RU218361U9 - DEVICE FOR SELECTION AND SUBMISSION OF SAMPLES OF LABORLY SUBSTANCES FOR CHEMICAL ANALYSIS - Google Patents

Abstract

The utility model relates to analytical instrumentation, namely to devices for supplying samples of low-volatile substances for analysis, capable of passing into the vapor phase from solid materials under analysis conditions, in particular, for qualitative and quantitative trace analysis by gas chromatography and mass spectrometry methods.

Essence of the utility model: the claimed technical result is achieved by the fact that a removable sample carrier is used to transfer a sample containing low-volatile substances into the injection tube, and for its precise positioning in the injection tube, a fixation device is used that does not allow contact of the sample carrier with the inner tube. A sample containing non-volatile substances is transferred to the carrier as a result of contact with the surface of the object under study, mainly due to adhesion.

EFFECT: increased speed, reliability, as well as simplification of the analysis of impurities, traces of hardly volatile substances located on surfaces or inside solid materials.

Description

The utility model relates to analytical instrumentation, namely to devices for supplying samples of low-volatile substances for analysis, capable of passing into the vapor phase from solid materials under analysis conditions, in particular, for qualitative and quantitative trace analysis by gas chromatography and mass spectrometry methods.

Devices for submitting samples for analysis (input devices) are one of the most important elements of chemical analysis equipment based on gas chromatography and mass spectrometry methods. Their characteristics are especially important in the analysis of trace concentrations of reactive substances. In this case, to ensure the reliability of the analysis, it is necessary to submit the sample for analysis in the shortest way without intermediate contact of the sample components with the elements of the device and in the minimum time. When a sample is fed into a gas chromatographic column, a narrow peak is formed in this way and no additional focusing of the sample is required.

Determination of traces and microparticles of non-volatile substances on various surfaces is an important analytical task, focused primarily on the identification of prohibited and controlled substances, such as explosives and narcotic substances. In addition, such an analysis is in demand in the interests of ensuring the chemical safety of the population during biomonitoring in order to quickly determine toxic exogenous substances and their metabolites in human biological fluids, including the lipid layer of the skin. In the field of precision medicine, there is an increasing number of studies aimed at operational therapeutic monitoring, as well as the development of non-invasive methods for monitoring biomarkers in the lipid layer of human skin for early diagnosis of diseases.

Known device for the selection and input of volatile substances, described in the article by Huang, Min-Zong et al. Rapid characterization of chemical compounds in liquid and solid states using thermal desorption electrospray ionization mass spectrometry // Analytical chemistry. - 2013. - T. 85. - No. 19. - C. 8956-8963. The device includes a tube made of quartz with an inner diameter of 4 mm and a length of 80 mm, placed inside the heater, one open end of which is located near the ionization region of the ion source of the mass spectrometer, and the other open end has a removable plug, a branch pipe connected to the upper end of the tube through which carrier gas, a removable sample carrier, which is made in the form of a stainless steel needle with a diameter of 0.35 mm. To take a sample from the surface, the removable carrier is brought into contact with the surface and passed over it several times. Analytes transfer from the analyzed surface to the removable media as a result of adhesion. To submit the sample for analysis, the plug is removed and instead, the sample carrier is hermetically installed in the heated tube. The desorbed substances are directed by the carrier gas flow to the ion source of the mass spectrometer, which is at atmospheric pressure, through the open end of the tube. This device has a limited scope, since it is designed to work only with atmospheric pressure ionization sources (atmospheric pressure chemical ionization, electrospray, etc.). This device is not designed to supply a sample to a chromatographic column. While samples taken from real surfaces have a complex chemical composition and require prior chromatographic separation to ensure reliable analysis results.

A device for submitting samples for gas analysis is known, which is the closest to the claimed device in terms of technical essence (prototype) (Patent for invention No. 2126148, IPC G01N 30/04, 1/22, publ. 10.02.1999).

The device diagram is shown in Fig. 1. The device includes an inner tube 1 representing a quartz capillary column for gas chromatography, the end 2 of which is made open, and the other end is connected through a detector 3 to a gas flow driver (not shown in the diagram), which is a vacuum pump. The intermediate tube 4 has an open end 5, and a plug 6 is installed at its other end. The end 2 of the inner tube 1 is passed through the plug 6. The outer tube 7 has an open end 8, and its other end 9 is docked with the end 5 of the tube 4. Channel isolation unit The outer tube 7 from the external environment is made in the form of a carrier gas flow driver 10 connected by means of a pipe 11 to an intermediate pipe 4. The carrier gas flow driver 10 is a vessel with a carrier gas under pressure, equipped with a valve for regulating the gas supply. Around the tube 7 and tube 4 with a pipe 11 there is a device 12 for heating and maintaining the temperature, made in the form of a massive block of stainless steel, equipped with a heating element, a temperature sensor and a power supply unit (not shown in the diagram). The injection tube 13 is made in the form of a thin-walled tube (outer diameter 2 mm, wall thickness 0.15 mm) of stainless steel. Material "A", containing the sample, for example, an aerosol filter or "Tepah" sorbent between two glass wool swabs, is placed near the end 14 of the tube 13. The end 14 of the tube 13 is placed in the tube 7 with a gap relative to its inner walls. The end 2 of the inner tube 1 is passed through the tube 4 and installed inside the injection tube 13 in front of the material "A". The end 15 of the injection tube 13 is connected by means of a quick-release tight connection 16 and a flexible pipe 17 (not shown in the diagram) to the booster 18 of the carrier gas flow.

The device works as follows. Submission for analysis is preceded by a sampling procedure. Aerosols from the air are taken to the filter by passing a certain volume of air through it. Pairs of organic substances from the air are taken to the sorbent, which is equipped with the injector tube 13 by passing through it a certain amount of air. Organic substances from volatile solvents are taken onto the sorbent provided with the injection tube 13 by applying an aliquot of the solution and then removing the solvent from the sorbent by passing a sufficient volume of carrier gas through the injection tube 13.

To maintain the device in working order, a gas flow driver (not shown in the diagram) is connected through the detector 3 to the tube 1, which ensures a continuous gas flow from the device to the detector 3 through the open end 2 and the channel of the inner tube 1 with a flow rate Q1; the carrier gas is continuously supplied at a flow rate Q2>Q1 from the exciter 10 to the branch pipe 11, tubes 4, 7 and from tube 7 through end 8 into the environment, which prevents the environment from penetrating into tube 1 through end 8 and tube 7. device 12 for heating and maintaining the temperature.

At the first stage, the stage of preparation for submitting a sample for analysis, the end 15 of the injection tube 13 is connected by means of a connection 16 to the nozzle 17, the flow booster 18 is turned on with a flow rate Q3 and some time is expected to fill the nozzle 17 and tube 13 with gas; end 14 of tube 13 is placed in front of end 8 outside tube 7.

In the second stage, the stage of submitting the sample for analysis, the tube 13 is quickly inserted inside the outer tube 7, while the material "A" is in front of the end 2 of the tube 1. The end 14 of the tube 13, due to contact with the walls of the tube 7 and the carrier gas, as well as thermal radiation, heats up together with the material "A" and the sample. The tube 13 is kept in the tube 7 for the time necessary to heat the end 14 of the tube 13 with the material "A" and supply the sample with the carrier gas flow from the tube 13 through the end 2 into the tube 1. When Q1<Q3, the sample is fed into the tube 1 no loss.

The device is used in the product Mobile Chromato-Mass Spectrometer MHMS "Naval" (GO.3.09.00, ITs604S600TU), designed to detect, identify and decipher the structure of toxic chemicals in gaseous and liquid samples.

The most common use of the device is the analysis of impurities of gases and vapors of organic substances in the atmospheric air. In this embodiment, the injection tube contains a layer of powdered sorbent, which is fixed by gas-permeable plugs, and sampling is carried out by passing a certain volume of air through it. The above articles describe the use of the device in combination with chromato-mass spectrometric detection: for the analysis of organophosphorus toxic substances in the air (Makas A.L., Troshkov M.L. Field gas chromatograhy - mass spectrometry for fast analysis // Journal of chromatography B. - 2004. - T 800. - No. 1-2. - C. 55-61), methyl mercaptan and dimethyl sulfide (Kudryavtsev A.S., at al The method for on-site determination of trace concentrations of methyl mercaptan and dimethyl sulfide in air using a mobile mass spectrometer with atmospheric pressure chemical ionization, combined with a fast enrichment/separation system // Talanta, 2014, vol. 123, pp. 140-145); sulfur- and selenium-containing substances in the emanations of sulfide-containing dumps (Bortnikova S., et al, Mechanisms of low-temperature vapor-gas streams formation from sulfide mine waste Science of the Total Environment // - 2019. - Volume 647. - P.411- 419).

The disadvantage of the prototype is the need for additional sample preparation in the analysis of impurities or traces of non-volatile substances located on surfaces or inside solid materials. That is, to perform the analysis, the analytes must first be transferred either into the vapor phase by heating the sample, or into solution by extraction. Both require additional materials and time. In this case, a change in the qualitative and quantitative composition of the analyte may occur, which reduces the reliability of the analysis.

The claimed utility model solves the problem of analyzing traces of low-volatile substances located on surfaces or inside solid materials without an additional sample preparation step.

The technical result of the claimed utility model is to increase the speed, reliability, and also simplify the analysis of impurities, traces of hardly volatile substances located on surfaces or inside solid materials.

The claimed technical result is achieved in that a removable sample carrier is used to transfer a sample containing low-volatile substances into the injection tube, and a fixation device is used to accurately position it in the injection tube, preventing contact of the sample carrier with the inner tube. A sample containing non-volatile substances is transferred to the carrier as a result of contact with the surface of the object under study, mainly due to adhesion.

Before the sample is submitted for analysis, the removable sample carrier is placed in the injection tube and positioned in it using the fixation device in such a way that when the sample is submitted for analysis, the sample carrier does not come into contact with the open end of the inner tube. The sample carrier has a low heat capacity and is placed with a gap relative to the inner walls of the injection tube. As a sample carrier, a piece of tube or wire is used, as well as particles of the analyzed material itself.

To ensure a quick and easy change of the sample carrier, the device is placed in space in such a way that the sample carrier in the injector tube, when fed for analysis, is acted upon by gravity directed towards the open end of the inner tube. A metal mesh or other heat-resistant gas-permeable barrier with a small heat capacity installed in the injection tube is used as a device for fixing the sample carrier.

The device is illustrated by drawings, which show:

On FIG. 1 - Scheme of a known device.

On FIG. 2 - Scheme of the new device.

On FIG. 3 - The procedure for taking and introducing a sample of the sweat-fat layer from the surface of human skin.

On FIG. 4 - Photo of the surface of the sample carrier before and after sampling.

On FIG. 5 - Results of chromato-mass-spectrometric analysis of sweat-fat layer on the surface of human skin.

The device diagram is shown in Fig. 2. The device includes an inner tube 1, representing a quartz capillary column for gas chromatography, the end 2 of which is made open, and the other end is connected through the detector 3 to a gas flow driver (not shown in the diagram), which is a vacuum pump. The intermediate tube 4 has an open end 5, and a plug 6 is installed at its other end. The end 2 of the inner tube 1 is passed through the plug 6. The outer tube 7 has an open end 8, and its other end 9 is docked with the end 5 of the tube 4. Channel isolation unit The outer tube 7 from the external environment is made in the form of a carrier gas flow driver 10 connected by means of a pipe 11 to an intermediate pipe 4. The carrier gas flow driver 10 is a vessel with a carrier gas under pressure, equipped with a valve for regulating the gas supply. Around the tube 7 and tube 4 with a pipe 11 there is a device 12 for heating and maintaining the temperature, made in the form of a massive block of stainless steel, equipped with a heating element, a temperature sensor and a power supply unit (not shown in the diagram). The injection tube 13 is made in the form of a thin-walled tube (outer diameter 2 mm, wall thickness 0.15 mm) of stainless steel. For the purpose of quick and easy transfer of a sample containing hardly volatile substances, the “A” sample carrier has a low heat capacity, is made removable, for example, in the form of a piece of wire or a metal tube and is placed near the open end 2 of the inner tube with a gap relative to the inner walls of the injector tube 13. Particles of the analyzed material itself can also be used as a sample carrier.

Placing the removable "A" sample carrier with a gap relative to the inner walls of the injector tube ensures its quick and easy change. The device is placed in space in such a way that the sample carrier in the injector tube, when submitted for analysis, is acted upon by gravity directed towards the open end of the inner tube, and in order to fix its position and prevent contact with the inner tube 1, a fixation device 19 is introduced with a small heat capacity, made in the form of a mesh or other gas-permeable barrier made of a heat-resistant and inert material.

The device works as follows.

Submission for analysis is preceded by a sampling procedure. For sampling, the removable sample carrier is brought into contact with the surface, as a result of which hardly volatile substances from the surface under study are partially transferred to its surface, mainly due to adhesion.

To maintain the device in working order, a gas flow driver (not shown in the diagram) is connected through the detector 3 to the tube 1, which ensures a continuous gas flow from the device to the detector 3 through the open end 2 and the channel of the inner tube 1 with a flow rate Q1; the carrier gas is continuously supplied at a flow rate Q2>Q1 from the exciter 10 to the branch pipe 11, tubes 4, 7 and from tube 7 through end 8 into the environment, which prevents the environment from penetrating into tube 1 through end 8 and tube 7. device 12 for heating and maintaining the temperature.

At the first stage, the stage of preparation for submitting a sample for analysis, a removable carrier with a sample "A" is placed in the injection tube 15, its position, for example, due to gravity, is positioned by the fixation device 19. Next, the end 15 of the injector tube 13 is connected by means of a connection 16 to the nozzle 17, the flow booster 18 is turned on with a flow rate Q3 and some time is expected to fill the nozzle 17 and tube 13 with gas; end 14 of tube 13 is placed in front of end 8 outside tube 7.

In the second stage, the stage of submitting the sample for analysis, the tube 13 is quickly inserted inside the outer tube 7, while the removable carrier of the sample "A" is in front of the end 2 of the tube 1. The end 14 of the tube 13, due to contact with the walls of the tube 7 and the carrier gas, as well as thermal radiation, heats up together with the removable carrier of the “A” sample. As a result of heating, desorption of substances from its surface occurs. The tube 13 is held in the tube 7 for the time necessary to heat the end 14 of the tube 13 with the removable sample carrier "A" and to feed the sample with the carrier gas flow from the tube 13 through the end 2 into the tube 1. When Q1<Q3, the sample is fed into the tube 1 is lossless.

An example of the implementation of the utility model.

To confirm the technical result, an experimental test was made of the possibility of analyzing microimpurities of low-volatile substances accumulated in the sweat-fat layer on the surface of human skin using the proposed sampling and sampling device. The verification was carried out using the product Mobile chromato-mass spectrometer MHMS "Naval" (GO.3.09.00, ITs604S600TU) (LLC "SIBEL", Novosibirsk), which was equipped with the proposed device.

A piece of stainless steel wire with a diameter of 0.8 mm and a length of 1 cm was used as a removable sample carrier. The carrier was preliminarily cleaned of impurities and annealed at 300°C. The sampling and injection procedure is shown in Fig. 3. In FIG. 3A shows the sample carrier and injection tube. To transfer the sweat-fat layer sample from the skin surface, the carrier was placed between the donor's thumb and forefinger and rolled between them several times (Fig. 3B). After that, it was introduced into the injection tube (Fig. 3B) and, under the action of gravity, was positioned by the fixation device located in its lower part. Preparation for operation of the sample injection device and implementation of the sample injection (Fig. 3D) was performed in accordance with the above description. The result of sampling from the skin surface is shown in Fig. 4. A photograph of the surface of the sample carrier with a diameter of 0.8 mm before sampling, obtained using an electron microscope, is shown in FIG. 4A, after sampling, in FIG. 4B. The mass of the sample transferred to the sample carrier as a result of adhesion is estimated in the range of 1÷10 µg.

Chromato-mass-spectrometric analysis parameters:

Mass spectrometer parameters:

ion source: electron ionization;

scanning speed 2 spectra per second;

range of recorded masses: 45÷400 amu

Sample Injector Options:

desorption temperature: 300°C;

carrier gas flow into the chromatographic column Q1=2 ml/min.

insulating carrier gas flow through the outer tube Q2=10 ml/min.

carrier gas flow through injector tube Q3=2 ml/min.

Chromatography parameters:

carrier gas: helium

column parameters: length - 15 m, diameter - 0.32 mm, thickness of the stationary liquid phase (SSP) - 0.5 µm, SLP type: Rtx-200MS, Restek, USA

temperature programming mode: initial temperature 170°С; isotherm 3 min.; heating 12°C/min to 270°C; isotherm 2 minutes.

The obtained GC/MS data were processed using the AMDIS (Automatic Mass Spectral Deconvolution and Identification System) software. The identification of individual components was carried out using the NIST/EPA/NIH Mass Spectral Library (2017).

The results of the analysis are shown in Fig. 5. In FIG. 5A is a total ion current chromatogram. In FIG. 5B shows a mass fragmentogram for the 149 amu ion, which is characteristic of phthalic acid esters - phthalates. On FIG. 5B shows the mass spectrum of the substance with a release time of 8.1 minutes, identical to the mass spectrum of diethylhexyl phthalate. Using a mass spectral library, dibutyl phthalate, diisobutyl phthalate, diethylhexyl phthalate, diethylhexyl isophthalate, diisononyl phthalate were identified. Thus, the possibility of using the proposed device for the operational characterization of microimpurities that are in the form of traces on the surface, in this case, phthalates accumulated in the human lipid layer, is shown.

Claims (4)

1. A device for submitting samples for analysis, which includes an inner tube, one end of which is open, and the other end is connected through a detector to a means for inducing gas flow, an intermediate tube, one end of which is open, and the other has a plug through which the open end is passed the inner tube, the outer tube, one end of which is open, and the other end is docked with the open end of the intermediate tube, the heating and temperature maintenance device located around the outer and intermediate tubes, the injection tube with the sample carrier, one end of which is open, is located in the outer tube with a gap relative to its inner walls and is installed outside the open end of the inner tube, and the other end is placed outside the outer tube and connected by means of a quick-detachable hermetic connection and a flexible pipe to the carrier gas flow exciter; carrier gas flow exciter connected by means of a branch pipe to an intermediate tube, characterized in that in the injector tube between the sample carrier and the open end of the inner tube there is a device for fixing the position of the sample carrier, made in the form of a grid or other gas-permeable barrier made of a heat-resistant and inert material, and the sample carrier is placed with a gap relative to its inner walls. 2. The device according to claim 1, characterized in that the sample carrier is made in the form of a piece of wire or a metal tube. 3. The device according to claim 1, characterized in that particles of the analyzed material are used as the sample carrier. 4. The device according to claim 1, characterized in that several sample carriers are simultaneously placed in the injection tube.

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