JP2009002711A - Method and device for enriching sample - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a high-boiling point component from being adsorption-lost by a moisture removing operation essential when trapping a component in the atmosphere to be introduced into an analyzer, to enhance sensitivity for the high-boiling point component, to enhance a moisture removing rate, and to enhance analytical precision for the high-boiling point component. <P>SOLUTION: In this enriching method of the present invention, a sample squeezed by a canister or the like is trapped at first into the first trap, without operating a moisture removing device or passing it therethrough, to be separated into a sample fed to the analyzer as it is, and a sample passed through the moisture removing device to be trapped into the second enriching trap, and the sample discharged from the second enriching trap is moisture-removed by the moisture removing device, to be fed to the analyzer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a sample concentration method and apparatus for measuring a predetermined substance in a gas (atmosphere) sample.

It is already known that exposure to harmful volatile organic compounds (VOCs) in the atmosphere causes various health hazards to the human body. Therefore, it is an important issue to accurately measure the atmospheric concentration of the target volatile organic compound component.
Since the target component is present in a very small amount in the atmosphere, collection and adsorption by an adsorbent (hereinafter referred to as trap) and subsequent concentration are required and performed for measurement and analysis.

  As a conventional trapping technique for target components, there is a trap tube as shown in FIG. A gas sample is passed through a trap tube, and the sample is trapped by the filled TENAX / active carbon to adsorb moisture on silica. By appropriately controlling the temperature of the trap tube, the trapped sample is desorbed, and the moisture adsorbed on the silica is desorbed at different timings later than the sample other than the moisture. Therefore, the flow path is switched before moisture desorption, and sample components from which moisture has been removed are introduced into the analysis system.

However, the trap tube has a low heat-resistant temperature (for example, about 220 ° C.) and cannot desorb high-boiling components. Further, there is a problem that silica is melted when heated to a temperature higher than the heat resistant temperature. Here, the high boiling point component is a high boiling point region in volatile components (for example, C _{2 to} C ₁₆ ), and does not propose a specific temperature range. Examples of the high boiling point component include 1,2,4-trichlorobenzene (213 ° C.), hexachloro-1,3-butadiene (215 ° C.) and the like as typical substances.

In order to solve the above problem, there are systems as shown in FIG. 2 (at the time of sample introduction) and FIG. 3 (at the time of sample delivery) as traps provided with a water removal mechanism. The sample collected by the canister 1 is trapped (concentrated) from the passage 2 through the moisture removal mechanism 3 and into the trap tube 4 (T2) (the moisture removal mechanism 3 is not acting at this time). The moisture of the sample trapped (concentrated) in the trap tube 4 is removed using a moisture removing mechanism (MCS or the like) 3, and the sample other than the moisture is sent to the analyzer 5 through the passage 2.
At this time, as an example, the trap temperature of the trap tube 4 is −100 ° C. and the heat desorption temperature is 200 ° C. as indicated by T 2 in the upper stage of FIG. 17 (see Patent Document 1).

Japanese Patent No. 3601921

  In this way, each component in the sample is trapped in one concentration trap, then heated and desorbed, and the moisture is removed by the moisture removal mechanism 3 and sent to the analyzer 5. When the temperature of the removal mechanism 3 is raised, the water removal efficiency decreases. Further, when the temperature is lowered, the high boiling point component also remains in the moisture removing mechanism (MCS, etc.) 3 (adsorption loss at the moisture removing unit).

  When the chromatogram in the analysis of the target component prescribed in the volatile organic analysis method TO-14 of the US Environmental Protection Agency (EPA) is shown in FIG. 4, when the MCS is set to 20 ° C., the high boiling point component becomes the moisture removal mechanism. Adsorption loss occurs (Fig. 5). When the temperature of MCS3 is raised to 50 ° C, the sufficient water removal function does not work, and a large amount of water is introduced into the analyzer, resulting in poor analysis accuracy and unstable analysis. The water chromatogram is clear as shown in FIG.

  Therefore, in the present invention, a plurality of trap mechanisms are provided, a sample collected by a canister or the like is divided into a high-boiling component and other components, and the high-boiling component is removed from the participation of the water removal mechanism by a high-boiling component. We propose a method and apparatus that increases the sensitivity of components, improves the moisture removal rate, and improves the analysis accuracy of low-boiling components.

  The present invention as a means for solving the above problems is an apparatus provided with a plurality of concentration traps and a water removal mechanism. The sample trapped in at least one concentration trap is transferred to the analyzer without operating the water removal mechanism. The sample that is sent and trapped in another concentration trap is a sample concentration method that removes moisture by a moisture removal mechanism and sends the sample to an analyzer.

  In addition, in the above method, at the time of sample introduction, a part of the sample is trapped in the concentration trap without passing through the moisture removing device, and is sent to the analyzer as it is, while the remainder is trapped in another concentration trap, It is a sample concentration method characterized by removing moisture by a moisture removal mechanism and sending it to an analyzer.

  In the above method, in the apparatus in which a plurality of concentration traps communicate with both sides of the moisture removal mechanism, when the sample is introduced, the sample corresponding to each concentration trap is trapped, and the high boiling point component passes through the moisture removal mechanism. In this case, the sample concentration method is characterized in that the sample is sent to the analysis device without being performed.

  Further, in the above method, in an apparatus in which a plurality of concentration traps are communicated with both sides of the moisture removal mechanism, the high boiling point component is trapped in the first concentration trap, and the remainder is communicated therewith by disabling the moisture removal mechanism. 2. A sample which is trapped in the concentration trap, and is desorbed from the second concentration trap side, and the sample from which moisture has been removed by the moisture removal mechanism and the sample desorbed from the first concentration trap are sent to the analyzer. Concentration method.

  Further, the sample concentrating device is characterized in that a concentration trap is provided on both sides via a moisture removing mechanism, each device is configured to be temperature-controllable, and one of the concentration traps communicates with the analyzer.

  According to the first and second aspects of the present invention, a part of the sample, for example, a high boiling point component is trapped in a concentration trap and sent to the analyzer as it is when desorbed. And it can analyze stably.

  According to the invention described in claim 3, in addition to the effects of the inventions described in claims 1 and 2, it is not necessary to trap the high boiling point component in the first concentration trap and pass through the water removing device. There is no loss of ingredients.

  According to the invention described in claim 4, in addition to the effects of the invention described in claims 1-3, the remaining sample that passes through the moisture removing device should avoid a high temperature at which a large amount of moisture is introduced, for example, 50 ° C. Thus, the operation can be performed at a low temperature, for example, 20 ° C., the analysis accuracy can be prevented from being lowered, and the instability factor of the moisture removal mechanism can be removed.

According to the invention described in claim 5, in addition to the effects of the invention described in claims 1 to 4, the operation is simple and efficient, the analysis process can be simplified, and the mechanism is extremely simple. We can propose cost reduction and work efficiency, and can secure the reliability of analysis.
In addition, the amount of liquid nitrogen used can be reduced.

  The present invention will be described with reference to the flowchart shown in FIG. A large number of sample collection containers 11, 11,..., For example, stainless canisters, glass bottles, bags, etc., are installed on a stand or the like and connected to the trap system body 13 via switching valves 12, 12,. The sampling containers 11, 11,... Can be placed in a desired number of sampling states selectively or simultaneously.

  The trap system body 13 is provided with an MCS (moisture removal mechanism) 14 and is connected to the switching valve 12, the concentration trap 15, and the cryofocus 16. A concentration trap 15 as a first concentration trap is connected to a mass flow controller 17, and the mass flow controller 17 is connected to a vacuum pump 18 such as a diaphragm pump.

  Each mechanism is controlled by a microprocessor 20 controlled by control software 19. The GC column oven 21 is connected to the analysis device 22, and on the other hand, is connected to the trap system main body 13, an example of which is the cryofocus 16.

Further, a sample selector 23 is provided between the sample collection container 11 and the switching valves 12 and 12 so that the connection with the desired container 11 can be made freely.
A characteristic mechanism in the present invention is that the two concentration traps 15 (first concentration trap) and 150 (second concentration trap) are connected via the moisture removal mechanism 14. One of the concentration traps 15 and the sampling container 11 and the analyzer 22 can be connected and switched freely.

  As another mechanism, the concentration traps 15 and 150 are connected, and an intermittent mechanism, for example, a cock is provided between them, and each mechanism and further the water removal mechanism 14 is connected to the concentration trap 150, and the analyzer 22 is connected. A mechanism that connects them is also conceivable.

Connection between each apparatus is carried out by a necessary connecting pipe, and it is conventionally known to install a multi-way valve and a switching valve at a necessary portion.
Further, a series of operations for the operation and control of each device is incorporated in the control software 19, and the microprocessor 20 controls the temperature of the concentration trap, the control of the MCS, the control of the MCS, for example, the control of the collection container for sampling. It is a matter of course that known techniques control the control of the overall equipment and the overall flow, such as focus temperature control, control of various devices of the mass flow control roller, and switching control of each valve.

The method of the present invention will be described following the steps shown in FIG.
In the method of the present invention, in the first stage, the sample is introduced from the sampling container 11 into the concentration trap 15, the high boiling point component is trapped, and the remaining sample is passed through the MCS 14 that does not act on the moisture removal function. 150.

At that time, the high-boiling component is trapped in the concentration trap 15, and the sample other than the high-boiling component is trapped in the concentration trap 150.
Next, dry purge is performed using nitrogen gas.

  Subsequently, the concentration traps 15 and 150 are preheated to prepare for sample desorption. Next is desorption. The sample trapped in the concentration traps 15 and 150 is desorbed by heating and sent to the analyzer 22.

Next, each device is cleaned by heating in a bake.
For example, the concentration traps 15 and 150, the moisture removing device 14 and the like are heated and cleaned. If necessary, they are cleaned with a cleaning gas. By this series of operations, the sample collected in a sample container such as a canister is analyzed.

Next, the mechanism and each operation will be described.
First, sample introduction will be described with reference to FIG.
The concentration traps 15 and 150 are provided with conventionally known cooling and heating devices, and are configured to be controllable to a required temperature.
As a configuration thereof, a trap pipe and a cooling mechanism surrounding the trap pipe, flowing a refrigerant and cooling the trap pipe, and a heating mechanism for heating the trap pipe as necessary, for example, a resistance heating element can be wound. This temperature control selectively concentrates and holds the desired components in the concentration traps 15 and 150 from the sent sample gas.

  The sample collected by the canister 11 is introduced into the concentration trap 15. In the concentration trap 15, a heavy (high boiling point) sample is concentrated (concentrated). All other samples (samples containing moisture other than the high boiling point) are introduced into the trap 150 through the moisture removing mechanism 14. At this time, the moisture removing mechanism 14 is not operating. As the temperature of the concentration trap at the time of collection, as shown in FIGS. 18 to 22, the temperature corresponding to the sample is set according to the temperature example of the filler.

In the example of the trap of the conventional apparatus shown in FIGS. 2 and 3, -100 ° C. of T2 in FIG. 17 is used at the time of sample collection, and the heating (desorption) temperature shown in FIG. in use.
In the present invention, as an example in the TO-14 analysis example, TRAP uses T1 TRAP temperature of 35 ° C. and heating / desorption temperature of 200 ° C. shown in FIG.

In the prior art, the cooling that has been performed on the entire trap tube is made to cool only necessary portions by dividing the trap tube as in the present invention. As a result, it has become possible to reduce the amount of liquid nitrogen used for cooling so far.
Conventionally, trapping was performed using a single trap tube (for example, 20 cm), and the whole was cooled with liquid nitrogen. However, by dividing into multiple (two, etc.) as in this case, each trap tube is shortened. (Less than 10 cm, etc.) The trap tube cooled by liquid nitrogen can be used only at a necessary location or can be disabled depending on the target component.
By this temperature control, effects such as a reduction in the amount of liquid nitrogen used in the cryofocus 16 were found.

Subsequent to this sample introduction, sample desorption and sample feeding into the analyzer are performed. First, DRY Charge is performed. The dry purge is an operation of expelling light gas (such as CO ₂ in the atmosphere) with nitrogen gas through the concentration trap 15, the moisture removal mechanism 14, and the concentration trap 150.
In this state, moisture and other components not required for analysis such as CO ₂ are removed from the concentration traps 15 and 150. If necessary, it is removed from the concentration traps 15 and 150 by the heating unit via the control device. This leads to the next preheat.

  Next, PreHeat is performed. This is an operation for preheating the trap 15 or the traps 15 and 150. Set to the set temperature before desorption. As a result, the influence of the temperature rising time up to the set temperature can be eliminated.

The moisture removal mechanism (MCS) will be described. MCS is an abbreviation for moisture control system. In MCS, moisture is high in concentration and easily reaches the dew point temperature. Therefore, MCS accumulates in MCS according to the principle of “condensation”, but VOC _S is low in concentration and difficult to reach dew point temperature. Therefore, most of them pass through MCS. Using this principle, water is removed. At this time, the cooling fan may or may not be operated if the moisture removal mechanism is low enough to act.
In addition to MCS, a hygroscopic resin such as Nafion (registered trademark of DuPont) can also be used to remove moisture.

Next, desorption will be described.
At this time, the high-boiling sample is trapped (concentrated) in the concentration trap 15 and the non-high-boiling sample containing moisture in the concentration trap 150. The target component is desorbed by the carrier gas and introduced into the analytical instrument 22 (gas chromatograph or mass analyzer). The high-boiling component is removed from the concentration trap 15, while the sample in the concentration trap 150 is removed with a moisture removal mechanism 14 (MCS or the like. If there is another mechanism capable of removing moisture, it may be used). Are introduced into the analysis.
Conventionally, the high boiling point component has been lost due to adsorption or the like by the moisture removal mechanism 14, but in this system, the moisture removal mechanism 14 does not pass and is reliably trapped (concentrated) and introduced into the analyzer 22. The

  Bake is a process of removing components such as moisture of the moisture removal mechanism. Specifically, each part is heated and cleaned while flowing the carrier gas in the same direction as when the sample is delivered.

  18 to 22 are test methods (collection to analysis) for harmful chemical substances in the atmosphere in TO-14.

FIG. 14 is an analysis chromatogram of TO-14 based on an embodiment using the method and apparatus 13 of the present invention. In this method, the MCS temperature was lowered to 20 ° C., a sample was collected, and heat desorption was performed at 200 ° C.
When this result is observed with respect to the chromatogram FIG. 14, in the chromatogram FIG. 4 in which the high boiling point component is set to 20 ° C., only slight precipitation is recorded in the vicinity of the scale 349, whereas FIG. 15 shows the chromatogram. As shown in FIG.
Further, it is clear that the chromatogram of water is also reduced in comparison with FIG. 16 of the present invention as compared with FIGS. It was found to be substantially 1/5.

In Example 2, the sensitivity of each component extracted from the main component detected and recorded on the actual chromatogram in FIG. 14, FIGS. 24 and 25 on the chromatogram of the conventional method shown in FIGS. When the high-boiling component sensitivity comparison table is compared, the difference in the detected amounts of the high-boiling components 1,2,4-matetrichlorobenzene and hexachloro-1,3-butadiene is obvious.
In addition, according to the present invention, with a high boiling point component, a sensitivity twice as high as that of the conventional method can be obtained, and the introduction amount is reduced to 1/3 in the moisture removal rate.
Thus, according to the method of the present invention, the low adsorptivity of the high boiling point component and the running stability were supported.

  According to the chromatogram of the high boiling point component according to the method of the present invention in Example 2, it is understood from the chromatograms of FIGS. 5, 8, and 15 that the difference in the detected amount is obvious.

  The water introduction rate of the method of the present invention and the conventional method were compared by overwriting the chromatogram of the water of the present invention FIG. 16 and FIGS. 6 and 9 of the conventional method on one chromatogram diagram 26. It will be understood that the amount of water introduced in the method of the present invention is 1/5 that of the conventional method.

Conventional trap tube illustration Overview of conventional analyzer Overview of conventional analyzer One example chromatogram of the conventional analyzer shown in FIGS. Same as above Chromatogram of the above water Other Example Chromatogram of Conventional Analyzing Apparatus Shown in FIGS. Same as above Chromatogram of the above water System flow diagram of an example apparatus according to the present invention Example of apparatus according to the present invention Example work flow diagram An enlarged view of the main part of one embodiment of the present invention An enlarged view of the main part of one embodiment of the present invention 12 and 13 Example of chromatogram of the apparatus Same as above Chromatogram of the above water Example of trapping and desorption temperature with trap tube filler Example of collection and desorption temperature by the filler of the embodiment of the present invention Example of collection and desorption temperature by the filler of the embodiment of the present invention Example of collection and desorption temperature by the filler of the embodiment of the present invention Example of collection and desorption temperature by the filler of the embodiment of the present invention Example of collection and desorption temperature by the filler of the embodiment of the present invention Example of the present invention high boiling point component sensitivity table Sensitivity table for high boiling point components by the same MS example of the conventional analyzer Sensitivity table for high boiling point components by the same MS example of the conventional analyzer Comparison of water content between the chromatogram of the water shown in FIG. 16 of the present invention and the chromatogram of one embodiment of the conventional analyzer shown in FIGS.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Sampler 12 Switching valve 13 Trap system body 14 Moisture removal mechanism 15 Concentration trap 16 Cryofocus 17 Mass flow controller 18 Vacuum pump 19 Control software 20 Microprocessor 21 GC column 22 Analyzer 150 Concentration trap

Claims (5)

  In an apparatus equipped with multiple concentration traps and a moisture removal mechanism, the sample trapped in at least one concentration trap is sent to the analyzer without operating the moisture removal mechanism, and the sample trapped in the other concentration trap is moisture-removed. A sample concentration method characterized by removing water by a mechanism and sending it to an analyzer.   At the time of sample introduction, a part of the sample is trapped in the concentration trap without passing through the moisture removal mechanism and sent to the analyzer as it is, while the rest is trapped in another concentration trap, and moisture is removed by the moisture removal mechanism. The sample concentration method according to claim 1, wherein the sample is removed and sent to the analyzer.   In an apparatus in which a plurality of concentration traps communicate with both sides of the moisture removal mechanism, when the sample is introduced, the sample corresponding to each concentration trap is trapped, and the high boiling point component in the sample does not pass through the moisture removal mechanism. The sample concentration method according to claim 1, wherein the sample is concentrated.   In an apparatus in which a plurality of concentration traps communicate with both sides of the moisture removal mechanism, a high boiling point component in the sample is trapped in the first concentration trap, and the remainder is trapped in the second concentration trap through the inactive moisture removal mechanism, The sample concentration method according to claim 1, wherein the sample desorbed from the second concentration trap side and moisture removed by the moisture removal mechanism and the sample desorbed from the first concentration trap are sent to the analyzer. .   A sample concentrating apparatus, wherein concentrating traps are provided on both sides via a moisture removing mechanism, each concentrating trap is configured to be temperature-controllable, and one of the concentrating traps communicates with an analyzer.

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