Method for detecting amine-type compounds in air

Abstract

The present invention relates to a nanoporous sensor composed of a silicate sol-gel matrix containing a reagent composition, said reagent composition comprising a mixture of 4-(dimethylamino)-cinnamaldehyde and polystyrene sulfonic acid, its preparation process and its use in a method for detecting at least one amine-type compound, said compound being selected from hydrazine, ethanolamine, ammonia and morpholine. **

Description

Title of the invention: Method for detecting amine-type compounds in the air Technical field

[0001] The present invention relates to a novel method for detecting and optionally quantifying amine-type compounds, in particular hydrazine (N2H4), in the air.

[0002] Hydrazine is a substance classified as CMR (IARC 2B-EU IB). In 2011, it was included in the REACH regulation's candidate list of substances of very high concern (in English "candidate list of substances of very high concern"). In 2017, the European Union lowered its OEL (Occupational Exposure Limit Value over 8 hours) by a factor of 10, imposing a new threshold of 10 ppb (0.013 mg / m3), applicable no later than January 17, 2020. In addition to the human health aspect, hydrazine is classified as very toxic to aquatic organisms (EU classification H400 and H410).

[0003] Due to its CMR character, hydrazine is no longer an oxidant for rockets, but remains used in many fields, notably as an intermediate in organic synthesis in the pharmaceutical and chemical industries, or as a blowing agent for polymer foams, or as a reducer for metal salts or even as a corrosion inhibitor in the water of industrial boiler circuits, for example.

[0004] Due to its toxicity, the assessment of risks associated with environmental hydrazine releases is important and requires the ability to detect and optionally quantify the presence of hydrazine in the environment.

[0005] The assessment of these risks is currently severely limited by the metrology associated with this substance, particularly concerning direct in-situ measurement. Indeed, despite the fact that relatively sensitive and specific analytical methods exist (final reading by HPLC-UV), these cannot be implemented easily or be compatible with industrial practices. The “instantaneous response” analytical methods are neither selective enough nor precise and sensitive enough to allow the expected concentrations of gaseous hydrazine in the final discharges to be assessed.

[0006] The detection and quantification of hydrazine are currently carried out via an indirect method. This method involves sampling the ambient air to be analyzed and trapping the hydrazine in an acidified cartridge, then desorbing it and reacting it with a reagent solution. The addition compounds formed are then separated by liquid chromatography and analyzed optically.

[0007] In addition to the duration of this method which involves several stages which are difficult to carry out readable directly at the sampling location, potential interferences with other nitrogenous gaseous compounds are not known, particularly in the potential presence of interferents used to alkalize the water or resulting from the degradation of hydrazine, such as ethanolamine (NH2EtOH), morpholine, or ammonia (NH3). It is important to be able to selectively measure hydrazine directly in a concentration range of 1 to 100 ppb in dry to very humid air and in the presence of interferents whose concentration can be 50 to 100 times higher than that of hydrazine.

[0008] The method which is the subject of the present invention provides a solution to these problems.

[0009] Indeed, the method according to the invention makes it possible to detect and optionally selectively quantify hydrazine in the presence of water vapor, volatile organic compounds and other nitrogen compounds such as ethanolamine (NH2EtOH), morpholine or ammonia. Upon contact with hydrazine, the sensor used changes color and the intensity of coloring is proportional to the hydrazine content, which makes it possible to detect and potentially quantify this compound. Prior art

[0010] The detection of hydrazine has been the subject of numerous studies and the detection methods are as numerous as they are varied due to the high chemical reactivity of this compound. Therefore, only the methods proposed in the literature, capable of covering the desired concentration range of 1.3 to 130 pg.m-3 (i.e. 1 to 100 ppb), are described here.

[0011] Methods for measuring hydrazine in air are fewer than those for the liquid phase, particularly in the targeted range of 1.3 to 130 pg.m-3 (i.e. 1 to 100 ppb). The current measurement method is described in INRS Data Sheet 21. It is based on the use of benzaldehyde [*]. Hydrazine is sampled by air suction through a tube filled with an inert adsorbent (Chromosorb P NAW or equivalent) with a 3060 Mesh particle size, impregnated with sulfuric acid. The contents of the cartridge are desorbed with deionized water and a derivatization by benzaldehyde is carried out. The addition compound, benzalazine, is measured by liquid chromatography (HPLC) coupled with optical detection in the UV [2 3]. This method makes it possible to detect 30 ppb of hydrazine in 15 minutes of sampling.

[0012] A variant of this method is the use of a cassette containing two glass fiber filters impregnated with sulfuric acid. The extraction of hydrazine is carried out with an EDTA buffer solution and the derivatization is carried out with benzaldehyde. The benzalazine formed is measured by liquid chromatography coupled with optical detection in the UV [4]. This assay method proves to be sensitive, since it It is possible to detect 0.017 ppb of N2H4.

[0013] These two methods do not allow direct measurement at the sampling site and the interference of ammonia or other amines at high concentrations 50 to 100 times higher than that of hydrazine is not known.

[0014] Direct measurement methods are also available. In the context of monitoring worker exposure to hydrazine, monomethylhydrazine (MMH) and 1,1-dimethylhydrazine (UDMH) used as rocket fuels in air bases and space centers in the United States, several colorimetric dosimeters have been developed and marketed by laboratories [5 6]. The principle is based on the incorporation of an aromatic aldehyde such as vanillin, para-dimethylaminobenzaldehyde (pDMAB) or 2,4-Dinitrobenzaldehyde onto a filter paper or an inert surface. Hydrazine and MMH react with vanillin or 2,4-Dinitrobenzaldehyde to form a yellow compound, while the product formed with pDMAB is orange. UDMH reacts with 2,4-Dinitrobenzaldehyde to form a yellow compound and there is no reaction with vanillin and pDMAB.Colorimetric dosimeters based on vanillin and para-dimethylaminobenzaldehyde are marketed by the company DODTEC [7] and CHEMSEE [8]. They do not allow exact quantification but only to estimate the levels of hydrazine, monomethylhydrazine in the air from 25 ppb and up to 1.2 ppm.

[0015] In patent US005719061A [9], Rose-Pehrsson et al. propose a method for the selective detection and quantification of liquid or gaseous hydrazine, monomethylhydrazine and 1,1-dimethylhydrazine by derivatization with aromatic carboxyaldehydes and fluorometric analysis. The selectivity is based on the reactivity of 3 derivatization agents, ortho-phthalaldehyde (OPA), naphthalene 2,3-dicarboxaldehyde (NDA) and anthracene 2,3-dicarboxaldehyde (ADA) with hydrazine, monomethylhydrazine and 1,1-dimethylhydrazine as a function of the pH of the reagent solution. These authors have therefore developed a complex device which allows ambient air to be pumped to bubble it into a reagent solution whose composition (OPA or NDA or AD A) and pH must be modified to obtain selectivity.Even if the detection limit reached is ppb, the analysis of the gas mixture to be analyzed requires numerous steps of changing reagents and pH, followed by fluorimetric analyses. Furthermore, there is no interference study, particularly with other amines at concentrations 50 to 100 times higher, which are likely to modify the pH of the solution.

[0016] For precise measurements, a few commercial devices exist. The portable electrochemical detector from the company InterScan, model 4180-100b

[10] can detect hydrazine in the range of 10 to 100 ppb in less than 1 second, with a high detection limit of 10 ppb. The method is also not selective because the sensor also detects NH3, NOx, CO and other organic amines.

[0017] High sensitivity can be achieved using devices equipped with a photoionization detector (PID) such as ppbRAE 3000 from RAE f11]. The photoionization detector, equipped with a 10.6 eV lamp, can ionize hydrazine and measure a few ppbs in 3 seconds. However, the detection is not selective because a large number of volatile organic compounds present in the air whose ionization potential is lower than 10.6 eV are also detected, such as NH3, ethanolamine and morpholine.

[0018] The ionization of hydrazine followed by a measurement of ion mobility using ion mobility spectrometry, in English Ion Mobility Spectrometer (IMS) makes it possible to achieve contents of the order of ten ppb (20 - 30 ppb) while being selective with the choice of carrier gas. With the use of a radioactive source, the IMS (such as the portable detector SABRE 4000

[12] or ChemProlOOi from Environics

[13] must be under the responsibility of a person competent in radiation protection. This technique is favored by armies and police forces for the detection of chemical weapons and illicit products. Its application in the public domain has developed more recently with the development of new non-radioactive ionization sources (Corona effect) such as the portable detector PAIMS from the company MaSaTECH

[14] or LCD 3.3 from Smiths Détection

[15] .

[0019] The state of the art of hydrazine measurements shows that the only simple method currently adopted, using benzaldehyde as reagent, can be used with good selectivity and sensitivity. However, the measurement of hydrazine in the air compartment requires the steps of adsorption then desorption and derivatization followed by optical analysis which are difficult to carry out on site. In addition, for this method, interferences with high concentrations of NH3, ethanolamine or morpholine gas in the atmosphere are not known.

[0020] There is therefore a real need for a method for direct detection and optionally direct quantification of hydrazine in the air, selective for hydrazine, compatible with the presence of high concentrations of interferents, easy to implement in the field.

[0021] The method according to the invention addresses these issues. Summary

[0022] A first object of the invention is a nanoporous sensor composed of a nanoporous silicate sol-gel matrix containing a composition of reagents, said composition of reagents comprising a mixture of 4-(dimethylamino)-cinnamaldehyde and polystyrene sulfonic acid.

[0023] Another object of the invention is a method for preparing a nanoporous sensor according to the invention, said method comprising the following steps: a. Synthesis of a sol from an organosilylated precursor, the synthesis being carried out in a solvent, said solvent comprising water, in the presence of 4-(dimethylamino)-cinnamaldehyde and polystyrene sulfonic acid;

[0024] b. Gelling of the sol obtained in step a), so as to obtain a gel;

[0025] c. Drying the gel obtained in step b), so as to obtain a nanoporous sensor.

[0026] The present invention also relates to a method for detecting at least one amine-type compound, said compound being chosen from hydrazine, ethanolamine, ammonia and morpholine, using a nanoporous sensor according to the invention, said method comprising the steps of: a. bringing a gaseous sample to be analyzed into contact with said nanoporous sensor,

[0027] b. detecting said amine-type compound(s) on said nanoporous sensor.

[0028] Another subject of the invention is the use of a nanoporous sensor according to the invention, for the detection and / or quantification of at least one amine-type compound, said compound being chosen from hydrazine, ethanolamine, ammonia and morpholine.

[0029] The present invention also relates to a device for detecting at least one amine-type compound, said compound being chosen from hydrazine, ethanolamine, ammonia and morpholine, in a gaseous sample to be analyzed, said device comprising a cell containing a nanoporous sensor according to the invention and comprising:

[0030] - a gas inlet;

[0031] - a gas outlet;

[0032] - an optical input;

[0033] - an optical output. Brief description of the drawings

[0034] Other characteristics, details and advantages will appear on reading the detailed description below, and on analyzing the attached drawings, in which: Fig.l

[0035] [Fig.l] shows the scheme of the reaction between N2H4 and DMACA catalyzed in acid medium with formation of DMACA-N2H4 (compound 3) and 2DMACA-N2H4 (compound 4). Fig. 2

[0036] [Fig.2] shows the differential spectra obtained at different times showing the evolution of the absorbance of the DMACA-N2H4 and 2DMACA-N2H4 complexes in the nanoporous sensor Hy3 during the exposure of the sensor to a gas mixture flow containing 14 ppb of N2H4. A spectrum is collected every 5 min from 0 to 60 min. Fig. 3

[0037] [Fig.3] shows the differential spectra obtained at different times showing the evolution of the absorbance of neutral DMACA in the Hylau nanoporous sensor during exposure of the sensor to a gas mixture flow containing 5 ppm of NH3. A spectrum is collected every 5 min from 0 to 50 min. Fig. 4

[0038] [Fig.4] shows the diagram of an example of a device according to the invention. Fig. 5

[0039] [Fig.5] shows the diagram of an example of circulation of the gas flow around the nanoporous sensor placed in the cell according to a particular embodiment of the invention. Fig. 6

[0040] [Fig.6] shows the diagram of an example of a cell of the device according to the invention.

[0041] Fig. 7

[0042] [Fig.7] shows: on the left the evolution of the absorption spectrum of the Hyl sensor exposed to 5 ppm of NH3, a spectrum is collected every 5 minutes for 50 minutes; on the right the variation of the rate of formation of neutral DMACA as a function of the concentration of NH3. Flux = 200 mL-min *, %RH = 50%. Fig. 8

[0043] [Fig.8] shows the calibration curve of the Hy3 sensor for the detection of N2H4. Variation of the formation rate of the 1DMACA-N2H4 complex at 388 nm as a function of the N2H4 concentration. Flux = 200 mL-min *, %RH = 50%. Fig. 9

[0044] [Fig.9] shows the effect of the relative humidity of the gas mixture on the speed of formation of the 1DMACA-N2H4 complex as a function of the N2H4 concentration. Flux = 200 mL-min *. Fig. 10

[0045] [Fig. 10] shows the effect of the presence of a potential interferent, NH2EtOH, on the response of the Hy3 sensor to hydrazine. Flux = 200 mL-min *, RH = 50%. [Fig.11]

[0046] [Fig. 11] shows the effect of the presence of a potential interferent, morpholine, on the response of the Hy3 sensor to hydrazine. Flux = 200 mL-min *, HR = 50%. Fig. 12

[0047] [Fig. 12] shows the effect of the presence of a potential interferent, NH3, on the response of the Hy3 sensor to hydrazine. Flux = 200 mL-min *, RH = 50%. Fig. 13

[0048] [Fig. 13] shows the effect of the presence of two potential interferents, NH3 and NH2 EtOH, on the response of the Hy3 sensor to hydrazine. Flux = 200 mL-min *, HR = 50%. Fig. 14

[0049] [Fig. 14] shows the effect of the presence of two potential interferents, NH3 and morpholine, on the response of the Hy3 sensor to hydrazine. Flux = 200 mL-min *, HR = 50%. Fig. 15

[0050] [Fig. 15] shows the comparison of the responses of the Hyl, Hy2 and Hy3 sensors at 30 ppb of N2H4. Flux = 200 mL-min *, %RH = 50%. Fig. 16

[0051] [Fig. 16] shows the comparison of the responses of the Hy8 and Hy9 sensors at 40 ppb of N2 H4. Flux = 200 mL-min *, %RH = 50%. Fig. 17

[0052] [Fig. 17] shows the comparison of the responses of sensors Hy4, Hy5, Hy6 and Hy7 at 25 ppb N2H4. Flux = 200 mL-min *, %RH = 50%. Detailed description

[0053] The present invention relates to a nanoporous sensor composed of a nanoporous silicate sol-gel matrix containing a composition of reagents, said composition of reagents comprising a mixture of 4-(dimethylamino)-cinnamaldehyde and polystyrene sulfonic acid.

[0054] For the purposes of the present invention, the term “silicate sol-gel matrix” means a material obtained by a sol-gel process consisting of using as precursors silicon alkoxides of formula Si(OR)x where R is an alkyl group.

[0055] During the sol-gel process, the alkoxy groups (OR) are hydrolyzed in the presence of water into silanol groups (Si-OH). The latter condense, forming siloxane bonds (Si-O-Si-). Small particles are then formed, generally less than 1 μm in size, which aggregate and form clusters that remain in suspension without precipitating, forming a sol. The increase in clusters and their condensation increase the viscosity of the medium, which gels. A porous solid material is obtained by drying the gel, with the expulsion of the solvent outside the polymer network formed (syneresis). The sol-gel matrices obtained from silicon alkoxides of formula Si(OR)x are called silicate sol-gel matrices in the present application.

[0056] For the purposes of the present invention, the term nanoporous means: the pores of which have a size of less than 100 nm.

[0057] According to a particular embodiment, the nanoporous matrix according to the invention is an essentially microporous matrix. Thus, according to this embodiment, the sensor can also be described as essentially microporous. Essentially microporous material (essentially microporous sensor or essentially microporous matrix) is defined as a material in which at least 80% of the pores are micropores.

[0058] Micropores are characterized according to the IUP AC definition by a width that does not exceed 2 nm (IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by AD McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997). Online version (2019-) created by SJ Chalk. ISBN 0-9678550-9-8. https: / / doi.org / 10.1351 / goldbook).

[0059] Upon contact with an amine-type compound, and in particular gaseous hydrazine, the nanoporous sensor according to the invention changes color due to the formation of DMACA-N2H4 and 2DMACA-N2H4 complexes by reaction between hydrazine (N2H4) and 4-(dimethylamino)-cinnamaldehyde (DMACA) in the presence of polystyrene sulfonic acid which makes it possible to catalyze this reaction. The variations in absorbance are correlated with the hydrazine content in the air.

[0060] The reaction between hydrazine (N2H4) and 4-(dimethylamino)-cinnamaldehyde (DMACA) is advantageously catalyzed by an acid derived from a polymer, in particular polystyrene sulfonic acid. The choice of this type of acid and in particular polystyrene sulfonic acid has many advantages.

[0061] First, this acid is a high molecular weight polymer which has an SO3H acid function for each styrenic monomer. As a result, the number of available protons is particularly high and makes it possible to adjust the acidity of the pores to catalyze the reaction between DMACA and N2H4.

[0062] Furthermore, inorganic acids and organic acids of low molecular weight have the disadvantage of possible release of acid vapor during the drying step of the sol-gel matrix, the acid therefore being likely to evaporate also in this case. Thus, a volatile inorganic acid such as HCl (or an organic acid such as acetic acid) would risk evaporating from the sol-gel matrix, which would cause a loss of efficiency or even prevent the sensor from functioning. This disadvantage is not present for acids derived from a polymer, such as polystyrene sulfonic acid, because these are not volatile.

[0063] Finally, another major advantage of polymer-derived acids concerns the deployment of the acidic polymer chains in the small pores of the sol-gel matrix. This deployment of acidic functional groups in the pores makes it possible, on the one hand, to acidify each pore and, on the other hand, to strongly restrict the diffusion of the polymer in the porous network, preventing it from migrating towards the surface of the sensor. The advantages of this method compared to the one currently used with the trapping of hydrazine in cartridges followed by a delayed derivatization with the benzaldehyde reagent are numerous. The sensor according to the invention allows: direct measurement of hydrazine on site; - the measurement of hydrazine, in particular via the measurement of the absorbance of the addition compound DMACA-N2H4 at 388 nm ([Fig.l]); - the measurement of hydrazine by sampling the air to be analyzed with a flow rate which can vary from 10 to 600 mL.min *, for example a flow rate of 200 mL.min *, the sampling time being able to vary depending on the concentration of the gas to be detected, for example between 60 min and 5 min, here respectively for 1 and 100 ppb of hydrazine detected; - the selective measurement of hydrazine in the concentration range 1-85 ppb in the presence of interferents such as NH3, ethanolamine (NH2EtOH) or morpholine, when the total concentration of potential interferents is less than 200 times the concentration of hydrazine ([N2H4]); - the selective measurement of hydrazine in gas mixtures with relative humidity levels varying between 25 and 100%.

[0064] Advantageously, the nanoporous sensor according to the invention is characterized by a large specific adsorption surface area. Indeed, it has a specific adsorption surface area of ​​700 to 2500 m2.g *, preferably of 800 to 2000 m2.g *.

[0065] The specific adsorption surface area, pore volume and pore size distribution are determined by analysis of the liquid nitrogen adsorption-desorption isotherm with the DFT (Density Functional Theory) model. The BET (Brunauer, Emmett and Teller) method is an analytical method that allows the specific adsorption surface area to be deduced.

[0066] The nanoporous sensor according to the invention preferably has a pore volume of 0.1 to 0.9 cm3.g ', preferably of 0.2 to 0.8 cm3.g ', even more preferably of 0.2 to 0.6 cm3.g '. The pore volume represents the volume occupied by the pores per gram of sensor. The pore volume of the material is obtained from the nitrogen adsorption isotherm at the temperature of liquid nitrogen.

[0067] Advantageously, the nanoporous sensor according to the invention has a proportion of micropores greater than 75%, preferably greater than 80%, preferably ranging from 85% to 95%, the remainder to 100% corresponding to the proportion of mesopores.

[0068] According to the IUP AC definition (IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by AD McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997). Online version (2019-) created by SJ Chalk. ISBN 0-9678550-9-8. https: / / doi.org / 10.1351 / goldbook), micropores are defined as pores with a width not exceeding 2 nm, mesopores pores with a width between 2 and 50 nm. Pores with a width greater than 50 nm are macropores according to the same IUP AC reference.

[0069] The nanoporous sensor according to the invention preferably has a proportion of mesopores of less than 25%, preferably less than 20%, more preferably ranging from 5% to 15%, the remainder to 100% corresponding to the proportion of micropores.

[0070] In particular, the nanoporous sensor according to the invention may have micropores having a diameter ranging from 0.3 to 2 nm, preferably from 0.5 to 2 nm.

[0071] The nanoporous sensor according to the invention can also be characterized in that it advantageously has mesopores having a diameter of between 2 and 20 nm, preferably between 2 and 15 nm.

[0072] The nanoporous sensor according to the invention preferably has a ratio r of the concentrations of polystyrene sulfonic acid and 4-(dimethylamino)-cinnamaldehyde of 1 to 20, preferably of 2 to 15, even more preferably 10.

[0073] This ratio is calculated from the molar concentrations of polystyrene sulfonic acid and 4-(dimethylamino)-cinnamaldehyde (r = [H+] / [DMACA]). For this calculation, the molar mass of the polystyrene sulfonic acid monomer (M = 184 g / mol) is used to convert the mass concentration of polystyrene sulfonic acid (PSS) into a molar concentration. For example, a PSS concentration of 9.2 gL 1 corresponds to a concentration of 0.05 mol. L 1 (= 9.2 / 184). Thus, with a DMACA concentration of 5.103 mol. L 1 and a PSS concentration of 9.2 gL 1 (0.05 mol. L1), the ratio r is equal to 10.

[0074] The ratio of the concentrations of polystyrene sulfonic acid and 4-(dimethylamino)-cinnamaldehyde can also be expressed with a ratio r' of the mass concentrations of the two species (r1 = [H+] / [DMACA]), this ratio r' ranging from 1 to 20, preferably from 2 to 15, even more preferably 11. For example, with a DMACA concentration of 5.103 mol.L 1 corresponding to 0.876 gL 1 (with M = 175.23 g.mol ') and a PSS concentration of 9.2 gL *, the ratio r' is equal to 10.5.

[0075] The present invention also relates to the method for preparing the nanoporous sensor according to the invention, said method comprising the following steps: a. Synthesis of a sol from a selected organosilylated precursor, the synthesis being carried out in a solvent, said solvent comprising water, in the presence of 4-(dimethylamino)-cinnamaldehyde and polystyrene sulfonic acid;

[0076] b. Molding of the sol obtained in step a), followed by its gelling so as to obtain a gel;

[0077] c. Drying of the gel obtained in step b), followed by its demolding so as to obtain a nanoporous sensor.

[0078] According to a preferred embodiment of the process according to the invention, the organosilylated precursor is chosen from precursors with rapid hydrolysis and condensation and not comprising long hydrophobic chains such as tetramethoxysilane Si(OCH3)4), methyltrimethoxysilane CH3Si(OCH3)3, ethyltrimethoxysilane (C2H5)Si(OCH3)3, 3-aminopropyltriethoxysilane (C3H6NH2)Si(OC2H5)3, 3-aminopropyltrimethoxysilane (C3H6NH2)Si(OCH3)3), (3-(methylamino)propyl)trimethoxysilane (C3H6NHCH3)Si(OCH3)3, 3-carboxypropyltriethoxysilane (C3H6CO2H)Si(OC2H5)3, 3-carboxypropyltrimethoxysilane (Si(C3H6CO2H)(OCH3)3), tetraethoxysilane and their mixture. The precursor is preferably chosen from tetramethoxysilane (TMOS), tetraethoxysilane (TEOS) and their mixture.

[0079] Step a) of the process according to the invention is preferably carried out in a solvent which may be water or a water / alcohol mixture, the alcohol preferably being a C1 to C6 aliphatic alcohol, more preferably methanol or ethanol, or a mixture of water with a solvent chosen from acetone, formamide, methyl ethyl ketone.

[0080] In the process according to the invention, step a) of synthesis of the sol is advantageously carried out initially by mixing an organosilylated precursor chosen from tetramethoxysilane Si(OCH3)4), methyltrimethoxysilane CH3Si(OCH3)3, ethyltrimethoxysilane (C2H5)Si(OCH3)3, 3-aminopropyltriethoxysilane (C3H6NH2 )Si (OC2H5)3, 3-aminopropyltrimethoxysilane (C3H6NH2)Si(OCH3)3), (3-(methylamino)propyl)trimethoxysilane (C3H6NHCH3)Si(OCH3)3, 3-carboxypropyltriethoxysilane (C3H6CO2H)Si(OC2H5)3, 3-carboxypropyltrimethoxysilane (Si(C3H6CO2H)(OCH3)3), tetraethoxysilane and their mixture, with 4-(dimethylamino)-cinnamaldehyde in the solvent, said solvent comprising water, then adding in a second step polystyrene sulfonic acid.

[0081] The addition of polystyrene sulfonic acid is preferably carried out dropwise because the dissolution of the acid in the mixture is exothermic. Alternatively, the addition of the polystyrene sulfonic acid solution can be carried out by adding to the mixture the organosilylated precursor and 4-(dimethylamino)-cinnamaldehyde in the solvent, this mixture being maintained at a temperature below 10°C.

[0082] According to a preferred embodiment, step a) of the process according to the invention is characterized in that the molar ratio of the organosilylated precursor to the solvent ranges from 1 / 20 to 1 / 2, preferably from 1 / 18 to 1 / 3, even more preferably from 1 / 16 to 1 / 4.

[0083] Advantageously, step a) of the process according to the invention is carried out at room temperature, the term room temperature designating a temperature of approximately 20-22°C.

[0084] According to a preferred embodiment, the mixture obtained at the end of step a) is kept stirring before the gelling step b). Preferably, this stirring is carried out at room temperature for a period ranging from 2 to 48 hours, preferably 24 hours.

[0085] Step b) of gelling can be carried out after casting the mixture obtained at the end of step a) into a mold. When a mold has been used in this way, the method according to the invention can then comprise, after step c) of drying, a step of demolding the nanoporous sensor.

[0086] The gelling step b) can advantageously be carried out under a relative humidity level of 100%, at a temperature between 20 and 25°C, preferably 22°C. This step b) preferably has a duration of 1 to 15 days, preferably 1 to 5 days, even more preferably 2 days.

[0087] Step c) of drying can advantageously be carried out in a closed enclosure, for example a desiccator, the humidity and temperature of which are preferably controlled.

[0088] The drying step c) is advantageously carried out by sweeping the closed enclosure with a flow of inert and humid gas, preferably argon. The relative humidity of the applied gas flow can advantageously be controlled, being initially 100%, then decreased in stages until reaching approximately 25%. The humidity in the closed enclosure can thus decrease during the drying step to reach 25 to 28% relative humidity.

[0089] This step c) preferably has a duration of 15 to 60 days, preferably 20 to 40 days.

[0090] After drying, the nanoporous sensor obtained is preferably stored away from light, at a temperature ranging from 2 to 10°C, preferably from 4 to 8°C, even more preferably 6°C.

[0091] The nanoporous sensor according to the invention and obtainable by the method according to the invention advantageously has a parallelepiped shape. It advantageously has dimensions of the order of a millimeter, for example a height of 7.5 to 10.3 mm, a width of 4.8 to 6.4 mm and a thickness of 1 to 1.3 mm.

[0092] The present invention also relates to a method for detecting in a gaseous sample to be analyzed at least one amine-type compound, said compound being chosen from hydrazine, ethanolamine, ammonia and morpholine, using a nanoporous sensor according to the invention, said method comprising the steps of:

[0093] a. bringing said gaseous sample to be analyzed into contact with said nanoporous sensor,

[0094] b. detecting on said nanoporous sensor the said amine-type compound(s) in the gaseous sample to be analyzed.

[0095] This method advantageously makes it possible to selectively measure a compound of the type amine, in particular hydrazine, directly, in a concentration range of 1 to 100 ppb in dry to very humid air and in the presence of interferents whose total concentration can be at most 200 times higher than that of the amine to be detected, in particular hydrazine.

[0096] For the purposes of the present invention, dry air means air with a humidity level of less than or equal to 25%.

[0097] Thus, the method according to the invention makes it possible to carry out measurements on a gaseous sample whose relative humidity level varies between 25 and 100%, preferably from 30 to 100%.

[0098] The method according to the invention therefore has real advantages compared to the methods of the prior art which do not allow this measurement to be carried out directly, whatever the humidity level, over this concentration range and in the presence of interferents.

[0099] In addition to detection, the method according to the invention can also allow the determination in a gaseous sample to be analyzed of the concentration of at least one amine-type compound, said compound being chosen from hydrazine, ethanolamine, ammonia and morpholine. Thus, according to a particular embodiment, the present invention relates to a method for detecting and quantifying in a gaseous sample to be analyzed at least one amine-type compound, said compound being chosen from hydrazine, ethanolamine, ammonia and morpholine, using a nanoporous sensor according to the invention, said method comprising the steps of: a. bringing said gaseous sample to be analyzed into contact with said nanoporous sensor,

[0100] b. detecting and quantifying on said nanoporous sensor the said amine-type compound(s) in the gaseous sample to be analyzed.

[0101] Step b) of the method according to the invention may in particular comprise a step of measuring the absorbance of the nanoporous sensor as a function of time.

[0102] The analytical method which allows the detection and determination of the contents of hydrazine and interferents carrying a primary or secondary amine function by absorbance measurements as a function of time involves knowledge of the absorption spectra of the mixture 4-(dimethylamino)-cinnamaldehyde (DMACA) / polystyrene sulfonic acid (PSS) in the presence of the targeted amine-type compounds for different concentrations of said amine compounds.

[0103] From these absorption spectra, calibration curves representing the temporal evolution of the absorbance as a function of the concentration of each of the said amine-type compounds can be established.

[0104] Thus, when the sensor according to the invention is placed in the presence of a gaseous sample to be analyzed, the absorbance measurement result obtained as a function of time can be correlated with the calibration curves previously established, which leads to determine the presence or absence of an amine-type compound and optionally to determine its concentration.

[0105] The detection and optionally the quantification of hydrazine, ethanolamine, ammonia or morpholine by absorbance measurements is enabled by the reaction taking place between these compounds and 4-(dimethylamino)-cinnamaldehyde (DMACA) in the presence of polystyrene sulfonic acid (PSS) which acts as a catalyst and which results in the formation of complexes which have detectable absorption spectra in the UV-visible range, for example using a spectrophotometer.

[0106] Thus, the reaction between N2H4 and DMACA catalyzed in the presence of polystyrene sulfonic acid gives rise to the formation of the addition complexes, 1DMACA-N2H4 and 2DMACA-N2H4 according to the equations represented in [Fig.l].

[0107] The formation of these two complexes 1DMACA-N2H4 and 2DMACA-N2H4 can be visualized by the absorbance peaks at 388 and 558 nm respectively ([Fig.2]).

[0108] In the context of the present invention, it is the peak at 388 nm which is used to detect and quantify hydrazine because among the two peaks formed it is the one which offers the best sensitivity. Indeed, the 2DMACA-N2H4 complex is formed more slowly and in smaller quantity than the DMACA-N2H4 complex for steric and kinetic reasons.

[0109] With regard to ammonia, DMACA(H+) deprotonates in the presence of a strong base such as NH3, to form neutral DMACA absorbing intensely at 420 nm ([Fig.3]). Detection and measurement of the NH3 concentration can therefore be achieved by measuring the deprotonation rate (corresponding to the ratio of the change in absorbance over time) as a function of the NH3 concentration in the gas mixture ([Fig.7]).

[0110] The present invention also relates to the use of a nanoporous sensor according to the invention for the detection, or quantification or detection and quantification of at least one amine-type compound, said compound being chosen from hydrazine, ethanolamine, ammonia and morpholine.

[0111] The nanoporous sensor according to the invention can be used in dynamic mode or in static mode. Thus the nanoporous sensor can be placed in a gas flow to be analyzed and circulated by a fluid circuit or alternatively the sensor can be placed in an enclosure comprising the gas sample to be analyzed.

[0112] The present invention also relates to a device (1) for detecting at least one amine-type compound, said compound being chosen from hydrazine, ethanolamine, ammonia and morpholine, in a gaseous sample to be analyzed, said device comprising a cell (11) containing a nanoporous sensor according to the invention, said cell comprising: - a gas inlet (111);

[0113] - a gas outlet (112);

[0114] - an optical input (113);

[0115] - an optical output (114).

[0116] Advantageously, the device according to the invention comprises a fluidic circuit adapted to circulate the gaseous sample to be analyzed through the cell (11) by generating a gas flow from the gas inlet (111) to the nanoporous sensor then to the gas outlet (112).

[0117] According to a preferred embodiment, the fluid circuit according to the invention comprises a flow regulator (2) adapted to regulate the flow rate of the gas flow. The flow regulator (2) may be composed of a stop valve (21) and a regulating needle valve (22).

[0118] Advantageously, the device according to the invention further comprises a light source (3) and a spectrophotometer (4), in which the optical input (113) of the cell is connected to the light source (3) and the optical output (114) of the cell is connected to the spectrophotometer (4). The light source (3) and the spectrophotometer (4) can thus constitute the optical analysis part of the device.

[0119] According to a preferred embodiment, the fluid circuit of the device according to the invention further comprises a temperature probe adapted to measure the temperature of the gas flow.

[0120] Advantageously, the device according to the invention further comprises a humidity probe adapted to measure the humidity of the gas flow.

[0121] Advantageously, the device according to the invention further comprises a flow meter (5) adapted to measure the flow rate of the gas flow.

[0122] The fluid circuit can thus take into account: - the flow of gas mixture necessary for the exposure of the sensors, this flow being able to be varied for example between 50 and 600 mL / min depending on the sensor, - the measurement of the temperature and relative humidity of the gas mixture, - a mode for purging the measuring circuit.

[0123] The device according to the invention can thus operate in the following manner: the air or gas sample to be analyzed can be sucked in using a pump (6), which can be miniature, and conducted initially through an inlet distributor (7) where the temperature and humidity of the gas sample will be measured. The distributor (7) can then distribute the gas sample to 2 outlets. The pump can in particular have a flow rate ranging from 50 to 1100 ml / min.

[0124] The first outlet can direct the air towards the cell (11) containing the nanoporous sensor. The cell can be placed upstream of a flow meter (5) connected to an outlet distributor (8) itself connected to the pump (6). The flow meter makes it possible to fix the velocity of the gas flow in the exposure cell.

[0125] The second output of the inlet distributor (7) can be connected to the outlet distributor (8) via a shut-off valve (21) and a regulating needle valve (22). This assembly then constitutes a leak circuit. This configuration makes it possible to vary the exposure flow rate of the sensors (when using different types of sensors) because the pump operates continuously at a fixed flow rate, for example 1.1 L / min. The shut-off valve makes it possible to cut off the leak circuit to purge the measuring circuit if necessary.

[0126] The optical analysis part comprises a light source (3) which can probe the sensor and a spectrophotometer (4), the latter being able to be miniature, which will collect the light transmitted by the sensor and transform it into electric current. The spectrophotometer (4) can operate at wavelengths ranging from UV to IR via the visible, the wavelength being chosen according to the measurement to be carried out.

[0127] The light source (3) may consist of 2 LEDs connected by optical fibers or a miniature lamp. The light source may be a UV or visible or UV-visible source.

[0128] For the detection of hydrazine at 388 nm, NH3 at 420 nm, ethanolamine at 474 nm or morpholine at 490 nm, the combination of a UV LED and a visible LED makes it possible to obtain the wavelength range 380-800 nm. Other choices of LEDs are possible depending on the optical response of the sensor. The light is conveyed to the exposure cell for example using an optical fiber. At the outlet of the exposure cell, the transmitted light is conveyed to the miniature spectrophotometer (4) whose response range is wide, for example from 337.5 to 822 nm.

[0129] An example of a device according to the invention is shown in [Fig.4].

[0130] According to a preferred embodiment, the device according to the invention is characterized in that the cell comprises a nanoporous sensor support and a housing of parallelepiped shape, preferably cubic, comprising 4 lateral faces and a front face forming in its center a housing for receiving the nanoporous sensor support,

[0131] two opposite side faces presenting the gas inlet and outlet,

[0132] two opposite side faces presenting the optical input and output,

[0133] the front face having an opening for the insertion of the nanoporous sensor support into its housing ([Fig.6]).

[0134] The cell of the device according to the invention can thus comprise two elements.

[0135] The first element is its body which can consist of a square block ([Fig.6]) of brass reinforced for example by an internal layer of stainless steel, and which can in particular be hollowed out in its center and pierced on both sides on its four faces. Two tunnels per Pendiculars can thus be created to serve as passages for the gas flow and the probe light. This block can thus be equipped with an optical inlet and outlet as well as a gas inlet and outlet.

[0136] The second element can be a removable part, for example made of stainless steel ([Fig.6]) and which can also be pierced on the four faces for the passage of the gas flow and the light. The sealing of the 2 tunnels between the external block and the removable part can be achieved using O-rings. The removable part can contain in its center the nanoporous sensor, which can be for example a transparent monolithic block with maximum dimensions of the order of ten millimeters, for example 11 x 6.5 x 2 mm. The optical input and output can each include a lens to collimate the analysis light beam. The optical input can be connected by an optical fiber to a UV or Visible light source or a combination of the two UV-visible, and the optical output can be connected to the UV or visible or UV-visible spectrophotometer, necessary for the analysis and compatible with the lamp, via a second optical fiber.

[0137] An example of a cell of the device according to the invention is shown in [Fig.6].

[0138] The sensor can be exposed to the gas flow over its entire length and on both sides. The The probe light beam, coming from the light source and carried by an optical fiber, arrives perpendicular to the gas flow and is focused at the fiber outlet onto the sensor. The probed surface can be a circle of 5.7 mm2 (2.7 mm in diameter). The optical analysis path, which can vary from 1 to 2 mm, corresponds to the thickness of the inserted nanoporous sensor.

[0139] Depending on the geometry of the sensor, for example a disc or a parallelepiped, the removable part can be designed for good positioning of the sensor and its exposure to the gas flow over its largest surface.

[0140] According to a preferred embodiment, the sensor is placed between two half-cylinders, hollowed out to promote the passage of the gas flow above and below the sensor ([Fig.5] and [Fig.6]). The sensor is positioned at the intersection of a vertical hole which allows the probe light to pass through.

[0141] According to a preferred embodiment, the device according to the invention is characterized in that the nanoporous sensor support comprises two diametrically opposite passage orifices optically connected to the optical input and output.

[0142] Advantageously, the device according to the invention further comprises a computer and a battery to provide an electrical power supply to said device and thus make the device energy autonomous.

[0143] The device according to the invention may also comprise a screen allowing the user to interact with the elements of the system by computer.

[0144] The device according to the invention may also comprise a power supply card and energy control.

[0145] The elements of the device composed of the fluidic circuit and the optical analysis part can thus be positioned in a compartment of a portable element. This portable element could then comprise a second compartment containing a computer adapted to control the measurements and a third compartment comprising an electrical power supply to operate the device as a whole.

[0146] Thus, according to a particular embodiment, the device according to the invention can be integrated into a case comprising several levels, in particular 3 levels. The computer can for example be located on the upper level of the case, the device according to the invention on the intermediate level and the power supply on the lower level.

[0147] According to a preferred embodiment, the device according to the invention is characterized in that it is portable.

[0148] Advantageously, the device according to the invention allows the quantification of the said amine-type compound(s) in the gaseous sample to be analyzed. Examples

[0149] Example 1: Synthesis of nanoporous sensors according to the invention. Reagents used:

[0150] Tetramethylorthosilicate (TMOS), purity 99%, CAS: 681-84-5, Molar mass = 152.22 g-mol1 and density d = 1.023 g.cm 3

[0151] 4-(Dimethylamino)cinnamaldehyde (DMACA), purity >98%, CAS: 6203-18-5, Molar mass = 175.23 g-mol1

[0152] Polystyrene sulfonic acid (PSS), 30% aqueous solution, CAS: 28210-41-5, Molar mass

[0153] = 75,000 g-mol1 and density d = 1.1 g.cm 3

[0154] Paratoluenesulfonic acid (C^H7-SO H), purity >98%, CAS: 6192-52-5, Molar mass = 190.22 g-mol1

[0155] Ultra-pure deionized water.

[0156] Example 1.1: Hyl Sensor

[0157] In a 1 L bottle are mixed 14.2 mg of DMACA, 40.969 mL of H2O and 84.598 mL of TMOS. The solution is kept stirring at room temperature and 0.449 mL of 30% PSS is added dropwise, because the dissolution of PSS in the mixture is exothermic. The molar ratio of the silylated precursor and water in the mixture is TMOS / H2O = 1 / 4. The respective final concentrations of DMACA and PSS are 6.25 x 10 4 M and 1.18 g-L1 or [H+] ~ 6.25 x 103 M.

[0158] The sol is kept stirring for 24 hours at room temperature and then poured into a polypropylene mold containing 350 wells of 0.3 cm3 volume. The mold is placed in a 10L desiccator maintained at a relative humidity of 100% until Sol gelation. This step lasts 2 days at 22°C for Hy 1. The drying of the gels is then carried out by sweeping the desiccator with a humid Ar flow at 300 mL-min *. The relative humidity of the Ar flow, initially 100%, is decreased in stages to 80, 50 and then 0%. The drying time takes approximately 1 month at 22°C, during which the humidity in the desiccator decreases to reach 25% to 28% relative humidity. The mold is then removed from the desiccator. After demolding, parallelepiped-shaped sensors with dimensions of 9.6(H)*6.0(L)*l.26(thickness) mm are obtained for an initial solution of 0.3 mL. The final volume of the sensors obtained has shrunk by a factor of 4.2. The sensors are kept cool at 6°C, away from light. Example 1.2: Hy2 Sensor

[0159] Same procedure as Hyl with 14.2 mg of DMACA, 84.598 mL of TMOS, 40.969 mL of deionized H2O and 0.673 mL of 30% PSS. The molar ratio of the silylated precursor and water in the mixture is TMOS / H2O = 1 / 4. The respective final concentrations of DMACA and PSS are 6.25 x 10 4 M and 1.77 gL 1 or [H+ ] ~ 9.38 x 103 M. The gelation time of the sensors in the desiccator maintained at RH=100% is 2 days at 22°C. The drying time in steps from RH= 80, 50 to 0% takes about 40 days at 22°C, during which the humidity in the desiccator decreases to 25% to 28% relative humidity. After demolding, sensors with dimensions of 9.7(H)*6.l(W)*l.26(thickness) mm are obtained with a shrinkage factor of 4. The sensors are kept cool at 6°C, protected from light. Example 1.3: Hy3 Sensor

[0160] Same procedure as Hyl with 28.5 mg of DMACA, 84.598 mL of TMOS, 40.969 mL of deionized H2O and 0.898 mL of 30% PSS. The molar ratio of the silylated precursor and water in the mixture is TMOS / H2O = 1 / 4. The respective final concentrations of DMACA and PSS are 1.25 x 103 M and 2.34 gL 1 or [H+ ] ~ 1.25 x 102 M. The gelation time of the sensors in the desiccator maintained at RH=100% is 2 days at 22°C. The drying time in steps from RH= 80, 50 to 0% takes about 1 month at 22°C, during which the humidity in the desiccator decreases to 25% to 28% relative humidity. After demolding, sensors with dimensions of 9.5(H)*6.l(W)*l.24(thickness) mm are obtained with a shrinkage factor of 4.2. The sensors are kept cool at 6°C, protected from light. Example 1.4: Hy4 sensor

[0161] Same procedure as Hyl with 113 mg of DMACA, 81.496 mL of H2O and 43.91 mL of TMOS and 3.563 mL of 30% PSS. The molar ratio of the mixture of the silylated precursor and water is TMOS / H2O = 1 / 16. The final concentrations res The concentrations of DMACA and PSS are 5 x 103 M and 9.2 gL 1, i.e. [H+] ~ 5 x 102 M. The gelation of the sensors in the desiccator maintained at RH=100% takes place after 5 days at 22°C. The drying time in stages from RH= 80, 50 to 0% takes about 1.5 months at 22°C, during which the humidity in the desiccator decreases to 25% to 28% relative humidity. After demolding, sensors with dimensions of 8.37(H)*4.94(L)*l.03(thickness) mm are obtained with a shrinkage factor of 7. The sensors are kept cool at 6°C, away from light. Example 1.5: Hy5 Sensor

[0162] Same procedure as Hyl with 87.9 mg of DMACA, 33.777 mL of TMOS, 13.587 mL of H2O and 2.77 mL of 30% PSS. The molar ratio of the silylated precursor and water in the mixture is TMOS / H2O = 1 / 4. The respective final concentrations of DMACA and PSS are 1 x 102 M and 18.4 gL 1 or [H+] ~ 1 x 10 1 M. The gelation time of the sensors in the desiccator maintained at RH=100% is 5 days at 22°C. The drying time in steps from RH= 80, 50 to 0% takes about 1 month at 22°C, during which the humidity in the desiccator decreases to 25% to 28% relative humidity. After demolding, sensors with dimensions of 10.2(H)*6.4(L)*l.3(thickness) mm are obtained with a shrinkage factor of 3.5. The sensors are kept cool at 6°C, protected from light. Example 1.6: Hy6 Sensor

[0163] Same procedure as Hyl, with 226 mg of DMACA, 43.91 mL of TMOS, 77.933 mL of water and 7.126 mL of PSS. The molar ratio of the silylated precursor and water in the mixture is TMOS / H2O = 1 / 16. The final concentrations of DMACA and PSS are 1 x 102M and 18.4 gL 1 or [H+] ~ 1 x 10 1 M. The gelation time of the sensors in the desiccator maintained at RH=100% is 3 days at 22°C. The duration of drying in steps from RH= 80, 50 to 0% takes about 49 days at 22°C, during which the humidity in the desiccator decreases to reach 25% to 28% relative humidity. After demolding, sensors with dimensions of 8.4(H)*5.0(L)*l.05(thickness) mm are obtained with a shrinkage factor of 6.7. Example 1.7: Hy7 Sensor

[0164] In a 1 L bottle are mixed 56.5 mg of DMACA, 21.258 mL of H2O and 10.974 mL of TMOS. The solution is kept stirring at room temperature while slowly adding 613 mg of paratoluenesulfonic acid, C^H7-SO3H. When the acid is added to this mixture, it releases heat. The molar ratio of the silylated precursor and water is TMOS / H2O = 1 / 16. The respective final concentrations of DMACA and paratoluenesulfonic acid are 1 x 102M and 1 x 10'M.

[0165] The sol is kept stirring for 3 hours at room temperature and then poured in a polypropylene mold. The mold is placed in a 10L desiccator maintained at 100% relative humidity until the Sol gels. This step lasts 5 days at 22°C. Drying is carried out by sweeping the desiccator with an Ar flow of 300 mL-min *, gradually decreasing the relative humidity in the desiccator from 100% to 80%, 50% and then 0% RH. The drying time takes about 1 month at 22°C, during which the humidity in the desiccator decreases until it reaches 25% to 28% relative humidity. The mold is removed from the desiccator. After demolding, parallelepiped-shaped sensors with dimensions of 7.57(H)*4.8(L)*l.0(thickness) mm are obtained with a shrinkage factor of 8.2. The sensors are kept cool at 6°C, away from light. Example 1.8: Hy8 sensor

[0166] Same procedure as Hyl with 1.139 g of DMACA, 84.598 mL of TMOS, 5.054 and 35.916 mL PSS 30%. The respective final concentrations of DMACA and PSS are 5 x 102 M and 95.2 gL 1 or [H+] ~ 5 x 10 1M. The gelation time of the sensors in the desiccator maintained at RH=100% is 4 days at 22°C. The drying time in stages from RH= 80, 50 to 0% takes about 1 month at 22°C, during which the humidity in the desiccator decreases to reach 25% to 28% relative humidity. After demolding, we obtain sensors with dimensions 11.2(H)*6.4(L)*1.2(thickness) mm with a shrinkage factor of 3.4. Example 1.9: Hy9 sensor

[0167] Same procedure as Hyl with 596.5 mg of DMACA, 84.598 mL of TMOS, 23.012 mL of water and 17.958 mL of 30% PSS. The molar ratio of the silylated precursor and water is TMOS / H2O = 1 / 4. The respective final concentrations of DMACA and PSS are 2.5 x 102 M and 47.6 gL 1 or [H+] ~ 2.5 x 10 1 M. The gelation time of the sensors in the desiccator maintained at RH=100% is 2 days at 22°C. The drying time in steps from RH= 80, 50 to 0% takes about 1 month at 22°C, during which the humidity in the desiccator decreases to 25% to 28% relative humidity. After demolding, sensors with dimensions of 10.24(H)*6.5(L)*l.25(thickness) mm are obtained with a shrinkage factor of 3.6.

[0168] The porosity properties of nanoporous sensors such as the specific adsorption surface area, the pore volume or the size distributions of micropores and mesopores were determined from the establishment of N2 adsorption-desorption isotherms at the temperature of liquid N2. The table below groups these data.

[0169] [Tables 1] Sensor Formulation (TMOS / H2O) Concentration of reactants in soil (mol.L-1) ^solid Porosity properties [DMA CA] [PSS monomer] = [H+] [H*] [DMACA] Sdft / nP.g1 V / ' pore7 cm3.g -i % of por e Size in k % of mesopo re Size in k Hyl 1 / 4 in moles 6.25 x 104 6.25 x 10 3 10 4.2 1794 0.33 100% 5< d <19 0% Hy2 1 / 4 in moles 6.25 x 104 9.38 x 10 3 15 4.0 1929 0.44 95% 5< d <20 5% 20< d <88 Hy3 1 / 4 in moles 1.25 x 103 1.25 x 10 2 10 4.2 1878 0.4 97% 5< d <20 3% 20< d <65 Hy4 1 / 16 in moles 5 x 103 5 x 102 10 7.0 1478 0.51 82% 5< d <12 18% 20< d <131 Hy5 1 / 4 in moles 1 x 102 1 x 10 1 10 3.5 1593 0.42 90% 5< d <20 10% 20< d <102 Hy6 1 / 16 in moles 1 x 102 1 x 10 1 10 6.7 1414 0.42 86% 5< d <20 14% 20< d <88 Hy7 1 / 16 in mole 1 x 102 1 x 10 1 (C7H7-SO 3H) 10 8.2 853 0.24 88% 6< d <20 12% 20< d <61 Hy8 1 / 4 in mole 5 x 102 5 x 10 1 10 3.4 1778 0.52 89% 8< d <13 11% 20< d <131 Hy9 1 / 4 in mole 2.5 x 10 -2 2.5 x 10 1 10 3.6 1608 0.49 87% 5< d <20 13% 20< d <107

[0170] The percentages of micropores and mesopores given here correspond to the distribution of the adsorption surface as a function of the pore diameter. This percentage would be different if we consider the distribution of the pore volume as a function of the pore diameter. Example 2: Hyl sensor response to NH3

[0171] The Hyl sensor was exposed to a humid gas mixture (Relative Humidity Rate RH = 50%) containing 5 ppm of NH3. NH3 does not react with DMACA(H+) but induces deprotonation of DMACA(H+) to form neutral DMACA. In the porous material, neutral DMACA exhibits a broad absorption band in the UV-near-visible region with the maximum centered at 420 nm ([Fig.7]). The calibration curve of the Hyl sensor corresponding to the rate of formation of neutral DMACA as a function of NH3 concentration is shown in [Fig.7].

[0172] Example 3: Hy3 sensor response to N2H4. Establishment of a calibration curve of gaseous N2H4

[0173] The Hy3 sensors are exposed to different concentrations of N2H4 in a wide concentration range from 1 to 114 ppb. The relative humidity of the gas mixtures was kept fixed at 50%. For each exposure to a given N2H4 content, the formation rate of the 1DMACA-N2H4 complex at 388 nm was deduced. By plotting the formation rate of the 1DMACA-N2H4 complex as a function of the N2H4 concentration, a calibration curve for the detection of N2H4 at 388 nm is obtained. An example of an N2H4 calibration curve established for the Hy3 sensor is given in [Fig.8],

[0174] [Fig.8] shows the N2H4 calibration curve produced by exposing the Hy3 sensors with storage times varying from five months to fifteen months. A linear variation in the formation rates of the 1DMACA-N2H4 complex is obtained as a function of the N2H4 concentration. The detection limit is 1 ppb for a probed gas volume of 12L (60 minutes, 200 mL-min 1 and AAbs = 0.02). The exposure time can be reduced by increasing the flow rate of the gas mixture to be analyzed.

[0175] Example 4: Response of Hy3 sensors to N2H4, at different relative humidities

[0176] The effect of the relative humidity of the gas mixtures on the calibration curve of N2H4 of the Hy3 sensor is studied ([Fig.9]). For this purpose, the Hy3 sensors are exposed to different concentrations of N2H4 in gas mixtures at 30, 50 and 80% RH.

[0177] Example 5: Response of the Hy3 sensor to N2H4 in the presence of a potential interferent, NH2EtOH

[0178] The response of the Hy3 sensor to N2H4 in the presence of NH2EtOH is studied ([Fig. 10]). For this purpose, the Hy3 sensors are exposed to gas mixtures containing N2H4 + NH2 EtOH.

[0179] Example 6: Response of the Hy3 sensor to N2H4 in the presence of a potential interferent, morpholine

[0180] The response of the Hy3 sensor to N2H4 in the presence of morpholine is studied ([Fig. 11]). For this purpose, the Hy3 sensors are exposed to gas mixtures containing N2H4 + morpholine.

[0181] Example 7: Response of the Hy3 sensor to N2H4 in the presence of a potential interferent, NH3

[0182] The response of the Hy3 sensor to N2H4 in the presence of NH3 is studied ([Fig.12]). For this purpose, the Hy3 sensors are exposed to gas mixtures containing N2H4 + NH3.

[0183] Example 8: Response of the Hy3 sensor to N2H4 in the presence of the two potential interferents, NH3 and NH2EtOH

[0184] The response of the Hy3 sensor to N2H4 in the presence of the two potential interferents, NH3 and NH2EtOH, is studied ([Fig. 13]). For this purpose, the Hy3 sensors are exposed to gas mixtures containing N2H4 + NH3 + NH2EtOH.

[0185] Example 9: Response of the Hy3 sensor to N2H4 in the presence of two potential interferents, NH3 and morpholine

[0186] The response of the Hy3 sensor to N2H4 in the presence of the interferents, NH3 and morpholine, is studied ([Fig. 14]). For this purpose, the Hy3 sensors are exposed to gas mixtures containing N2H4 + NH3 + morpholine.

[0187] Example 10: Comparison of the responses of sensors Hyl, Hy2 and Hy3 to 30 ppb of N2H4

[0188] The responses of the sensors Hyl, Hy2 and Hy3 to N2H4 are studied ([Fig. 15]). For this purpose, the sensors Hyl, Hy2 and Hy3 are exposed to 30 ppb of N2H4.

[0189] Example 11: Comparison of Hy8 and Hy9 sensors at 40 ppb of N2H4

[0190] The responses of the Hy8 and Hy9 sensors to N2H4 are studied ([Fig. 16]). For this purpose, the Hy8 and Hy9 sensors are exposed to 40 ppb of N2H4.

[0191] Example 12: Comparison of sensors Hy4, Hy5, Hy6 and Hy7 at 25 ppb of N2H4

[0192] The responses of the sensors Hy4, Hy5, Hy6 and Hy7 to N2H4 are studied ([Fig. 17]). A For this purpose, sensors Hy4, Hy5, Hy6 and Hy7 are exposed to 25 ppb of N2H4. List of cited documents

[0193] [1] Toxicological data sheet no. 21 INRS http: / / www.inrs.fr / publications / bdd / fichetox / fiche.html?refINRS=FICHETOX_21

[0194] [2] Air quality. Workplace air. Sampling and analysis of gold vapors organic. Sampling by pumping on adsorption tube and solvent desorption. Standard NF X 43-267. La Plaine Saint Denis: AFNOR; 2004.

[0195] [3] Metropolitan Hydrazine M-7 sheet, http: / / www.inrs. fr / publications / bdd / metropol / fiche.html?refINRS=METROPOL_7

[0196] [4] Hydrazine. Method 108 In: Sampling and Analytical methods. OSHA, 1997 (https: / / www.osha.gov / dts / sltc / methods / organic / orgl08 / orgl08.html)

[0197] [5] B. J. Meneghelli, A review of hydrazine sensors: The State ofthe art, ASRC Aerospace Corp., Cocoa Beach, FL, United States, 2004.

[0198] [6] K. P. Brenner, S. L. Rose-Pehrss on, Performance Evaluation ofa Colorimétrie Hydrazine Dosimeter, 1994.

[0199] [7] https: / / dodtec.com / hydrazine-mmh-dose-estimator.html

[0200] [8] https: / / www.chemsee.com / commercial / toxic-gas / available-products / dosimeters / hyd-00 9-dosimeter-for-hydrazine /

[0201] [9] Rose-Pehrsson et al., brevet US005719061A

[0202] [1°] http: / / catalog.gasdetection.com / item / search-by-gas-type-hydrazine-s- / nalyzer-4000-ser ies-with-digital-display-hydrazine / 4180-100b

[0203] [1 *] https: / / www.raefrance.fr / produit / detecteur-cov-capteur-pid-ppbrae-3000 /

[0204] [l2] https: / / www.cbmetechindex.eom / p / 3525 / Smiths-Detection-Inc / Sabre-4000

[0205] [l3] https: / / www.environics.fi / product / chemprolOOi /

[0206] [l4] https: / / www.masatech.eu / portable-advanced-ion-mobility-spectrometer

[0207] [l5] https: / / www.smithsdetection.com / products / lcd-3-3 / Non-patent literature

[0208] For all useful purposes, the following non-patent element(s) is (are) cited: - nplcitl: MATHELY Paul, “The new French law on patents”; Librairie du Journal des notaires et des avocats, 1992, 660 p. (ISBN: 2850280372, 9782850280375); - nplcit2: www.inpi.fr; - nplcit3: www.epo.org; and - nplcit4: www.wipo.int.

Claims

Claims

1. A nanoporous sensor composed of a silicate sol-gel matrix containing a reagent composition, said reagent composition comprising a mixture of 4-(dimethylamino)-cinnamaldehyde and polystyrene sulfonic acid.

2. Nanoporous sensor according to claim 1, characterized in that it has a specific adsorption surface area of ​​700 to 2500 m2.g *, preferably of 800 to 2000 m2.g *.

3. Nanoporous sensor according to claim 1 or 2, characterized in that it has a pore volume of 0.1 to 0.9 cm3.g ', preferably of 0.2 to 0.8 cm3.g ', even more preferably of 0.2 to 0.6 cm3.g

4. Nanoporous sensor according to one of claims 1 to 3, characterized in that it has a proportion of micropores greater than 75%, preferably greater than 80%, more preferably ranging from 85% to 95%, the remainder to 100% corresponding to the proportion of mesopores.

5. A method for preparing a nanoporous sensor according to one of claims 1 to 4, said method comprising the following steps: a. Synthesis of a sol from an organosilylated precursor, the synthesis being carried out in a solvent, said solvent comprising water, in the presence of 4-(dimethylamino)-cinnamaldehyde and polystyrene sulfonic acid; b. Molding of the sol obtained in step a), followed by its gelling so as to obtain a gel; c. Drying of the gel obtained in step b), followed by its demolding so as to obtain a nanoporous sensor.

6. Method according to claim 5, characterized in that the organosilylated precursor is chosen from tetramethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxy silane, (3-(methylamino)propyl)trimethoxysilane, 3-carboxypropyltriethoxysilane, 3-carboxypropyltrimethoxysilane, tetraethoxysilane and their mixture.

7. Method for detecting in a gaseous sample to be analyzed at least one amine-type compound, said compound being chosen from hydrazine, ethanolamine, ammonia and morpholine, using a nanoporous sensor according to one of claims 1 to 4, said method comprising the steps of: a. bringing said gaseous sample to be analyzed into contact with said nanoporous sensor, b. detecting on said nanoporous sensor said amine-type compound(s) in the gaseous sample to be analyzed.

8. Method according to claim 7, for which step b) further comprises the quantification on said nanoporous sensor of said amine-type compound(s) in the gaseous sample to be analyzed.

9. Use of a nanoporous sensor according to one of claims 1 to 4, for the detection, or the quantification or the detection and quantification of at least one amine-type compound, said compound being chosen from hydrazine, ethanolamine, ammonia and morpholine.

10. Device (1) for detecting in a gaseous sample to be analyzed at least one amine-type compound, said compound being chosen from hydrazine, ethanolamine, ammonia and morpholine, said device comprising: - a cell (11) containing a nanoporous sensor according to one of claims 1 to 4 and comprising: - a gas inlet (111); - a gas outlet (112); - an optical inlet (113); - an optical outlet (114).

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