde gas molecule test paper. By performing double logarithmic processing on this curve, a standard curve can be fitted. The mathematical model of this curve conforms to the Freundlich adsorption isotherm and can be used as a reliable basis for quantification.

[0098] To further verify the ability of this method to accurately detect benzaldehyde molecules, we added a certain concentration of benzaldehyde to the exhaled breath of healthy volunteers to detect the spike recovery rate of this method in exhaled breath. The detection method was the same as described above. We detected three spiked samples, added different levels of benzaldehyde concentrations respectively, and each sample was detected three times. The spike recovery rate and relative standard deviation were calculated. The results are shown in Table 1.

[0099] Table 1 Spike recovery rate of benzaldehyde in the exhaled breath of healthy volunteers

[0100] Number Spiked Concentration / PPB Detected Concentration / PPB Spiked Recovery Rate (%) Relative Standard Deviation 1 692 683 0.987 1.07％ 2 74.4 69.8 0.939 4.52％ 3 9.08 8.38 0.923 5.12％

[0101] Example 2

[0102] Prepare an aldehyde gas detection test strip and use it for qualitative analysis to detect various gaseous aldehyde molecules.

[0103] Preparation of the aldehyde gas detection test strip:

[0104] Step 1. At room temperature, add 2 mL of a 5 mmol / L p-aminothiophenol methanol solution to 20 mL of a 0.5 mmol / L silver nitrate aqueous solution and stir evenly.

[0105] Step 2. Gradually add 400 μL of a freshly prepared 10 mmol / L sodium borohydride aqueous solution dropwise to the reaction system, continue stirring for 5 minutes to obtain a brown silver nanosol, and let it stand overnight.

[0106] Step 3. Concentrate the silver nanosol tenfold with an ultrafiltration centrifuge tube, and redisperse the sol with water to obtain silver nanoparticles wrapped with p-aminothiophenol.

[0107] Qualitative analysis and determination of various gaseous aldehyde molecules such as acetaldehyde and butyraldehyde:

[0108] For the determination of various gaseous aldehyde molecules, we respectively prepared gas atmospheres of different aldehydes at 1000 ppm, which were captured and detected by the test strip respectively, and the mass spectrometry peaks of the reaction products were qualitatively identified by tandem mass spectrometry. The attribution of the fragment peaks in their tandem mass spectra was respectively identified, and these aldehyde molecules could be accurately qualitatively determined by the characteristic peaks of tandem mass spectrometry.

[0109] Step a. Cut the filter paper into a triangle with a size of 2 cm × 1.5 cm (bottom × height), with the apex angle approximately 60°. Clamp the copper alligator clip at the end of the paper sheet, and drop 10 μL of the silver nanomaterial sol wrapped with p-aminothiophenol to obtain the detection test strip.

[0110] Step b. Place the detection test strip in each of the aldehyde gas atmospheres to be measured respectively, then drop 10 μL of methanol solvent to form a liquid film, and keep it at 60 °C for 15 minutes.

[0111] Step c. Take out the test strip, place it directly in front of the mass spectrometry inlet, apply a high voltage of 3500 V to the filter paper through the copper clip, then elute the products captured by the test strip with a methanol solution of dodecyl mercaptan, send it to the mass spectrometer for detection, and select specific first-order mass spectrometry peaks for tandem mass spectrometry identification. The data of the tandem mass spectrometry characteristic peaks of different aldehyde molecules are listed in Table 2.

[0112] Table 2 Tandem mass spectrometry characteristic peaks of different aldehyde molecules

[0113]

[0114] Taking acetaldehyde and butyraldehyde as examples, the secondary spectrum is as Figure 5a and Figure 5b . According to the fragmentation rules of the secondary mass spectrometry, the structures of the main mass spectrometry peaks were analyzed respectively. The results of the secondary mass spectrometry show that the aldehyde gas detection test paper can be used for the detection and identification of various gas aldehyde molecules. Combining with Example 1, this test paper can also perform quantitative analysis on these aldehyde molecules, and has the ability to specifically detect aldehyde molecules in a complex gas matrix, which has very wide application value.

[0115] As mentioned above, it is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for detecting aldehyde gas, characterized in that, a metal nanomaterial modified with a probe molecule captures aldehyde gas through a chemical reaction, fixes the aldehyde gas on a carrier loaded with the metal nanomaterial, and then elutes the reaction product of the probe molecule and the aldehyde gas from the metal nanomaterial and performs mass spectrometry detection; the probe molecule contains a mercapto group and an amino group; the probe molecule is p-aminothiophenol; the metal nanomaterial is a silver nanomaterial; p-aminothiophenol has two active groups, amino and mercapto. The amino group reacts with aldehyde to form an imine, namely Schiff base. The two pairs of lone pairs of electrons of the sulfur atom of the mercapto group have good coordination ability and produce a certain coordination effect with metal atoms: The aldehyde gas detection method described above includes: Step a. Select a carrier and load the metal nanomaterial modified with the probe molecule on the carrier; Step b. Place the carrier loaded with the metal nanomaterial modified with the probe molecule in the gas environment to be measured and the internal standard gas environment respectively, and keep for 15 to 20 minutes; Step c. Take out the carrier from the gas environment and place it in front of the mass spectrometry inlet for detection; in step c, it includes: Step c1. Take out the carrier from the gas environment and place it in front of the mass spectrometry inlet; Step c2. Clamp the carrier with a metal clip and apply a high voltage of more than 3000V to the carrier through the metal clip; Step c3. Elute the reaction product of the probe molecule and the aldehyde gas on the carrier with a thiol solution, send it into the mass spectrometer for detection, and calculate the aldehyde content according to the content of the internal standard molecule; In step c3, the thiol solution is a methanol solution of dodecyl mercaptan; the thiol solution elutes the imine ions obtained from the reaction of p-aminothiophenol and aldehyde small molecules from the silver nanomaterial. Dodecyl mercaptan coordinates and complexes with silver, replaces the ligand of p-thiophenol of imine, and elutes it substantially through a chemical reaction; the thiol solution serves as the spray solution required for the paper spray process, plays the role of conducting electricity and generating spray droplets, and atomizes the sample to be measured in the mass spectrometer; The concentration of the methanol solution of dodecyl mercaptan is 0.015 - 0.025 mol / L.

2. The aldehyde gas detection method according to claim 1, characterized in that, The preparation method of the metal nanomaterial modified with the probe molecule includes: Step 1. Add the p-aminothiophenol solution to the silver nitrate aqueous solution, stir evenly to obtain a mixed solution of p-aminothiophenol and silver nitrate; Step 2. Add the sodium borohydride aqueous solution to the mixed solution of p-aminothiophenol and silver nitrate obtained in step 1, continue to stir to obtain silver nanosol, and let it stand; Step 3. Concentrate and resuspend the silver nanosol to prepare a dispersion of p-aminothiophenol-modified silver nanomaterial.

3. An aldehyde gas detection test paper, characterized in that, It includes: A backing paper and an aldehyde gas capturer loaded on the backing paper, wherein the capturer is a metal nanomaterial modified with a probe molecule, and the probe molecule contains a mercapto group and an amino group; the probe molecule is p-aminothiophenol; the metal nanomaterial is a silver nanomaterial; p-aminothiophenol has dual active groups of amino and mercapto. The amino group reacts with aldehyde to form an imine, i.e., Schiff base. The two pairs of lone pair electrons of the sulfur atom of the mercapto group have good coordination ability and produce a certain coordination effect with metal atoms:

4. A preparation method of an aldehyde gas detection test paper for preparing the aldehyde gas detection test paper according to claim 3, characterized in that, it includes: Step 1. Add a probe molecule solution to an aqueous silver nitrate solution, stir evenly to obtain a mixed solution of the probe molecule and silver nitrate; Step 2. Add an aqueous sodium borohydride solution to the mixed solution of the probe molecule and silver nitrate obtained in Step 1, continue stirring to obtain a silver nanosol, and let it stand; Step 3. Concentrate and redisperse the silver nanosol to prepare a dispersion of probe molecule-modified silver nanoparticles; Step 4. Drop the dispersion of probe molecule-modified silver nanoparticles prepared in Step 3 onto filter paper; The probe molecule is p-aminothiophenol.

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