COLORIMETRIC DETECTION DEVICE IN THE FORM OF A FOAM FOR THE DETECTION OF CHEMICAL COMPOUNDS

Abstract

The invention relates to a colorimetric detection device for detecting the presence of at least one chemical compound, which is in the form of a foam and consists of a dispersion of gas bubbles in a foaming aqueous solution comprising one or more different colored indicators, characterized in that the colored indicator or each of the colored indicators is encapsulated in solid particles, and in that each solid particle comprises only one colored indicator when the foaming aqueous solution comprises several colored indicators. The invention also relates to a method for preparing the device as described above. It also relates to a method for detecting the presence of at least one chemical compound by implementing said device. Applications: colorimetric detection of chemical compounds, toxic chemical warfare agents, or toxic industrial chemical compounds.

Description

Title of the invention: Colorimetric detection device in the form of a foam for the detection of chemical compounds technical field

[0001] The invention relates to the field of colorimetric detection of chemical compounds.

[0002] More specifically, the invention relates to a colorimetric detection device, in the form of a foam, for detecting the presence of chemical compounds.

[0003] It also relates to a method of preparing such a device and to a method of detecting the presence of chemical compounds likely to be present on a surface, by implementing said device.

[0004] The present invention can be applied to the detection of toxic compounds, such as toxic warfare compounds or toxic industrial chemical compounds (known by the abbreviation TIC). Prior art

[0005] It is known that certain organophosphate compounds exhibit proven toxicity to the human body. Indeed, these compounds can be involved in the mechanism of inhibition of serine proteases and, in particular, of acetylcholinesterase, which is involved in synaptic junctions and whose dysregulation of activity can prevent muscle relaxation and thus cause death by asphyxiation.

[0006] These compounds are notably used in the formulation of certain pesticides or chemical warfare agents (such as organophosphate compounds of the G series or the V series).

[0007] However, due to the high lethality of these compounds and their proliferation, it is important to have systems or devices available to detect them.

[0008] Systems have then been proposed to detect these toxic compounds that may be present on a surface, which consist either of eroding said surface and then analyzing the residue or of applying a heat treatment to said surface to cause the evaporation of the toxic compounds and then analyzing the gases thus emitted.

[0009] There is also a system, called the "Portable System for Sampling Persistent Products by Evaporation" (or S4PE), which combines erosion and heat treatment of the surface likely to be contaminated by one or more toxic compounds. and which allows the evaporation of these compounds, which are then detected by a device called "Portable Contamination Control Device" (AP2C).

[0010] However, with such systems it is necessary to probe the entire surface to locate the points of contamination, which increases the duration of the operation and the duration of exposure of operators to toxic compounds.

[0011] It has also been proposed in patent EP 2 069 522-B1 (hereinafter reference [1]) to use an aqueous solution to detect the presence of toxic compounds, such as organophosphate compounds, that may be present on a surface. The aqueous solution in reference [1] is applied (or sprayed) onto said surface via a spray. It comprises one or more enzymes and at least one indicator compound, which may be a colored indicator.

[0012] The detection of a toxic compound is based, in reference [1], on an enzymatic reaction since, for example, when the aqueous solution is sprayed on the surface and the latter is contaminated by a toxic compound, then the enzyme or enzymes present in the aqueous solution react with the toxic compound, causing a change in pH of this solution and, consequently, a change in color of the colored indicator and therefore a change in color of the aqueous solution.

[0013] However, the use of the aqueous solution as described in reference [1] does not allow for precise and localized detection of the contamination points of toxic compounds and does not allow for discrimination of these compounds either.

[0014] Moreover, such use does not allow prolonged contact between the aqueous solution and the toxic compound(s), especially when the surface likely to be contaminated is a vertical surface (such as a wall).

[0015] Moreover, when several colored indicators are used in such an aqueous solution, they are likely to interact with each other, which is undesirable in the context of colorimetric detection of chemical compounds.

[0016] In view of the foregoing, the inventors have set themselves the goal of providing new devices which do not have the aforementioned disadvantages and which allow for the precise and rapid detection and, where appropriate, discrimination of toxic chemical compounds which may be present on any type of surface. Description of the invention

[0017] This objective is achieved by the invention, which firstly provides a colorimetric detection device for detecting the presence of at least one chemical compound, which is in the form of a foam and consists of a dispersion of gas bubbles in a foaming aqueous solution comprising one or more different colored indicators, and which is characterized in that the colored indicator or each of the colored indicators are encapsulated in solid particles, and in that each solid particle comprises (or encapsulates) only one colored indicator, whereas the foaming aqueous solution comprises several colored indicators.

[0018] In the preceding and following text, it is specified that "foam" means a two-phase system comprising a gaseous phase (i.e., the dispersion of gas bubbles) and a liquid phase (i.e., the foaming aqueous solution). Such a foam is typically called "liquid foam".

[0019] Furthermore, a "color indicator" is understood to be a substance that takes on at least one characteristic color in the presence of a chemical compound; in other words, a substance that exhibits at least two colored states: one colored state existing when the substance is not in the presence of the chemical compound to be detected, and at least one other colored state when the substance is in the presence of the chemical compound to be detected. The colored indicator is then said to exhibit a color change.

[0020] Furthermore, the expression "different colored indicators" means that each colored indicator reacts to at least one different specific chemical compound.

[0021] The fact that each of these colored indicators is encapsulated in solid particles makes it possible to limit, or even avoid, the migration of these indicators in the foaming aqueous solution and, consequently, any interaction between them.

[0022] Also, within the framework of the present invention, it is possible to detect and discriminate different chemical compounds.

[0023] According to the invention, said solid particles are typically in a (co)polymer, crosslinked or not.

[0024] It is specified that by "(co)polymer" we mean both a homopolymer which is derived from a single monomer and which is therefore formed of a single repeating motif, and a copolymer which is derived from several (that is to say, two or more of two) different monomers and which is therefore formed of several different repeating motifs.

[0025] Such particles can be obtained by (co)polymerization of one or more monomers - this (co)polymerization can then be a (co)polymerization in bulk, in solution, in suspension, in dispersion or in emulsion, induced by heat or UV, in the presence or not of a polymerization initiator - or by solubilization / precipitation of one or more (co)polymers in a suitable solvent.

[0026] In the case where the solid particles are in a crosslinked (co)polymer, then this crosslinking can result in: - of a functionalization of the monomer(s) prior to (co)polymerization, in which case the (co)polymerization is accompanied by cross-linking; - functionalization of the monomer(s) after (co)polymerization, in which case (co)polymerization and crosslinking are carried out in two steps; or - in the case of a copolymer, a copolymerization of one or more monofunctional monomers and one or more multifunctional monomers.

[0027] Crosslinking makes it possible to limit as much as possible the migration of the colored indicator(s) in the foaming aqueous solution.

[0028] Advantageously, the monomer or monomers are chosen from among the acrylate monomers such as, for example, methyl methacrylate, trimethylolpropane triacrylate, dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate.

[0029] Preferably, the (co)polymer is a poly(methyl methacrylate) (or PMMA) crosslinked by trimethylolpropane triacrylate (or TMPTA).

[0030] Said solid particles are, preferably, microparticles, that is to say they have an average size between 0.1 qm and 100 pm and, even better, between 5 qm and 50 qm.

[0031] This average size can be determined by measurements in optical microscopy, for example using an optical microscope such as that marketed by Fisher Scientific, under the reference Fisherbrand™ AX-500.

[0032] In this regard, it is specified that "size" means the largest of the three dimensions of the microparticles.

[0033] Furthermore, it goes without saying that the coloured indicator(s) are chosen so that they exhibit at least one colour change in the presence of the chemical compound(s) to be detected and are chosen, preferably, from among those which are colourless and those which have an initial colour - i.e. before any exposure to one or more chemical compounds - of light colour, for example, in shades of pale yellow.

[0034] In particular, when several different colored indicators are used, they are advantageously chosen so that they exhibit at least one colorimetric change contrasting with each other, so as to be able to discriminate the chemical compounds.

[0035] Advantageously, as many different colored indicators are used as there are chemical compounds to be detected.

[0036] In accordance with the invention and depending on the chemical compound(s) to be detected, the colored indicator(s) can be chosen from among anthraquinone compounds, azo compounds, triarylmethane compounds, xanthenic compounds, indigo compounds, metal complexes, compounds comprising at least one stilbene group, coumarin compounds, compounds comprising at least one quinoline group, compounds comprising at least one cyanine group, compounds comprising at least one phthalocyanine group and compounds comprising at least one porphyrin group.

[0037] Examples of anthraquinone compounds may include 1,4-dihydroxyanthraquinone, 1-aminoanthraquinone, carminic acid, 1,5-diaminoanthraquinone, 1,2-diaminoanthraquinone, l,4-diamino-5-nitroanthraquinone, 1,4,5,8-tetraaminoanthraquinone (also called "Disperse Blue 1" in English), l-methylamino-4-(2-hydroxyethyl)aminoanthraquinone (also called "Disperse Blue 3" in English), l-amino-2-methylanthraquinone (also called "Disperse Orange 77" in English) and 1,4-7"A-(p-tolylamino)anthraquinone (also called "Solvent Green 3" in English).

[0038] By way of examples of azo compounds, mention may be made of 10-(2',4'-dinitrophenylazo)-9-phenanthrol, disodium 6-hydroxy-5-[(2-methoxy-5-methyl-4-sulfophenyl)azo]-2-naphthalenesulfonate (also called "Allura Red AC"), 4-dimethylaminoazobenzene (also called "Methyl Yellow"), 4-(2-carboxyphenylazo)-A,A-dipropylaniline (also called "Propyl Red"), 3-(diethylamino)-7-{(E)-[4-(dimethylamino)phenyl]diazenyl}-5-phenylphenazin-5-ium chloride (also called "Janus Green B"), A,A-dimethyl-4,4'-azodianiline, A-ethyl- l-((4-phenyldiazenyl)phenyl)diazenyl)naphthalene-2-amine (also known as "Sudan Red 7B"), amaranth, 4-[[3-[(2,4-diaminophenyl)diazenyl]phenyl]diazenyl]benzene-l,3-diamine dihydrochloride (also known as "Bismarck Brown Y"), disodium 4-hydroxy-3-[(4-sulfo-l-naphthalenyl)azo]-1-naphthalenesulfonate (also known as "Chromotrope FB"),benzidinediazo-bis-l-naphthylamine-4-sulfonic acid (also known as "Congo Red"), 2,2'-[4-(4-aminophenylazo)phenylimino]diethanol (also known as "Disperse Black 9"), 2,2'-[[4-[(4-nitrophenyl)azo]phenyl]imino]bisethanol (also known as "Disperse Red 19"), (4Z)-4-[(l-hydroxynaphthalene-2-yl-hydrazinylidene]-7-nitro-3-oxo Y-naphthalene-l-sulfonate sodium (also known as "Eriochrome Black T"), 4'-(4-(diethylamino)phenylazo)acetophenone, 4-[(E)-(4-nitrophenyl)diazenyl]-A-phenylaniline (also known as "Disperse Orange 7"), methyl orange (also known as "M ethylorange"), 4-(4-nitrophenylazo)aniline (also called "Disperse Orange 3" in English), 4-[4-(phenylazo)-l-naphthylazo]phenol (also called "Disperse Orange 13" in English), 3-[A-ethyl-4-(4-nitrophenylazo)phenylamino]propionitrile (also called "Disperse Orange 25" in English), 4-amino-5-hydroxy-3-(4-nitrophenylazo)-6-(phenylazo)naphthalene-2,Sodium 7-disulfonate (also known as "Naphthol Blue Black"), (2,2-dimethyl-1,3-dihydroperimidine-6-yl)-(4-phenylazo-1-naphthyl)diazene (also known as "Sudan Black B"), disodium 6-hydroxy-5-[(4-sulfonatophenyl)azo]naphthalene-2-sulfonate (also known as "Sunset Yellow FCF"), tartrazine, Evans blue, 4-[4-(phenylazo)phenylazo]-o-cresol (also known as "Disperse Yellow 7"), and 4'-nitro-4-dimethylaminoazobenzene.

[0039] Examples of triarylmethane compounds may include bromocresol green, aniline diammonium blue, bromophenol blue, m-cresol violet, cresol red, gentian violet (also called "Crystal Violet" in English), chlorophenol red, sodium salt of (4-(a-(p-(diethylamino)phenyl)-2,4-disulfobenzylidene)-2,5-cyclohexadien-l-ylidene)diethylammonium hydroxide (also called "Patent blue V sodium salt" in English), methyl blue, rosolic acid, pyrocatechol violet, brilliant green BS, pararosaniline base, fuchsin, thymol blue and 4-(dimethylamino)-a-[4-(dimethylamino)phenyl]-a-phenylbenzenemethanol.

[0040] Examples of xanthenic compounds may include [9-(2-carboxyphenyl)-6-diethylamino-3-xanthenylidene]-diethylammonium chloride (also called "Rhodamine 610"), rhodamine 6G possibly in the form of a perchlorate salt, rhodamine B, hydrated sulforhodamine 101, fluoresceinamine (in particular isomer I) and rhodamine 110 chloride.

[0041] Indigo may be mentioned as an example of indigoic compounds.

[0042] As examples of metal complexes, mention may be made of trisodium 5-nitroso-6-oxidonaphthalene-2-sulfonate complexed with iron(III) (also called "Naphthol Green B" in English).

[0043] As examples of compounds comprising at least one quinoline group, mention may be made of 2,4-bis[p-(dimethylamino)styryl]quinoline.

[0044] As examples of compounds comprising at least one stilbene group, mention may be made of the dye known under the English terminology "Fluorescent Brightener 28".

[0045] As examples of coumarin compounds, mention may be made of 7-amino-4-(trifluoromethyl)coumarin, 7-amino-4-methylcoumarin, 3-(2-A-methylbenzimidazolyl)-7-A,A-diethylaminocoumarin (also called "Coumarin 30" in English), 2,3,6,7-tetrahydro-10-(3-pyridyl)-1H,5H,1llH-[1]benzopyrano[6,7,8-11]quinolizine-11-one (also called "Coumarin 510" in English), 3-(2-Benzothiazolyl)-7-(diethylamino)coumarin (also called "Coumarin 6" in English).

[0046] As examples of compounds comprising a cyanine group, mention may be made of indocyanine green, of 5,5'-dichloro-ll-diphenylamino-3,3'-diethyl-10,12-ethylenethiaticarbocyanine perchlorate (also called "1R140").

[0047] As examples of compounds comprising a phthalocyanine group, mention may be made of iron(III) phthalocyanine chloride, iron(III) phthalocyanine-4,4',4”,4'”-tetrasulfonic acid and 1,2,3,4,8,9,10,11,15,16,17,18,22,23,24,25-hexadecafluoro-29H,31H-phthalocyanine.

[0048] Preferably, the foaming aqueous solution comprises a total of 0.1% to 8% by mass, preferably 0.9% to 4% by mass, of solid particles encapsulating a colored indicator, relative to the total mass of said solution.

[0049] Furthermore, in addition to this or these colored indicators, the foaming aqueous solution more specifically comprises: - water, - one or more surfactants, preferably from 0.05% to 1.5% by mass relative to the total mass of the foaming aqueous solution; and possibly - one or more gelling agents (or so-called viscosifying agents), preferably from 0.00% to 0.8% by mass relative to the total mass of the foaming aqueous solution.

[0050] In this regard, it is specified that, in what precedes and follows, the expressions "from ....to ...." and "between .... and ...." mean that the limits are included.

[0051] Furthermore, "surfactants" means organic foaming surfactants, that is to say, surfactants comprising a lipophilic (nonpolar) part and a hydrophilic (polar) part and having a hydrophilic / lipophilic balance (or HLB for "Hydrophilic-Lipophilic Balance" in English) between 3 and 8. The HLB value of such a surfactant can easily be obtained by the method as described by J. T. Davies (in "A quantitative kinetic theory of emulsion type I. Physical Chemistry of the emulsifying agent", Gas / Liquid and Liquid / Liquid Interfaces, Proceedings of 2nd International Congress Surface Activity 1957, 426-438, hereinafter reference [2]) and from the HLB tables for different chemical groups, available to those skilled in the art.

[0052] More particularly, the surfactant(s) are advantageously chosen from non-ionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants and surfactants of bolaform or gemini type structure, preferably non-ionic surfactants, anionic surfactants and cationic surfactants and, even better, non-ionic surfactants.

[0053] Nonionic (or neutral) surfactants are compounds whose surface-active properties, particularly hydrophilic properties, are provided by uncharged functional groups such as an alcohol, an ether, an ester, or an amide, and may contain heteroatoms such as nitrogen or oxygen. Due to the limited hydrophilic contribution of these functional groups, nonionic surfactants are most often polyfunctional.

[0054] Within the framework of the present invention, the non-ionic surfactants may in particular be selected from alkyl alkoxylates, fatty alcohol alkoxylates, fatty amine alkoxylates, fatty acid alkoxylates, alkoxylates oxoalcohols, alkylphenol alkoxylates, alkyl ethoxylates, fatty alcohol ethoxylates, fatty amine ethoxylates, fatty acid ethoxylates, oxoalcohol ethoxylates, alkylphenol ethoxylates such as octylphenol and nonylphenol ethoxylates, alcohols, α-diols, polyethoxylated and polypropoxylated alkylphenols having a carbon chain, for example, C8-C[8] and comprising 2 to 50 groups of ethylene oxides or propylene oxides, complex polymers of polyethylene and polypropylene oxides, ethylene and propylene oxide copolymers, block copolymers of polyethylene and polypropylene oxides such as triblock copolymers POEPOP-POE, ethylene and propylene oxide condensates on fatty alcohols, polyethoxylated fatty amides preferably having 2 to 30 moles of ethylene oxide, polyethoxylated ethers preferably having 2 to 30 moles of ethylene oxide, monoesters (monolaurate,monomyristate, monostearate, monopalmitate, monooleate, etc.) and polyesters of fatty acids and glycerol, polyglycerol fatty amides comprising, on average, 1 to 5 and, more particularly, 1.5 to 4 glycerol groups, oxyethylenated fatty acid esters of sorbitan preferably comprising 2 to 30 moles of ethylene oxide, monoesters (monolaurate, monomyristate, monostearate, monopalmitate, monooleate, etc.) and polyesters of fatty acids and sorbitan, polyoxyethylene sorbitan monoesters, fatty acid esters of sucrose, fatty acid esters of polyethylene glycol, alkyl polyglucosides, α-alkylglucamine derivatives, and amine oxides such as alkylamine oxides, for example, in C10-C14 and A-acylaminopropylmorpholine oxides, polyols and in particular glucose alkylates such as glucose hexanoate, glucoside-derived surfactants (sorbitol laurate) and polyols such as glycerol alcohol ethers,Alkanolamides and their mixtures.

[0055] In particular, non-ionic surfactants may be chosen from those described in international application WO 2004 / 008463, hereinafter referred to as [3], and in particular from those belonging to the families of alkylpolyglucosides or alkylpolyetherglucosides, derived from glucose and biodegradable, such as those marketed by BASF under the trade names Glucopon™ (Glucopon™ 215 for example) or by SEPPIC under the trade names Oramix™ (Oramix™ CG-110 for example).

[0056] Anionic surfactants, on the other hand, are surfactants whose hydrophilic part is negatively charged. They can be chosen from sulfuric acid esters, phosphoric acid esters, alkyl or aryl sulfonates, alkyl or aryl sulfates, alkyl or aryl phosphates, alkyl or aryl sulfosuccinates, and alkyl and aryl sarcosinates associated with a counter ion such as a ammonium ion, a quaternary ammonium such as tetraethylammonium or tetrabutylammonium and cations such as Na+, Li+, Ca2+, Mg2+, Zn2+ and K+.

[0057] More specifically, anionic surfactants can be selected from tetraethylammonium paratoluenesulfonate, sodium dodecyl sulfate (or SDS), sodium laurylsarcosinate (or sarcosyl), sodium palmitate, sodium stearate, sodium myristate, sodium di(2-ethylhexyl) sulfosuccinate, methylbenzene sulfonate and ethylbenzene sulfonate.

[0058] Cationic surfactants, for their part, typically have at least one hydrocarbon chain and a polar head, and their hydrophilic part is positively charged. They can be chosen from quaternary ammonium compounds comprising at least one C4-C22 aliphatic chain associated with an anionic counter-ion chosen in particular from boron derivatives such as tetrafluoroborate and halide ions such as F, Br, I or Cl.

[0059] More particularly, the cationic surfactants can be selected from tetrabutylammonium chloride, tetradecylammonium chloride, tetradecyltrimethylammonium bromide (TTAB), alkylpyridinium halides bearing an aliphatic chain and alkylammonium halides.

[0060] On the other hand, when the foaming aqueous solution includes one or more gelling agents, it is understood that their mass percentage in this solution is strictly greater than 0.00 and, in this case, said solution is called a "viscous foaming aqueous solution". Otherwise, the foaming aqueous solution is called a "non-viscous foaming aqueous solution", in which case the solid particles encapsulating a colored indicator stabilize the foam, that is to say, the drainage (or drying) of this foam is slowed down.

[0061] These gelling agents are advantageously biodegradable and pseudoplastic. Preferably, they are chosen from water-soluble polymers, hydrocolloids, heteropolysaccharides such as trisaccharide branched-chain polyglucosidic polymers, cellulosic derivatives and polysaccharides such as polysaccharides comprising glucose as the sole monomer.

[0062] More particularly, the gelling agent(s) usable within the framework of the present invention are chosen from xanthan gum, guar gum, agar-agar, carrageenan, sodium alginate, caseinate, gelatin, pectin, starch, cellulose, 2-hydroxyethylcellulose (HEC) and chitosan, preference being given to xanthan gum.

[0063] A foam usable within the scope of the invention can, for example, be obtained from a foaming aqueous solution comprising at least one of the colour indicators mentioned above and, more specifically, bromocresol green, Disperse Black 9 and / or 2,4-bis[p-(dimethylamino)styryl]quinoline, an alkyl polyglucoside and, possibly, xanthan gum.

[0064] It should be noted that the foaming aqueous solution can be neutral, acidic, or basic depending on the colored indicator(s) it contains and the pH conditions required for the proper functioning of said indicator(s). A person skilled in the art will be able to determine the most suitable pH for this solution.

[0065] In any event, due to the composition of the foaming aqueous solution, the foams constituting the device of the invention have the advantages of foams with controlled and increased lifetime and are suitable for being deposited on any type of surface (for example, vertical or horizontal) and for ensuring prolonged contact for a sufficient time to allow the colored indicator(s) to react, where appropriate, with the chemical compound(s) present on said surfaces and thus reveal the presence of these compounds.

[0066] In particular, for vertical surfaces, the foams slide slowly by gravity but stay on these surfaces long enough to allow the colored indicator(s) to react with the chemical compound(s) to be detected.

[0067] Furthermore, the present invention makes it possible to visually (i.e., with the naked eye), quickly and precisely locate the area(s) of contamination by the chemical compound(s), particularly thanks to colored indicators which have the advantage of not diffusing into the foam. In other words, when one or more chemical compounds are present on a surface, one or more color changes are observed within the foam, but only in the areas contaminated by the chemical compound(s), and no other color changes are observed in the rest of the foam. This will allow for better adaptation of any decontamination step following this detection.

[0068] This detection principle is shown in [Fig. 1] attached as an appendix with: - for part (a), the surface of a plate 1 on which a drop 3 of a chemical compound whose presence we wish to detect is deposited; - for part (b), the surface of said plate coated with a layer of foam 5 constituting the device of the invention and comprising one or more different colored indicators capable of detecting the chemical compound; and - for part (c), the surface of said plate coated by the foam layer 5 after reaction of the coloured indicator with the underlying drop of chemical compound, the colour change being only localised in the form of a coloured spot 7 located opposite the underlying drop of chemical compound.

[0069] Furthermore, due to the composition of the foaming aqueous solution, the foams constituting the device of the invention also have the advantage of generating very little waste since a small volume of liquid effluent will be produced (between 5% and 20% of liquid effluents compared to a "classic" liquid decontamination solution which will generate 100% liquid effluents).

[0070] Furthermore, the colorimetric detection device according to the invention is particularly suitable for the detection and, where appropriate, the discrimination of chemical compounds, whether liquid or solid.

[0071] According to the invention, these chemical compounds can be toxic compounds, such as toxic warfare compounds or toxic industrial chemical (TIC) compounds.

[0072] More specifically, toxic warfare compounds can be organophosphate compounds of the G series (such as sarin or soman), organophosphate compounds of the V series (such as compound VX), other organophosphate compounds, vesicant compounds (such as sulfur mustard gas, denoted HD, or lewisite, denoted Ll) and / or arsenic compounds.

[0073] Industrial toxic compounds, meanwhile, can be chlorine, ammonia, carbon disulfide, hydrogen cyanide, nitric acid, sulfuric acid and / or formaldehyde.

[0074] The invention also relates, secondly, to a method for preparing the device as defined above, comprising the following successive steps: a) a step of preparing the solid particles encapsulating a colored indicator; b) a step of preparing the foaming aqueous solution by mixing the solid particles obtained at the end of step a), with water, one or more surfactants and, optionally, one or more gelling agents; then c) a step of generating the foam from the foaming aqueous solution obtained at the end of step b).

[0075] It goes without saying that several different colored indicators can be used, in which case step a) is implemented several times for each of these colored indicators.

[0076] Furthermore, the solid particles, the colour indicator(s), the surfactant(s) and the gelling agent(s) are as described above.

[0077] According to the invention, the solid particles, water, the surfactant(s) and optionally the gelling agent(s) are mixed, in step b), so that the resulting foaming aqueous solution comprises: - from 0.1% to 8% by mass, preferably from 0.9% to 4% by mass, of solid particles encapsulating a colored indicator, relative to the total mass of said solution; - from 0.05% to 1.5% by mass of surfactant(s) relative to the total mass of said solution; and - from 0.00% to 0.8% by mass of gelling agent(s) relative to the total mass of said solution.

[0078] Step c) of the preparation process can be carried out by any foam-generating device described in the prior art and known to those skilled in the art. More particularly, this includes devices ensuring gas-liquid mixing, notably by mechanical agitation, by bubbling, by static mixer with or without beads, by microbead tube foam generator, by devices such as those described in international application WO 02 / 043847, hereinafter referred to as [4], or by any other device, in particular nozzle or venturi systems allowing high flow rates (generally between 1 and 1,000 m³ / h). The use of a foam generator is particularly advantageous because it limits the distance between the operator and the potentially contaminated surface.

[0079] The present invention also relates to the use of a device as previously defined to detect the presence of one or more chemical compounds likely to be present on a surface.

[0080] The invention therefore relates, thirdly, to a method for detecting the presence of at least one chemical compound on a surface likely to contain that compound, which method comprises the following successive steps: - a step of bringing the colorimetric detection device, as defined above, into contact with said surface; then - a step of deducing the presence of the chemical compound on said surface based on a possible colorimetric change.

[0081] According to the invention, the contact step can consist of applying the foam to the surface by spraying, in which case the foam is generated at the time of contact, or by troweling (i.e. spreading by layer), in which case the foam is generated prior to contact.

[0082] Preferably, the sprayed or spread foam has a thickness of between 0.5 cm and 5 cm and, even better, between 0.5 cm and 2 cm.

[0083] Between the contact step and the deduction step, a waiting period may be provided so that, if necessary, the color change(s) can take place.

[0084] For the deduction step, the operator may rely on a colorimetric scale associated with the colorimetric detection device which will define, for all chemical compounds likely to be detected by this device, the corresponding colorimetric change, this colorimetric scale being able to be determined by prior tests for each of the devices and for each of the chemical compounds intended to be detected.

[0085] The deduction can therefore be easily made with the naked eye upon observation of a change in colour.

[0086] Furthermore, the detection method according to the invention is applicable to any type of surface, regardless of its geometry. For example, said surface may be simple, such as a flat surface, or it may be complex, such as a rough surface or one with unobstructed cavities, and this regardless of the material constituting this surface.

[0087] According to the invention, the surface capable of comprising the chemical compound(s) to be detected can be made of a metal, such as aluminium, a metal alloy, such as steel, stainless steel or tinplate, silicon, glass generally comprising silicates, silica glass, ceramic, brick, porcelain, cement, concrete, asphalt, stone, granite, wood, earth, plastic or any combination thereof.

[0088] Furthermore, the surface likely to contain the chemical compound(s) to be detected can be of any size, shape, and orientation. It can be a large surface such as a road or wall, a ceiling and / or floor of a large infrastructure such as a building, hotel, airport, or public transportation system. It can also be an intermediate-sized surface such as the surfaces of industrial objects like a machine used in the food industry, a vehicle, an aircraft, a tank, a restaurant kitchen, a cold storage room, a sanitary facility, or a container. Alternatively, it can be a small surface such as the surfaces of medical devices or weapons.

[0089] According to the invention, the chemical compounds that can be detected by the process of the invention can be toxic compounds, such as toxic warfare compounds or so-called TIC compounds.

[0090] Toxic warfare compounds can be G series organophosphate compounds (such as sarin or soman), V series organophosphate compounds (such as compound VX), other organophosphate compounds, vesicant compounds (such as sulfur mustard gas, denoted HD, or lewisite, denoted Ll) and / or arsenic compounds.

[0091] Industrial toxic compounds, meanwhile, can be chlorine, ammonia, carbon disulfide, hydrogen cyanide, nitric acid, sulfuric acid or formaldehyde.

[0092] Furthermore, after the deduction step, an additional step consisting of recovering the foam or the residues of this foam can be implemented, for example, by vacuuming and / or wiping (in particular by means of a wipe or a sponge) after the foam has dried.

[0093] If some foam remains, i.e., before it has completely dried, this foam is recovered. However, if the liquid phase of the foam has completely evaporated—i.e., completely dried—only dry residues remain. are present on the surface that has been in contact with the foam and it is these residues that are recovered.

[0094] In the event that one or more color changes are observed (i.e. after deduction of the presence of one or more chemical compounds), a surface decontamination step can be easily and quickly implemented, in particular thanks to the discrimination of the chemical compound(s) detected.

[0095] Other features and advantages of the invention will become apparent from the following supplementary description.

[0096] It goes without saying that this additional description is given only as an illustration of the object of the invention and should in no way be interpreted as a limitation of this object. Brief description of the figures

[0097] [Fig. 1], already commented on, illustrates the general principle of detection according to the invention.

[0098] Detailed description of particular implementation methods

[0099] 1. Encapsulation of different colored indicators

[0100] 1.1 Encapsulation of bromocresol green in solid PMMA particles / TMPTA

[0101] The encapsulation of bromocresol green in PMMA / TMPTA particles (i.e., poly(methyl methacrylate) crosslinked with trimethylolpropane triacrylate) is carried out according to the following protocol: 1°) 5 mg of previously ground bromocresol green and 50 mg of Irgacure™ 819 photoinitiator (supplied by BASF with commercial reference 56415892) are suspended in 20 mL of cyclohexane and then passed through ultrasound; 2°) the suspension thus obtained is placed under magnetic stirring in a UV tank (supplied by Hônle, under the reference UVA-cubelOO; 365 nm; ~4 mW / cm2); 3°) still under stirring, a solution comprising 0.2 mL of MMA and 0.8 mL of TMPTA is introduced into the suspension using a syringe; 4°) the suspension obtained at the end of point 3°) is irradiated under UV for 4 minutes; it then changes from a transparent appearance to a milky appearance; 5°) Cyclohexane is then added to eliminate the residual photoinitiator; 6°) the suspension is then centrifuged at 10,000 rpm for 5 minutes, then the cyclohexane is removed and replaced with ethanol; 7°) the suspension is centrifuged again at 10,000 rpm for 5 minutes to remove, this time, the residual unencapsulated bromocresol green; and finally, 8°) the particles thus obtained in the suspension are recovered by filtration on a pleated filter, rinsed with water and dried at room temperature.

[0102] 1.2 Encapsulation of Disperse Black 9 in solid PMMA particles / TMPTA

[0103] The same protocol as that described in point 1.1 above is implemented, this time using Disperse Black 9 as a colour indicator, instead of bromocresol green.

[0104] 1.3 Encapsulation of 2,4-bis[p-(dimethylamino)styryl]quinoline in PMMA / TMPTA solid particles

[0105] The same protocol as that described in point 1.1 above is implemented, this time using 2,4-bis[p-(dimethylamino)styryl]quinoline as a colour indicator, instead of bromocresol green.

[0106] 2. Preparation of two different mousses (M1 and M2)

[0107] Two foams according to the invention are prepared: a first (foam M1) from a viscous aqueous foaming solution and a second (foam M2) from a non-viscous aqueous foaming solution. The qualitative and quantitative composition of the aqueous solutions from which foams M1 and M2 are prepared is shown in the following Table 1: [Table 1] Painting ! Surfactant, Gelling Agent, Color Indicators, Foam, Ml GlucoponTiw; 2QgA Xanthan Gum: 6 g / L, Encapsulated Bromocresol Green: 18 g / L; Encapsulated Disperse Black 9: 18 g / L, M2 Glucopon™ Foam: 14 g / L, Encapsulated Bromocresol Green: 18 g / L; Encapsulated Disperse Black 9: 18 g / L

[0108] The Glucopon™ used in the examples corresponds to that marketed by BASF, under the trade reference Glucopon™ 215 UP and the xanthan gum corresponds to that marketed by Sigma-Aldrich, under the trade reference Xanthane G1253.

[0109] Foams M1 and M2 are each prepared from: - 50% by volume of an aqueous solution of 65% nitric acid, having a pH of 3 and comprising the encapsulated color indicators in the quantities mentioned in Table I; the resulting solution is shaken to disperse the encapsulated color indicators; and - 50% by volume of a solution comprising Glucopon™ and, optionally, xanthan gum, according to the quantities mentioned in Table I.

[0110] The foaming aqueous solutions thus obtained are yellow in color and have a pH of 4. They are then agitated using a paddle until the foams M1 and M2 are obtained, which have a pale yellow color. [YES] 3. Use of M1 and M2 foams to detect compounds simulating toxic compounds on a horizontal surface

[0112] 3.1 Use of M1 and M2 foams for detecting DPCP

[0113] The M1 and M2 foams obtained in point 2 above are each spread in the form of a layer of approximately 5 mm on an aluminium support placed horizontally and on which drops of diphenylchlorophosphate (DPCP) have previously been deposited.

[0114] A color change was observed from 25 minutes (for M1) and 30 minutes (for M2) which intensified over time, until a violet color was obtained after 70 minutes (for M1) and 40 minutes (for M2), this color change being observed only at the locations where the underlying DPCP drops are located.

[0115] Furthermore, for the M2 foam, it was observed that it dries faster than the M1 foam and that, after one hour and 30 minutes, only particles are present on the aluminum support, these particles having a violet color at the locations where the underlying DPCP drops are located while the rest of the particles are colorless.

[0116] 3.2 Use of M1 and M2 foams to detect NaOH

[0117] The same test as in point 3.1 above was carried out but implementing this This time, aluminium supports on which drops of 0.1 mol / L NaOH have been previously deposited, instead of DPCP.

[0118] A color change was observed from 25 minutes (for M1) and 10 minutes (for M2) which intensified over time, until a blue / green color was obtained after 70 minutes (for M1) and 30 minutes (for M2), this color change being, again, localized only at the level of the places where the underlying NaOH drops are located.

[0119] 4. Use of M1 and M2 foams to detect simulating compounds toxic compounds on a vertical support

[0120] The M1 and M2 foams are respectively spread in the form of a layer of approximately 5 mm on aluminium supports comprising either drops of DPCP or drops of 0.1 mol / L NaOH, which supports are then placed under a fume hood and vertically.

[0121] The foams slide by gravity, but their specific drainage-retarding properties allow them to remain in contact with the DPCP and NaOH sufficiently It took a long time to observe a change in color, which therefore attests to the effectiveness of these foams even on a vertical surface.

[0122] 5. Use of Ml foam to detect NaOH in the form solid

[0123] An aluminum support containing drops of 0.1 mol / L NaOH is placed under a fume hood. When the NaOH deposit is dry, the Ml foam is applied in the same way as in the previous tests (see points 3 and 4).

[0124] After 25 minutes, a change in the color of the foam was observed at the level of the NaOH deposits, thus confirming the possibility of detecting chemical compounds, whether in liquid or solid form.

[0125] 6. Use of different foams to detect toxic compounds of war

[0126] In this test, four different foams (M3 to M6) are prepared from viscous foaming aqueous solutions according to the specific compositions in the following Table II: [Table 2] Table fl Surfactant Gelling agent Colour indicators M3 Glucopon™ Foam: 10 g / L Xanthan gum: 3 g / L Encapsulated bromocresol green: 37 g / L M4 Glucopon|M Foam: 10 g / L Xanthan gum: 3 g / L Encapsulated Disperse Black 9: 37 g / L M5 Glucopon™ Foam: 10 g / L Xanthan gum: 3 g / L Encapsulated 2,4-bis(pl) dimethyl lamino) s ty ryljqu ind éi ne: 37 g / L M6 Glucopon™ Foam: 10 g / L Xanthan gum: 3 g / L Green. encapsulated bromocresol: 12.3 g / L; encapsulated Disperse Black 9: 12.3 g / L; encapsulated 2,4-bisp-(d-methylamino)styrylqunoine: 12.3 g / L

[0127] In each of the foaming aqueous solutions, 1 mol / L sulfuric acid is added until a pH of 4 is obtained.

[0128] The foaming aqueous solutions are then agitated using a paddle until foams M3 to M6 are obtained, all of which have a pale yellow color.

[0129] Each foam is brought into contact with each of the following toxic warfare compounds: Soman, Compound VX, Compound HD and Compound LL

[0130] The observed color changes are shown in the following Table III: Table Hl Soman VX HD LL Mousse M3 - Blue - - Mousse M4 Darker Latin Orange Violet (slight tint) Violet Mousse M5 — — — Mousse M6 Orange Green Violet (slight tint) Violet

[0131] It follows that: - M3 foam allows detection of the VX compound; - M4 foam allows the detection of Soman, VX compound, HD compound, and L1 compound; and - M6 foam allows detection of Soman, compound VX, compound HD and compound Ll.

[0132] References cited [1] EP2 069 522-B1; [2] “A quantitative kinetic theory of emulsion type I. Physical Chemistry of the emulsifying agent”, Gas / Liquid and Liquid / Liquid Interfaces, Proceedings of 2nd International Congress Surface Activity 1957, 426-438 [3] WO-A-2004 / 008463 [4] WO-A-02 / 043847

Claims

Demands

1. A colorimetric detection device for detecting the presence of at least one chemical compound, which is in the form of a foam and consists of a dispersion of gas bubbles in a foaming aqueous solution comprising one or more different colored indicators, characterized in that the colored indicator or each of the colored indicators is encapsulated in solid particles, and in that each solid particle comprises only one colored indicator when the foaming aqueous solution comprises several colored indicators.

2. Device according to claim 1, wherein the solid particles are in a (co)polymer.

3. Device according to claim 2, wherein the (co)polymer is obtained from the (co)polymerization of at least one acrylate monomer such as methyl methacrylate, trimethylolpropane triacrylate, dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate.

4. Device according to claim 2, wherein the (co)polymer is a poly(methyl methacrylate) crosslinked with trimethylolpropane triacrylate

5. Device according to any one of claims 1 to 4, wherein the colour indicator(s) are selected from anthraquinone compounds, azo compounds, triarylmethane compounds, xanthenic compounds, indigo compounds, metal complexes, compounds comprising at least one quinoline group, compounds comprising at least one stilbene group, coumarin compounds, compounds comprising at least one cyanine group, compounds comprising at least one phthalocyanine group and compounds comprising at least one porphyrin group.

6. Device according to any one of claims 1 to 5, wherein the foaming aqueous solution comprises a total of 0.1% to 8% by mass, preferably 0.9% to 4% by mass, of solid particles encapsulating a colored indicator, relative to the total mass of said solution.

7. A device according to any one of claims 1 to 6, wherein the foaming aqueous solution comprises one or more surfactants and, possibly, one or more gelling agents.

8. Device according to claim 7, wherein the foaming aqueous solution comprises from 0.05% to 1.5% by mass of surfactant(s) and from 0.00% to 0.8% by mass of gelling agent(s) relative to the total mass of said solution.

9. Device according to claim 7 or claim 8, wherein the surfactant(s) are selected from non-ionic surfactants, anionic surfactants and cationic surfactants, preferably non-ionic surfactants.

10. Device according to any one of claims 7 to 9, wherein the gelling agent(s) are selected from water-soluble polymers, hydrocolloids, heteropolysaccharides, cellulosic derivatives and polysaccharides.

11. A method for preparing the device according to any one of claims 1 to 10, comprising the following successive steps: a) a step of preparing the solid particles encapsulating a colored indicator; b) a step of preparing the foaming aqueous solution by mixing the solid particles obtained at the end of step a) with water, one or more surfactants and, optionally, one or more gelling agents; then c) a step of generating the foam from the foaming aqueous solution obtained at the end of step b).

12. A method for detecting the presence of at least one chemical compound on a surface likely to contain that compound, comprising the following successive steps: - a step of bringing the device according to any one of claims 1 to 10 into contact with said surface; then - a step of deducing the presence of the chemical compound on said surface based on any color change.

13. A method according to claim 12, wherein the chemical compound(s) are toxic warfare compounds and / or toxic industrial compounds.

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