RU2377558C2 - Device for detecting chemical substances in air, chemical sensor and method of making said sensor - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to indication and rapid analysis of different substances in air, including poisonous substances, chemically hazardous substances, highly toxic substances etc. The device for detecting chemical substances in air has a sensor unit with at least one chemical sensor which is made in form of piezoelectric resonator with an active coating based on a polymer with molecular prints and an analysis and indication unit. The polymer with molecular prints is obtained by using non-toxic or low-toxic structural analogues of the corresponding chemical substances as a template compound with possibility of sorption of the said chemical substance. The sensor unit is made with a comparison sensor in form of a piezoelectric resonator with a coating based on a polymer which is obtained without the template compound.

EFFECT: possibility of indication or rapid analysis of different substances in air, including toxic chemicals in real time, ie directly without additional equipment to generate an analytical signal.

7 cl, 5 dwg

Description

The invention relates to the field of indication and rapid analysis in the air of substances of various nature, including poisonous substances (OV), chemically hazardous substances (AHS), highly toxic substances (SDYaV), explosives (BB), narcotic substances and other chemicals in real time.

The invention can be applied in gas detectors, gas analyzers of stationary and portable type for the operational control of the air at potentially dangerous chemical objects, in places of mass crowds, on public transport, in the system of counteraction to chemical terrorism.

A device is known in which chemical sensors based on piezoresonators with an active coating made using molecular imprinting technology for determining a number of organophosphorus compounds in air are used [Murray George M. et al. Polymer based lanthanide luminescent sensors for the detection of organophosphorus compounds - Patent US 20050019218, January 27, 2005]. The principle of operation of the device is based on measuring the frequency drift of a piezoresonator with a highly selective polymer sorbent applied with an increase in the mass of the polymer coating as a result of sorption of the analyte. The sorbent used was obtained on the basis of polymers with molecular imprints (molecularly imprinted polymers, PMO) by molecular imprinting. The device has a pre-concentration unit.

To avoid the use of poisonous and toxic substances in the synthesis of polymers with molecular imprints when setting up the sorbent, the products of their hydrolysis were used as template compounds, i.e. To analyze sarin and soman directly, the poisonous substances had to be hydrolyzed beforehand.

To increase the reliability of the analytical signal, an optical spectrometer was additionally used in the device. A complex of a Eu ³⁺ ion exhibiting luminescent properties with methyl 3,5-divinylbenzoate was introduced into the polymer. During sorption, the amount of ligands in the Eu ³⁺ ion changed, which led to a change in the wavelength at which luminescence occurred. This change was recorded by an optical spectrometer.

The disadvantages of the sensors and the device itself include the inability to use sensors in devices for indicating toxic chemicals directly. Analysis of sarin and soman using such sensors is carried out indirectly by the products of the hydrolysis of toxic substances. Hydrolysis requires an additional unit in the device. The use of a luminescent method in the device, as a duplicate method for obtaining an analytical signal, also requires additional equipment. The introduction of additional equipment reduces the reliability of the device and increases its cost.

The technical result to which the invention is directed is to create a chemical sensor and a device based on it, having the ability to display and express analysis in air of various substances, including toxic chemicals in real time, i.e. directly, without the use of additional equipment to obtain an analytical signal.

This result is achieved in that in a device for determining chemicals in air containing a sensor unit with at least one chemical sensor made in the form of a piezoresonator with an active coating based on a polymer with molecular imprints, and an analysis and indication unit, a polymer with molecular imprints were obtained using non-toxic or low-toxic structural analogues of the corresponding chemical substance as a template compound with the possibility of sorption of the latter, and sensory The lock is made with a comparison sensor in the form of a piezoresonator with a coating based on a polymer obtained without a template compound.

The device may contain sensors coated on the basis of polymers with molecular fingerprints obtained using structural analogues of the corresponding toxic substances, accidentally chemically hazardous substances, highly active toxic substances, explosives, and narcotic substances as template compounds.

The device may be equipped with a pre-concentration unit.

To achieve a technical result in a chemical sensor containing a piezoresonator with an active coating based on polymers with molecular imprints, a polymer with molecular imprints was obtained using non-toxic or low-toxic structural analogues of the corresponding chemical substance as a template compound with the possibility of sorption of the latter.

The sensor can be performed using the method of dipping a piezoresonator, for example quartz, into the prepolymerization mixture or the method of applying the prepolymerization mixture with a microsyringe.

A method of manufacturing a chemical sensor consists in preparing a prepolymerization mixture consisting of a template compound, methacrylic acid, ethylene glycol dimethacrylate, azobisisobutyronitrile, benzene and acetonitrile in a quantitative ratio of 1: 4: 20: 0.2: 50: 50, and withstanding the prepolymerization mixture for days, the prepolymerization mixture is applied to a quartz piezoresonator, followed by drying for 10 ... 20 minutes in air, copolymerization is carried out under the influence of a UV lamp with a wavelength of 250 ... 370 nm at t temperature 15 ... 25 ° C for 3 ... 5 hours, rinse the piezoresonator with the obtained film in diethyl ether from 2 to 5 times for 20 ... 30 minutes, followed by drying in air.

The prepolymerization mixture can be applied by dipping the resonator into the prepolymerization mixture twice or using a microsyringe.

Thus, the creation of a chemical sensor for the analysis of toxic chemicals is directly achieved by using an active coating based on polymers with molecular imprints, configured to sorb toxic chemicals, but obtained using non-toxic or low-toxic structural analogues as template compounds, for example: bis-2- chloroethyl ether (analog of mustard gas), O-methyl O-isopropyl ether of methylphosphonic acid (analog of sarin) and O-ethyl O-2- (N, N-diisopropylamino) ethyl ether methyl Background acid (analog VX).

The invention is illustrated by drawings.

Figure 1 presents a block diagram of a device for indicating and express analysis of vapors of chemical substances in the air, using a chemical sensor based on a quartz piezoresonator with an active coating, made using molecular imprinting technology; figure 2 - spectrum of mustard gas obtained on a system of 4 sensors (10 MHz). The concentration of mustard vapor 5 · 10 ^-5 g / l. Figure 3 - spectrum of sarin, obtained on a system of 4 sensors (10 MHz). The concentration of sarin vapor 5 · 10 ^-5 g / l. Figure 4 - spectrum of sarin obtained on a system of 4 sensors (155 MHz). The concentration of sarin vapor is 5 · 10 ^-7 g / l. Figure 5 - sarin spectrum obtained on a system of 4 sensors (250 MHz). The concentration of sarin vapor is 5 · 10 ^-8 g / l.

The device consists of 4 functional parts: an analysis preparation unit, an analysis and indication unit, a power supply, and a housing.

The analysis preparation unit consists of a vacuum pump, a device for preliminary concentration, and a sensor unit with sensors based on piezoresonators with a polymer sorbent. The listed components are placed in a metal or plastic duct. A device for preconcentration, made on the basis of activated carbon or other similar material, can increase the sensitivity of the device by at least 10 times. The pre-concentration device and the sensor unit have a design that makes it easy to remove them from the unit. The device has the ability to work without a device for pre-concentration.

The analysis and indication unit consists of a high-frequency generator, a frequency meter, a mathematical processing device for the analytical signal, and an indication and signaling device. A high-frequency generator, a frequency meter, and a device for mathematical processing of the analytical signal are built on the basis of integrated circuits. Indication and signaling devices have the possibility of sound and light signaling in the presence of the analyte in the air, as well as a graphical color display for displaying the concentration of the analyte in graphical and alphanumeric forms.

The device for mathematical processing of the analytical signal identifies substances using a mathematical apparatus based on the theory of pattern recognition by analyzing the "spectra" of these substances.

The developed chemical sensor is a quartz piezoresonator, on which a polymer sorbent (polymer with molecular imprints), configured to selectively sorb toxic chemicals or other chemical compounds, is applied on both sides as a thin film. For this, prepolymerization mixtures are prepared based on the corresponding structural analogue of a toxic chemical, monomers, polymerization initiator and solvents. The prepolymerization mixture is applied to the piezoresonator by dipping or using a microsyringe, kept in air for 15 minutes, after which the copolymerization reaction is carried out at 20 ° C for 4 hours using a UV lamp with a wavelength of 250 ... 370 nm. At the end of the reaction, the piezoresonator with the film is washed for 30 minutes in two solvents and dried in air for a day.

The analytical signal of the sensor is a change in the operating frequency of the quartz piezoresonator as a result of sorption of the analyte by the polymer and a change in the mass of the polymer coating.

The polymer with molecular imprints obtained on the surface of the piezoresonator is configured to adsorb one chemical compound, however, it can also sorb other chemical compounds to a small extent. Therefore, to obtain a reliable analytical signal in the display and express analysis devices, it is necessary to introduce another additional chemical sensor with a polymer of comparison. The sorbent based on the comparison polymer is obtained in exactly the same way as the polymer with molecular imprints, but in the absence of a template compound. In this case, both chemical sensors will react equally to impurities, however, in the presence of an analyte, the greatest change in the operating frequency of the quartz piezoresonator is characteristic of a chemical sensor with an active coating based on a polymer with molecular imprints (Figs. 2, 3). Thus, the number of sensors in a device designed to analyze n substances is n + 1 sensors. The use of quartz piezoresonators with a frequency of 10 MHz allows the creation of chemical sensors with a sensitivity threshold of 10 ^-6 g / l. The use of piezoresonators with frequencies of 155 MHz and 250 MHz can reduce the sensitivity threshold to 10 ^-8 g / l and 10 ^-9 g / l, respectively, when the time of receipt of the analytical signal after 30 seconds (figure 4, 5).

Example 1

Obtaining a sorbent configured for mustard gas (sarin, VX) in the form of a film

Prepolymerization mixtures are prepared from 0.35 grams (4 mmol) of methacrylic acid, 3.95 grams (20 mmol) of ethylene glycol dimethacrylate, 0.03 grams (0.2 mmol) of azobisisobutyronitrile, 3.8 grams (50 mmol) of benzene, 2.1 gram (50 mmol) of acetonitrile and a template compound, depending on which toxic chemical the polymer is tuned to, in quantity:

- 0.14 grams (1 mmol) of bis-2-chloroethyl ether (the polymer is adjusted to mustard gas);

- 0.15 grams (1 mmol) of O-methyl O-isopropyl ether of methylphosphonic acid (the polymer is adjusted to sarin);

- 0.25 grams (1 mmol) of O-ethyl O-2- (N, N-diisopropylamino) -ethyl methylphosphonic acid ester (polymer is tuned to VX).

After preparation, the solutions can withstand at least 1 day. To obtain a coating on a quartz piezoresonator, the prepolymerization mixture is applied with a microsyringe to the quartz surface in such an amount that, after copolymerization, a film of the required thickness (0.1 ... 1 nm) is formed. The sample is placed under a UV lamp with a wavelength of 250 ... 370 nm and kept at a temperature of 20 ° C for 4 hours. At the end of the copolymerization reaction, the piezoresonator with the deposited film is placed in a glass with 50 ml of ethyl alcohol. After 30 minutes, the sample was transferred to a glass with 50 ml of diethyl ether for another 30 minutes. After washing, the film-coated piezoresonator is dried in air for 1 day.

Reagents and equipment used

Methacrylic acid Merck Cat. - No. 800181 for synthesis.

Ethylene glycol dimethacrylate Merck Cat. - No. 803598 for synthesis.

Azobisisobutyronitrile Merck Cat. - No. 801641 for synthesis.

Benzene Merck Cat. - No. 822258 for synthesis.

Acetonitrile Merck Cat. - No. 800015 for synthesis.

Methylphosphonic acid O-isopropyl ester twice distilled in vacuo

Bis-2-chloroethyl ether twice distilled in vacuum.

O-Ethyl O-2- (N, N-diisopropylamino) methylphosphonic acid ethyl ester twice distilled in vacuo.

Ethyl alcohol TU 19 P-39-69 purified by distillation.

Diethyl ether Merck Cat. - No. 822270 for synthesis.

Microsyringe per 1 μl of HAMILTON Microliter.

Claims (7)

1. A device for determining chemicals in air, comprising a sensor unit with at least one chemical sensor made in the form of a piezoresonator with an active coating based on a polymer with molecular imprints and an analysis and indication unit, characterized in that the polymer with molecular imprints obtained using non-toxic or low-toxic structural analogues of the corresponding chemical substance as a template compound with the possibility of sorption of the latter, and the sensor unit is made with sensor comparison rum in the form of a piezoresonator with a coating based on a polymer obtained without a template compound. 2. The device according to claim 1, characterized in that it contains sensors coated on the basis of polymers with molecular prints obtained using template analogues of structural analogs of the corresponding toxic substances, chemically hazardous substances, highly toxic substances, explosives, narcotic substances. 3. The device according to claim 1 or 2, characterized in that it is equipped with a pre-concentration unit. 4. A chemical sensor made in the form of a piezoresonator with an active coating based on a polymer with molecular imprints, obtained using non-toxic or low-toxic structural analogues of the corresponding chemical substance as a template compound with the possibility of sorption of the latter. 5. The sensor according to claim 4, characterized in that the piezoresonator is made of quartz. 6. The sensor according to claim 4 or 5, characterized in that it is made using the method of dipping the piezoresonator into the prepolymerization mixture or the method of applying the prepolymerization mixture with a microsyringe. 7. A method of manufacturing a chemical sensor, which consists in preparing a prepolymerization mixture consisting of a template compound, methacrylic acid, ethylene glycol dimethacrylate, azobisisobutyronitrile, benzene and acetonitrile in a quantitative ratio of 1: 4: 20: 0.2: 50: 50, and withstand prepolymerization the mixture during the day, a prepolymerization mixture is applied on each side of the quartz piezoresonator, followed by drying for 15 minutes in air, copolymerization is carried out under a UV lamp with a wavelength of 250-370 nm at a temperature of 20 ° C for 4 hours, rinse the piezoresonator with the obtained film in diethyl ether 2 times for 30 minutes, followed by drying in air.

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