JP2022135002A - Low-temperature concentration device and atmosphere concentration device - Google Patents

Abstract

To provide a low-temperature concentration device and an atmosphere concentration device capable of collecting a substance to be analyzed contained in sample gas to concentrate the substance, using a low-function and inexpensive cold storage refrigerator.SOLUTION: A low-temperature concentration device 1 comprises: a cold storage refrigerator 2; a heat conductor 3 having a first hole 31, and thermally connected to the cooling unit 21 of the cold storage refrigerator 2; a first sample conduit 6 having a first sample concentration unit 61 arranged in the first hole 31; an adsorbent 11 arranged in the first sample concentration unit 61; a first heating unit 8 that is arranged in the first hole 31, and heats the first sample concentration unit 61; and a heat insulating material 10 covering the heat conductor 3 and the first sample conduit 6. The first sample conduit 6 and the first heating unit 8 are separated from the inner wall of the first hole 31.SELECTED DRAWING: Figure 1

Description

The present invention relates to cryogenic concentrators and atmospheric concentrators.

Cryogenic concentrators are used, for example, to capture and concentrate volatile organic compounds (VOCs) contained in the atmosphere. The collected and concentrated volatile organic compounds are analyzed using, for example, a gas chromatograph-mass spectrometer. A volatile organic compound is a general term for organic compounds that have volatility and become gas in the atmosphere. Volatile organic compounds include a wide variety of substances such as toluene, xylene, ethyl acetate, and the like.

For example, in order to accurately analyze low-concentration volatile organic compounds contained in the atmosphere using a gas chromatograph mass spectrometer, etc., the volatile organic compounds, which are the substances to be analyzed, are collected in advance, concentrated, and used for analysis. There is a method to prepare a sample of

One such sample preparation method is the cryoconcentration method. This involves introducing a sample gas (eg, atmospheric air) containing an analyte (eg, volatile organic compounds) into a sample conduit cooled to a low temperature (eg, −190° C.) to liquefy the analyte within the sample conduit. After adsorbing on an adsorbent placed in the sample conduit, the sample conduit is rapidly heated to a high temperature (eg, 200° C.) to vaporize the analyte within the sample conduit or desorb it from the adsorbent. This is a method of removing contaminants contained in the sample gas and collecting and concentrating the substance to be analyzed. A refrigerant such as liquid nitrogen or a regenerative refrigerator such as a Stirling refrigerator can be used to cool the sample conduit. A resistance heater such as a nichrome wire heater can be used to heat the sample conduit.

As an apparatus for collecting and concentrating a substance to be analyzed by a low-temperature concentration method, Patent Document 1 discloses a Stirling refrigerator, a cooling unit cooled by the Stirling refrigerator, a heating unit heated by electric heat, and a heating unit. A cryogenic concentrator is described which includes a collection conduit embedded in a tube through which a sample gas is introduced, and which allows the cooling and heating sections to be brought into contact and separated. In addition, Non-Patent Document 1 has a Stirling refrigerator, an aluminum cold block cooled by the Stirling refrigerator, a heat insulating material covering the cold block, and a sample concentration part wound in a coil shape, A low-temperature concentration apparatus comprising a stainless steel tube into which a sample gas is introduced, an adsorbent filled in a sample concentration section, and a nichrome wire heater wound around the sample concentration section, wherein the sample concentration section is in contact with a cold block. is described.

WO2011/099079

Taku UMEZAWA, Stephen J. ANDREWS,and Takuya SAITO, “A Cryogen-Free Automated Measurement System of Stable CarbonIsotope Ratio of Atmospheric Methane”, Journal of the Meteorological Society of Japan, 93(1), pp. 115-127 (2020)

In cryogenic concentrators such as those described above, the temperature of the sample conduit is varied over a wide range (eg, from -190°C to 200°C or vice versa) in order to collect and concentrate the analyte contained in the sample gas. ), which must be changed rapidly, placing a heavy load on the regenerative refrigerator cooling the sample conduit. Therefore, a regenerative refrigerator with high refrigerating capacity is required, but such a regenerative refrigerator is generally expensive.

An object of the present invention is to provide a low-temperature concentrator and an atmospheric concentrator capable of collecting and concentrating a substance to be analyzed contained in a sample gas using a relatively low-performance and relatively inexpensive regenerative refrigerator. and

A low-temperature concentrator according to the present invention has a regenerative refrigerator, a heat conductor having a hole and thermally connected to a cooling part of the regenerative refrigerator, and a sample concentrator arranged in the hole. a sample conduit, an adsorbent disposed within the sample concentrating portion, a heating portion disposed within the pores to heat the sample concentrating portion, and an insulating material covering the heat conductor and the sample conduit; and the heating portion is spaced from the inner wall of the hole.

The low-temperature concentrator according to the present invention comprises a thermal conductor thermally connected to the cooling part of the regenerative refrigerator, and the sample concentrating part of the sample conduit is arranged in the hole of the thermal conductor. Since the sample concentration portion of the sample conduit is covered with the heat conductor, and since the heat conductor and the sample conduit are covered with the heat insulating material, the sample concentration portion is efficiently cooled by the regenerative refrigerator. be able to. Therefore, the substance to be analyzed contained in the sample gas can be easily and reliably adsorbed on the adsorbent arranged in the sample concentration section. In addition, since the sample enrichment part and the heating part for heating it are separated from the inner wall of the hole, even if the sample enrichment part is heated by the heating part in order to desorb the analyte substance from the adsorbent, the heat generated by the heating part is difficult to transfer to the heat conductor. Therefore, the load on the cold storage type refrigerator can be reduced. As described above, the low temperature necessary for collecting and concentrating the substance to be analyzed can be achieved by a relatively low-performance and relatively inexpensive regenerative refrigerator.

A cryogenic concentration device according to the invention may comprise a plurality of holes and sample conduits. In this case, a single device can perform multiple types of processing for the substance to be analyzed, such as primary concentration and secondary concentration. In addition, a single apparatus can be used to process a plurality of types of substances to be analyzed.

The cryogenic concentration apparatus according to the present invention may have an air layer between the sample conduit and the heating section and the inner wall of the hole. In this case, the air layer between the sample conduit and the heating section and the inner wall of the hole acts as a heat insulating layer to prevent heat conduction, so that the heat generated by the heating section is less likely to be transmitted to the heat conductor. Also, the structure of the cryogenic concentration apparatus can be simplified.

The low-temperature concentrator according to the present invention may further comprise an adiabatic tube arranged within the hole, and the sample concentrator and the heating section may be arranged in the adiabatic tube. In this case, the heat-insulating pipes present between the sample concentration section and the heating section and the inner wall of the hole impede heat conduction, so that the heat generated by the heating section is less likely to be transmitted to the heat conductor.

In the cryogenic concentration apparatus according to the present invention, the heat insulating tube may be made of glass. In this case, the heat-insulating pipe can be made from readily available materials.

The cryogenic concentration apparatus according to the present invention may further comprise a moisture-proof film arranged on the surface of the heat insulating material. In this case, since the heat insulating material is covered with the moisture-proof film, moisture does not enter the heat insulating material, and the heat insulating effect of the heat insulating material can be maintained for a long period of time.

The sample concentrator of the cryogenic concentrator according to the present invention may be a coiled portion of the sample conduit. In this case, the volume (length) of the sample enrichment part should be sufficiently secured so that the required amount of adsorbent for collecting and concentrating the substance to be analyzed can be placed inside the sample enrichment part, but the external dimensions of the sample enrichment part should be can be suppressed, and the sample concentration section can be accommodated compactly.

The regenerative refrigerator of the low-temperature concentrator according to the present invention may be a Stirling refrigerator. In this case, the low-temperature concentrator according to the present invention can be configured using a regenerative refrigerator that is easily available.

An atmospheric concentrator may be configured using the cryogenic concentrator of the present invention. In this case, the cryogenic concentrator of the present invention can be used to collect and concentrate analytes contained in the atmosphere.

According to the low-temperature concentrator and atmospheric concentrator according to the present invention, the low temperature necessary for capturing and concentrating the substance to be analyzed can be realized by a relatively low-performance and relatively inexpensive regenerative refrigerator. can.

It is a schematic diagram which shows the cross section of the cryogenic concentration apparatus which concerns on one Embodiment. It is a schematic diagram showing an example of an atmospheric concentrator provided with a cryogenic concentrator according to one embodiment. FIG. 4 is a diagram showing an example of temperature changes in the sample concentration section of the cryogenic concentration device according to one embodiment.

An embodiment of a cryogenic concentration apparatus according to the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the present invention is not limited to the embodiments described below. The technical scope of the present invention is defined based on the description of the claims. In the description of the drawings, the same elements are denoted by the same reference numerals, and overlapping descriptions are omitted.

FIG. 1 is a schematic diagram showing a cross section of a cryogenic concentration apparatus 1 according to one embodiment of the present invention.

As shown in FIG. 1, the cryogenic concentrator 1 includes a cold storage refrigerator 2, a heat conductor 3, a first heat insulating tube 4, a second heat insulating tube 5, and a first sample conduit 6. , a second sample conduit 7 , a first heating section 8 , a second heating section 9 and a thermal insulator 10 .

The cold storage type refrigerator 2 includes a cooling section 21, and the temperature of the cooling section 21 can be lowered to, for example, about -140.degree. Therefore, the cold storage type refrigerator 2 can take heat from an object in contact with the cooling unit 21 to cool the object. Specifically, the regenerative refrigerator 2 is a commercially available Stirling refrigerator. The regenerative refrigerator 2 is not limited to the Stirling refrigerator, and may be another type of regenerative refrigerator such as a Gifford-McMahon refrigerator.

The heat conductor 3 is a solid member made of aluminum having excellent heat conductivity, and is sometimes called a cold block. The heat conductor 3 is thermally connected to the regenerative refrigerator 2 . Specifically, it is in contact with the cooling part 21 of the cold storage type refrigerator 2 and is cooled by the cold storage type refrigerator 2 . The material of the heat conductor 3 is not limited to aluminum, but may be other substances with excellent heat conductivity, such as metals such as copper. The heat conductor 3 is provided with a first hole 31 and a second hole 32 . The number of holes is not limited to two, and may be one or three or more.

Each of the first heat insulating tube 4 and the second heat insulating tube 5 is a glass tube with one end open and the other end closed. As such a glass tube, for example, a commercially available glass test tube can be used. The first heat insulating pipe 4 and the second heat insulating pipe 5 are arranged inside the first hole 31 and the second hole 32, respectively, so that their closed ends are positioned at the innermost part of the hole. The material of the first heat insulating pipe 4 and the second heat insulating pipe 5 is not limited to glass, but as described later, it is possible to suppress an increase in the load on the cold storage refrigerator 2 and ensure a practical cooling rate. Materials with adequate thermal insulation properties are preferred. The first heat insulating pipe 4 and the second heat insulating pipe 5 are not limited to pipes with one end open and the other end closed, and may be pipes with both ends open.

The first sample conduit 6 and the second sample conduit 7 are both stainless steel tubes and placed inside the first and second heat insulating tubes 4 and 5, respectively. The material of the first sample conduit 6 and the second sample conduit 7 is not limited to stainless steel, and other substances may be used. The first sample conduit 6 and the second sample conduit 7 are preferably made of a material that does not react with the gas that flows through them.

A portion of the first sample conduit 6 inserted into the first heat insulating tube 4 near the closed end of the first heat insulating tube 4 is wound in a coil shape. This part is the first sample concentration part 61 . The first sample concentration portion 61 can be formed, for example, by winding a portion of the first sample conduit 6 over a length exceeding 100 mm into a coil having a diameter of approximately 10 mm.

Similarly, of the second sample conduit 7 inserted into the second heat insulating tube 5, the portion near the closed end of the second heat insulating tube 5 is wound in a coil. This part is the second sample concentration part 71 . The formation method and dimensions thereof can be the same as those of the first sample enrichment section 61 .

The adsorbent 11 is placed inside the first sample concentration unit 61 and the second sample concentration unit 71 by, for example, filling them.

When the first sample concentration portion 61 and the second sample concentration portion 71 are cooled, the temperature of the adsorbent 11 drops to a predetermined temperature (eg, −130° C.), and the first sample conduit 6 and the second sample conduit 6 and the second The analyte contained in the sample gas flowing through each of the sample conduits 7 is adsorbed together with contaminants also contained in the sample gas. Further, when the first sample concentration unit 61 and the second sample concentration unit 71 are heated, the temperature of the adsorbent 11 rises to a predetermined temperature (for example, −70° C.), and the adsorbed contaminants are removed. take off. After that, the temperature is raised by further heating, and when it reaches a predetermined temperature (for example, 100° C.), the adsorbed substance to be analyzed is desorbed. That is, the adsorbed substance to be analyzed is desorbed from the adsorbent 11 when the adsorbent 11 is heated to a predetermined temperature. A suitable adsorbent 11 can be selected according to the substance to be analyzed. For example, when the sample gas is air and the substance to be analyzed is trichlorofluoromethane, HayeSep D (trade name) manufactured by GL Sciences Inc. can be used as the adsorbent 11 .

The first heating unit 8 is arranged at a position where it can heat the first sample concentration unit 61, and can heat the first sample concentration unit 61 to, for example, about 100.degree. The first heating unit 8 is, for example, a Nichrome wire heater. In this case, the first heating section 8 may be wound around the first sample concentration section 61 . The nichrome wire heater as the first heating unit 8 is electrically connected to a power source (not shown) and heats the first sample concentrating unit 61 by generating heat when energized.

Similarly, the second heating section 9 is arranged at a position where it can heat the second sample concentration section 71 . Since the second heating section 9 is the same as the first heating section 8 except for this point, detailed description thereof will be omitted.

Since the first sample enrichment section 61 and the first heating section 8 are arranged inside the first heat insulating tube 4 and the first heat insulating tube 4 is arranged inside the first hole 31, the first Between the sample enrichment section 61 and the first heating section 8 and the inner wall of the first hole 31, the first heat insulating pipe 4 is present. Therefore, the first sample concentration section 61 and the first heating section 8 are separated from the inner wall of the first hole 31 and do not contact the inner wall of the first hole 31 .

Similarly, since the second heat insulating tube 5 is present between the second sample enrichment section 71 and the second heating section 9 and the inner wall of the second hole 32, the second sample enrichment section 71 and The second heating part 9 is separated from the inner wall of the second hole 32 and does not contact the inner wall of the second hole 32 .

The heat insulating material 10 covers the cooling part 21, the heat conductor 3, the first heat insulating tube 4, the second heat insulating tube 5, the first sample conduit 6, and the second sample conduit 7. there is The heat insulating material 10 is made of a material having excellent heat insulating properties, such as rigid urethane foam. The heat insulating material 10 prevents the heat from the external environment of the low-temperature concentrator 1 from entering the inside of the device, and suppresses an increase in the load on the regenerative refrigerator 2 .

The surface exposed to the outside of the heat insulating material 10 is covered with a moisture-proof film. The moisture-proof film prevents moisture in the external environment from entering the interior of the heat insulating material 10 . Thereby, the heat insulating effect of the heat insulating material can be maintained for a long period of time, for example, 1 to 2 years. A moisture-proof film can be formed, for example, by applying a paint generally called a surfacer.

In the cryogenic concentration apparatus 1 described above, the first sample concentration section 61 and the first heating section 8 are separated from the inner wall of the first hole 31, and the second sample concentration section 71 and the second heating section are separated from each other. Since 9 is separated from the inner wall of the second hole 32, there are effects as described below.

In the low-temperature concentrator 1 , the first sample concentration section 61 and the first heating section 8 are separated from the inner wall of the first hole 31 , so the first sample concentration section 61 is heated by the first heating section 8 . Even when heated, the heat generated by the first heating unit 8 and the heat possessed by the heated first sample concentration unit 61 are not directly transmitted to the heat conductor 3 . Therefore, an increase in the temperature of the heat conductor 3 is suppressed, and an increase in the load on the cold storage refrigerator 2 that cools the heat conductor 3 is suppressed. Compared to the case where the first sample concentrating part 61 and the first heating part 8 and the inner wall of the first hole 31 are in contact with each other, the load applied to the cold storage type refrigerator 2 is smaller, so that the analysis target substance can be achieved with a relatively low refrigeration capacity. Therefore, as the regenerator type refrigerator 2, a relatively inexpensive one with relatively low functionality can be used. In addition, since the temperature of the first sample concentration unit 61 can be adjusted to an appropriate value without considering the load on the cold storage type refrigerator 2, various chemical species contained in the sample gas can be analyzed. and various interfering components can be removed. In addition, since the second sample concentration section 71 and the second heating section 9 are separated from the inner wall of the second hole 32, the first sample concentration section 61 includes the second sample concentration section 71. And the heat of the second heating unit 9 is not directly transmitted. Therefore, the first sample concentration unit 61 can be heated or cooled without considering whether the second sample concentration unit 71 is heated or cooled. can be controlled independently of the temperature of the second sample concentrator 71 . Therefore, for example, the first sample concentration unit 61 can be heated to desorb the target substance, and at the same time, the second sample concentration unit 71 can be cooled to perform secondary concentration of the target substance. Furthermore, since the load on the cold storage refrigerator 2 is low and there is no moving part for switching between heating and cooling, the low-temperature concentrator 1 with excellent long-term stability can be provided.

Note that since heat is not directly transmitted from the first sample concentration portion 61 to the heat conductor 3, compared to the case where the first sample concentration portion 61 and the inner wall of the first hole 31 are in contact with each other, the The cooling speed of the sample concentration unit 61 of 1 cannot avoid a decrease. However, by making the heat conductor 3 from a material with excellent thermal conductivity (for example, a metal such as aluminum or copper) and increasing the volume of the heat conductor 3 to sufficiently increase the heat capacity, the cooling rate is practically acceptable. can be realized.

In addition, the heat conduction from the first sample enrichment section 61 and the first heating section 8 to the heat conductor 3 is affected by the heat insulation (thermal conductivity) of the material of the first heat insulation tube 4 and the thickness of the tube wall. receive. Therefore, by using a material having appropriate heat insulating properties as the material for the first heat insulating pipe 4 and by making the wall thickness of the first heat insulating pipe 4 appropriate, the cold storage type refrigerator 2 It is possible to set the cooling rate of the first sample enrichment section 61 to a practically acceptable level while suppressing such an increase in load.

That is, in the cryogenic concentration apparatus 1, the first heat insulating tube 4 is made of glass, but the material and the thickness of the tube wall of the first heat insulating tube 4 can be changed as appropriate. Furthermore, the first heat insulating pipe 4 can be omitted if a suitable heat insulating property is obtained by air. In this case, by separating the first sample concentration section 61 and the first heating section 8 from the inner wall of the first hole 31 by a predetermined distance, the first sample concentration section 61 and the first heating section 8 are separated from each other. Since an air layer having a predetermined thickness is formed between the first hole 31 and the inner wall, the heat of the first sample concentration section 61 and the first heating section 8 is not directly transmitted to the heat conductor 3. .

The effects of the separation of the first sample concentration section 61 and the first heating section 8 from the inner wall of the first hole 31 have been described above. Since the second sample concentrating section 71 and the second heating section 9 are separated from the inner wall of the second hole 32, the effect is the same as this, so the explanation is omitted.

FIG. 2 is a diagram schematically showing an example of an atmospheric concentrator 50 configured by incorporating the cryogenic concentrator 1 according to one embodiment of the present invention.

As shown in FIG. 2, the atmospheric concentrator 50 includes a cryogenic concentrator 1, a flow path selection valve 51, an 8-port switching valve 52, a 4-port switching valve 53, a 6-port switching valve 54, a dehumidifier 55, and a mass flow controller 56. , which are interconnected by conduits through which the gas flows. Also, the air concentrator 50 is connected to a helium gas supply source He, an air intake section A, a standard gas supply source SG, a pump P, an exhaust section V, and a gas chromatograph/mass spectrometer GC/MS.

The helium gas supply source He is supplied to the atmosphere at each of the passage selection valve 51, one of the plurality of ports (conduit connection portions) of the 8-port switching valve 52, and one of the plurality of ports of the 6-port switching valve 54. It is connected with the concentrator 50 . That is, there are a total of three connections between the air concentrator 50 and the helium gas supply source He, and helium gas is supplied from the helium gas supply source He to the air concentrator 50 through these three connections. The supply of helium gas from the helium gas supply source He connected to the channel selection valve 51 to the air concentrator 50 is performed only when the channel of the channel selection valve 51 is switched to the helium gas supply source He. will be

It should be noted that other inert gases can be used instead of helium gas, and other analyzers can be used instead of the gas chromatograph/mass spectrometer GC/MS. The standard gas is a gas having a known composition, and is used for calibration of an analyzer (a gas chromatograph mass spectrometer GC/MS in the illustrated example) connected to the atmospheric concentrator 50.

The flow path selection valve 51 is a valve that turns on or off connections between the air concentrator 50, the helium gas supply source He, the air intake section A, and the standard gas supply source SG. By operating the flow path selection valve 51, helium gas supplied from the helium gas supply source He, air taken in from the atmospheric air intake part A, and standard gas supplied from the standard gas supply source SG are selectively selected or It can be introduced into the atmospheric concentrator 50 at the same time.

The 8-port switching valve 52 is a switching valve having 8 ports, and each port can be switched and connected to either of the two adjacent ports depending on whether it is in the ON position or the OFF position. can. The 4-port switching valve 53 and the 6-port switching valve 54 are switching valves similar to the 8-port switching valve 52 except that they have four and six ports, respectively. In FIG. 2, connections between ports in the ON position are indicated by solid lines, and connections between ports in the OFF position are indicated by dashed lines.

Dehumidifier 55 removes moisture from the gas introduced into the conduit of atmospheric concentrator 50 . Moisture contained in the gas must be removed because it freezes when the gas is cooled by the cryogenic concentrator 1 and clogs the conduit. As the dehumidifier 55, for example, a gas dryer manufactured by Permapure can be used.

Mass flow controller 56 controls the mass flow rate of gas through the conduit. The mass flow controller 56 is connected with the pump P.

An example of a procedure for collecting and concentrating a volatile organic compound as a substance to be analyzed contained in the air using the air concentrator 50 will be described below. Substances to be analyzed include, for example, hydrocarbons and halogen-containing hydrocarbons, and specific examples include trichlorofluoromethane, methyl chloride, chloroform, benzene, toluene, ethane, and sulfur hexafluoride.

As a first step, the primary concentration of the substance to be analyzed is performed.

First, the 8-port switching valve 52 and the 4-port switching valve 53 are set to the ON position. As a result, the flow path selection valve 51 passes through the dehumidifier 55, the 8-port switching valve 52, and the 4-port switching valve 53 to reach one end of the first sample conduit 6 of the cryogenic concentration apparatus 1, and the other end of the first sample conduit 6. A flow path is formed from the end to the mass flow controller 56 through the 4-port switching valve 53 and the 8-port switching valve 52, and further to the pump P.

At the same time, the passage selection valve 51 is operated to turn on the connection between the air concentrator 50 and the air intake section A, and the air as the sample gas is introduced into the air concentrator 50 through the air intake section A at a predetermined flow rate. The sample gas flow rate is controlled by a mass flow controller 56 . The introduced sample gas passes through the dehumidifier 55, and after the moisture is removed by the dehumidifier 55, it passes through the 8-port switching valve 52 and the 4-port switching valve 53 to be the first sample in the low-temperature concentrator 1. It enters the conduit 6 at one end thereof. At this time, the first sample concentration unit 61 is cooled to a predetermined adsorption temperature, eg, -130°C. Various volatile organic compounds contained in the sample gas that has flowed into the first sample concentration unit 61 are adsorbed by the adsorbent 11 arranged in the first sample concentration unit 61, and primary concentration is performed. The remaining gas that has not been adsorbed flows out from the other end of the first sample conduit 6, passes through the 4-port switching valve 53, the 8-port switching valve 52 and the mass flow controller 56, and is It is discharged outside.

As a second step, the interfering components are removed.

The sample gas usually contains not only volatile organic compounds, which are substances to be analyzed, but also other components such as nitrogen, oxygen, carbon dioxide, and xenon. Therefore, the adsorbent 11 generally adsorbs some of the components other than the substance to be analyzed, and these components interfere with the analysis. Therefore, in the atmospheric concentrator 50, the interfering components in the analysis are removed as follows.

That is, the flow path of the flow path selection valve 51 is switched from the atmosphere intake portion A to the helium gas supply source He while the 8-port switching valve 52 and the 4-port switching valve 53 are maintained at the ON position. Then, instead of the sample gas, the helium gas supplied from the helium gas supply source He is sucked by the pump P and flows through the flow path. At this time, the substance to be analyzed is adsorbed on the adsorbent 11 by heating the first heating unit 8 by energization and raising the first sample concentrating unit 61 to an appropriate interfering component desorption temperature, for example, −70° C. The interfering component is desorbed from the adsorbent 11 while keeping it. The interfering components desorbed from the adsorbent 11 flow out of the first sample concentrator 61 together with the helium gas flowing through the channel, and are discharged to the outside of the air concentrator 50 by the pump P. A specific value of the interfering component desorption temperature is selected according to the adsorbent 11, the substance to be analyzed, and the interfering component.

As a third step, secondary concentration of the substance to be analyzed is performed.

First, while maintaining the 4-port switching valve 53 at the ON position, the 8-port switching valve 52 is switched to the OFF position, and the 6-port switching valve 54 is set to the OFF position. As a result, from the helium gas supply source He to the other end of the first sample conduit 6 of the cryogenic concentrator 1 via the 8-port switching valve 52 and the 4-port switching valve 53, and from one end of the first sample conduit 6 to 4 Through the port switching valve 53, the 8-port switching valve 52 and the 6-port switching valve 54, it reaches one end of the second sample conduit 7 of the cryogenic concentrator 1, and from the other end of the second sample conduit 7 the 6-port switching valve 54 and the A flow path is formed that reaches the exhaust portion V via the 8-port switching valve 52 .

At the same time, helium gas is supplied from the helium gas supply source He through one of the ports of the 8-port switching valve 52, and the helium gas passes through the 8-port switching valve 52 and the 4-port switching valve 53 to the cryogenic concentrator 1. It enters the first sample conduit 6 at the other end. At this time, the substance to be analyzed is desorbed from the adsorbent 11 by heating the first heating section 8 by energization and raising the desorption temperature of the first sample concentration section 61 to an appropriate desorption temperature, for example, 100.degree. The substance to be analyzed desorbed from the adsorbent 11 flows out from one end of the first sample conduit 6 together with the helium gas flowing through the channel, and passes through the 4-port switching valve 53, the 8-port switching valve 52 and the 6-port switching valve 54. from one end into the second sample conduit 7 of the cryoconcentrator 1 . At this time, the second sample concentration unit 71 is cooled to a predetermined adsorption temperature, eg, -120°C. The substance to be analyzed that has flowed into the second sample concentration unit 71 together with the helium gas is adsorbed by the adsorbent 11 arranged in the second sample concentration unit 71, and secondary concentration is performed. The remaining gaseous components (for example, carbon dioxide) that have not been adsorbed flow out from the other end of the second sample conduit 7 together with the helium gas flowing through the channel, pass through the 6-port switching valve 54 and the 8-port switching valve 52, and It is discharged to the exhaust section V.

As a fourth step, the cryogenically concentrated analyte substance is taken out from the atmospheric concentrator 50 .

First, the 6-port switching valve 54 is set to the ON position. As a result, the helium gas supply source He passes through the 6-port switching valve 54 to reach the other end of the second sample conduit 7 of the cryogenic concentrator 1, and from one end of the second sample conduit 7 passes through the 6-port switching valve 54 to the gas chromator. A channel leading to a tograph mass spectrometer GC/MS is formed.

At the same time, helium gas is supplied from the helium gas source He through one of the ports of the 6-port switching valve 54, and the helium gas passes through the 6-port switching valve 54 to the second sample conduit 7 of the cryogenic concentrator 1. flow into from the other end. At this time, the substance to be analyzed is desorbed from the adsorbent 11 by heating the second heating section 9 by energization and raising the desorption temperature of the second sample concentrating section 71 to an appropriate desorption temperature, for example, 100.degree. The substance to be analyzed desorbed from the adsorbent 11 flows out from one end of the second sample conduit 7 together with the helium gas flowing through the flow path, passes through the 6-port switching valve 54, and is extracted from the air concentrator 50. The extracted analyte substance is supplied to a gas chromatograph mass spectrometer GC/MS for subsequent analysis.

According to the above procedure, volatile organic compounds as substances to be analyzed contained in the air can be collected and concentrated.

FIG. 3 is a diagram showing an example of changes in the temperature T1 of the first sample concentration section 61 and the temperature T2 of the second sample concentration section 71 of the cryogenic concentration apparatus 1. As shown in FIG.

As shown in FIG. 3, the low-temperature concentrator 1 uses a commercially available Stirling refrigerator to reduce the temperature of the first sample concentrator 61 and the second sample concentrator 71 to -140.degree. can be lowered to some extent. In addition, the low-temperature concentrator 1 can control the temperatures of the first sample concentrator 61 and the second sample concentrator 71 independently and quickly within the range of -140°C to 100°C.

DESCRIPTION OF SYMBOLS 1... Low-temperature concentrator, 2... Regenerative refrigerator, 21... Cooling part, 3... Heat conductor, 31... First hole, 32... Second hole, 4... First heat insulating pipe, 5... Second Insulated tube 6 First sample conduit 61 First sample concentration unit 7 Second sample conduit 71 Second sample concentration unit 8 First heating unit 9 Second , 10: Heat insulating material, 11: Adsorbent, 50: Atmospheric concentrator.

Claims (9)

a cold storage refrigerator;
a heat conductor having a hole and thermally connected to the cooling part of the regenerative refrigerator;
a sample conduit having a sample concentration portion disposed within the bore;
an adsorbent disposed within the sample concentration unit;
a heating unit disposed in the hole for heating the sample concentration unit;
a thermal insulator covering the thermal conductor and the sample conduit;
the sample conduit and the heating portion are spaced apart from the inner wall of the hole;
Cryogenic Concentrator. comprising a plurality of said holes and said sample conduits;
The cryogenic concentration apparatus according to claim 1. An air layer is provided between the sample conduit and the heating unit and the inner wall of the hole.
3. The cryogenic concentration apparatus according to claim 1 or 2. further comprising a heat insulating tube disposed within the hole;
The sample concentration unit and the heating unit are arranged in the heat insulating tube,
The cryogenic concentration apparatus according to any one of claims 1-3. The heat insulating tube is made of glass,
5. The cryogenic concentration apparatus according to claim 4. Further comprising a moisture-proof film disposed on the surface of the heat insulating material,
The cryogenic concentration apparatus according to any one of claims 1-5. The sample enrichment part is a part in which a part of the sample conduit is wound in a coil shape.
The cryogenic concentration apparatus according to any one of claims 1-6. The cold storage type refrigerator is a Stirling refrigerator,
A cryogenic concentration apparatus according to any one of claims 1-7. An atmospheric concentrator comprising a cryogenic concentrator according to any one of claims 1-8.

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