JP2012154680A - Gas specimen introducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out specimen introduction by a precut method without providing a precolumn or a channel switching system exclusive for precut operation, in a gas specimen introducing device equipped with a measuring tube and a collection tube for concentrating a specimen.SOLUTION: A gas specimen analyzing device including a measuring tube 40, a specimen gas supply channel F1, a carrier gas supply channel F2, an exhaust channel F3, and a collection tube 51, is provided with: a first channel switching valve 20 for switching a load state in which the measuring tube 40 is interposed between the channel F1 and the channel F3, and an injection state in which the measuring tube 40 is interposed between the channel F2 and a gas analyzing device 2; and a second channel switching valve 30 for switching a collection tube interposing state in which the collection tube 51 is interposed between the channel F1 and the measuring tube 40 or between the measuring tube 40 nd the gas analyzing device 2, and a collection tube short circuit state in which the collection tube 51 is not interposed, in the load state or the injection state.

Description

  The present invention relates to a gas sample introduction device for introducing a sample gas into a gas analyzer such as a gas chromatograph device.

  In gas chromatographic analysis for a gas sample, a gas sample introduction device for introducing a sample gas into a flow of a carrier gas supplied to an analysis column is widely used. For sample introduction by such a gas sample introduction device, a sample gas is measured by a measuring tube provided in the flow path and a predetermined amount of sample gas is measured and introduced into the analytical column, and a concentration gas provided in the flow path is used. There is a method of concentrating and introducing it into an analytical column, and an apparatus that can be switched between both methods is widely used.

  FIG. 4 shows a function for switching between sample introduction using a measuring tube as described above (hereinafter referred to as a measurement mode) and sample introduction using a concentrating device (hereinafter referred to as a concentration mode). The flow-path structure of the conventional gas sample introduction apparatus provided with this is shown. The eight-way valve 110 can be switched between two states of a connection state indicated by a solid line and a connection state indicated by a dotted line in FIG. 4 by manual force or mechanical force. SVa to SVe are solenoid valves, and Ta to Tc are branch pipes. In addition, NO of each solenoid valve means a normally open port, NC means a normally closed port, and C means a common port. The gas inlet 162 and the mass flow controller 150 are for supplying the gas for pressurization in the sample container 200 or the dry purge of the concentrator 130 at a predetermined flow rate, but the details are omitted here.

  First, the operation in the weighing mode in the apparatus of FIG. 4 will be described. When the eight-way valve 110 is in the connection state indicated by the dotted line and the solenoid valves SVd and SVe are set to the NO side (that is, the C side and the NO side are connected), the sample gas collected from the sample container 200 by the needle 140 is After passing through the metering pipe 120 via the ports d and e, the gas is discharged from the gas outlet 172 via the ports h and a, the electromagnetic valve SVd, and the branch pipe Ta. At this time, the carrier gas supplied from a gas cylinder (not shown) or the like to the gas inlet 161 is sent to the analysis column via the electromagnetic valve SVe, the ports f and g, the branch pipe Tc, and the gas outlet 171.

  In this way, with the sample gas flowing through the measuring tube 120, the eight-way valve 110 is switched to the connection state indicated by the solid line in FIG. As a result, the carrier gas now passes through the measuring tube 120 via the ports f and e, and a certain amount of sample gas determined by the internal volume of the measuring tube 120 held in the measuring tube 120 is transferred to the carrier. The gas is pushed out and sent to the analysis column via the ports h and g and the branch pipe Tc. Note that the sample gas sent to the analysis column is separated for each component in the process of passing through the column, and is extracted from the column and sequentially detected by a detector.

  Subsequently, the operation in the concentration mode will be described. When the eight-way valve 110 is brought into a connected state indicated by a solid line, the solenoid valve SVe is set to the NO side, and the solenoid valve SVc is set to the NC side, the sample gas collected by the needle 140 is concentrated through the ports d and c. After passing through the collection pipe 131 provided in 130, the gas is discharged from the gas outlet 172 through the electromagnetic valve SVc and the branch pipe Ta. At this time, the collection tube 131 is cooled by a cooling means (not shown), and a predetermined component (sample component) in the sample gas is adsorbed in the collection tube 131 in the process of passing the sample gas through the collection tube 131. Is done. At this time, the carrier gas supplied from the gas inlet 161 flows into the analysis column via the electromagnetic valve SVe, the ports f and e, the measuring pipe 120, the ports h and g, the branch pipe Tc, and the gas outlet 171.

  After the sample component is adsorbed inside the collection tube 131 in this way, the eight-way valve 110 is switched to the connection state indicated by the dotted line, and the solenoid valve SVc is switched to the NO side and the solenoid valve SVe is switched to the NC side. Then, the carrier gas passes through the collection tube 131 in the direction opposite to the previous sample gas via the electromagnetic valve SVe, the branch pipe Tb, and the electromagnetic valve SVc. In this state, when the collecting tube 131 is rapidly heated by a heating means (not shown), the sample components adsorbed in the collecting tube 131 are desorbed at a stretch, so that the high-concentration sample components ride on the carrier gas flow. It flows out from the collection tube 131 and is introduced into the analysis column through the ports c and b and the branch tube Tc. As described above, according to the concentration mode, even if the sample component contained in the original sample gas is very small, it can be concentrated to increase the concentration and then sent to the analysis column, thereby improving detection sensitivity. The effect is obtained.

  As described above, in the gas sample introduction device having the function of switching between the conventional measurement mode and the concentration mode, the measurement tube 120 and the collection tube 131 are connected in parallel, and the sample gas sent from either one of these is supplied. It flows into the analytical column. Further, the entire amount of gas collected in the measuring tube 120 is introduced into the analysis column.

Japanese Patent Application Laid-Open No.7-103956

  By the way, in gas chromatographic analysis, a method called a pre-cut method in which a specific component is separated and removed from a sample gas and then introduced into an analysis column is known (see, for example, Patent Document 1). In the precut method, after sample gas is collected in a measuring tube, the sample gas in the measuring tube is introduced into the precolumn through the precolumn interposed between the measuring tube and the analytical column. Then, after introducing the target component (generally a low boiling point component) that elutes first from the precolumn into the analytical column, the precolumn is analyzed before the unnecessary component (generally the high boiling point component) remaining in the precolumn is introduced into the analytical column. Disconnect from the column. As a result, unnecessary high-boiling components can be prevented from being introduced into the analytical column, the analytical time can be shortened, and the analytical column temperature can be shortened, thereby extending the analytical column life. There is an advantage that you can.

  However, in order to execute such a precut method in the gas sample introduction device having the function of switching between the conventional measurement mode and the concentration mode, in addition to the measurement tube and the collection tube, Since it is necessary to provide a flow path switching system dedicated to the pre-cut operation, there is a problem that the apparatus configuration becomes complicated, leading to an increase in size and cost of the apparatus.

  The present invention has been made in view of the above points, and the object of the present invention is to perform switching between the weighing mode and the concentration mode, and further, dedicated to the precolumn and precut operation. An object of the present invention is to provide a gas sample introduction device capable of introducing a sample by a pre-cut method without providing a flow path switching system.

A gas sample introduction device according to the present invention made to solve the above problems is a gas sample introduction device for introducing a sample gas into a gas analyzer,
a) a measuring tube having a predetermined volume;
b) a sample gas supply channel for introducing the sample gas into the measuring tube;
c) a carrier gas supply channel for introducing a carrier gas into the measuring tube;
d) an exhaust passage for discharging the gas that has passed through the measuring pipe to the outside;
e) a concentrating means comprising a collecting tube containing the adsorbent and concentrating the sample gas by a thermal desorption method;
f) A load state in which the metering tube is inserted between the sample gas supply channel and the exhaust channel, and the metering tube is inserted between the carrier gas supply channel and the gas analyzer. A first flow path switching valve for switching between the injected state,
g) In the load state or the injection state, a collection tube insertion state in which the collection tube is interposed between the sample gas supply channel and the measurement tube or between the measurement tube and the gas analyzer; A second flow path switching valve that switches between a collecting pipe short-circuit state that does not interpose the collecting pipe;
It is characterized by having.

  According to the above configuration, the state in which the measuring tube and the collecting tube are connected in series and the state in which they are connected in parallel can be switched, and the sample collected in the measuring tube is further introduced into a gas analyzer such as a gas chromatograph device. In this case, a collecting tube can be connected to the downstream side of the measuring tube. Therefore, the sample gas collected in the measuring tube can be roughly separated by the interaction with the adsorbent in the collection tube and then introduced into the gas analyzer. At this time, when the analysis target component elutes from the collection tube and is introduced into the gas analyzer, the collection tube is separated from the carrier gas flow path, so that the analysis target component is eluted later than the analysis target component. Unnecessary components to be removed can be eliminated (that is, precut) without being introduced into the gas analyzer. That is, the present invention is a sample introduction device provided with a measuring tube and a collection tube for sample concentration, and makes the collection tube also function as the above-mentioned pre-column. Sample introduction by the precut method (hereinafter referred to as precut mode) can be performed without providing a path switching system.

  When the pre-cut mode is executed in the gas sample introduction device according to the present invention having the above-described configuration, the first flow path switching valve is set to the load state after the second flow path switching valve is set to the collecting pipe short-circuited state. . As a result, a flow path from the sample gas supply flow path to the exhaust flow path via the measuring tube is formed, and the measuring tube is filled with the sample gas (that is, the sample gas is collected in the measuring tube). Thereafter, the first flow path switching valve is set to an injection state, and the second flow path switching valve is set to a collection tube insertion state. As a result, a flow path from the carrier gas supply flow path to the gas analyzer through the measuring pipe and the collecting pipe is formed, and the sample gas in the measuring pipe is introduced into the collecting pipe together with the carrier gas to separate the components. The Then, after the component to be analyzed in the sample gas is eluted from the collection tube and introduced into the gas analyzer, a part of the separated component (analysis unnecessary component) remains in the collection tube. The second flow path switching valve is switched to the collecting pipe short-circuit state. Thereby, the collection tube is separated from the flow path of the carrier gas, and unnecessary components are precut.

  In addition, when performing measurement mode, after making the 2nd flow-path switching valve into the said collection pipe short circuit state, a 1st flow-path switching valve is first made into a load state. As a result, a flow path is formed from the sample gas supply flow path to the exhaust flow path via the measurement pipe, and the sample gas passes through the measurement pipe. After that, if the first flow path switching valve is brought into the injection state, a flow path from the carrier gas supply flow path to the gas analyzer is formed through the measuring pipe, so that the sample gas that has filled the measuring pipe is discharged. It is introduced into the gas analyzer along with the carrier gas flow.

  Further, when the concentration mode is executed, the second flow path switching valve is set in the collection pipe insertion state, and then the first flow path switching valve is first set in the load state. As a result, a flow path is formed from the sample gas supply flow path through the collection pipe and further through the measuring pipe to the exhaust flow path. At this time, the collection tube is cooled by a predetermined cooling means, whereby a predetermined component in the sample gas passing through the collection tube is adsorbed in the collection tube. In addition, it is good also as what adsorb | sucks a predetermined component at normal temperature without providing a cooling means. Thereafter, when the first flow path switching valve is in an injection state, a flow path is formed from the carrier gas supply means to the gas analyzer through the measuring pipe and the collection pipe. At this time, by rapidly raising the temperature of the collection tube by a predetermined heating means, the sample component adsorbed in the collection tube is desorbed, and the sample component rides on the flow of the carrier gas to the gas analyzer. be introduced.

  The flow path switching operation by the first flow path switching valve and / or the second flow path switching valve may be manually performed by the user, or may be performed by using a driving means such as a motor. It may operate according to a program or according to a user instruction.

The gas sample introduction device according to the present invention is as follows.
h) a purge gas supply channel for introducing a purge gas into the collection tube;
i) a purge gas discharge passage for discharging the purge gas that has passed through the collection pipe to the outside;
It is desirable that the second flow path switching valve be interposed between the purge gas supply flow path and the purge gas discharge flow path in the short circuit state of the collection pipe.

  According to such a configuration, after the sample is introduced, in a state where the collection tube is short-circuited from the carrier gas flow path (that is, the flow path from the carrier gas supply flow path to the gas analyzer), The remaining sample component can be discharged to the outside by the purge gas.

  As described above, according to the gas sample introduction device according to the present invention, in the sample introduction device provided with the measuring tube and the collection tube for sample concentration, the collection tube also functions as the above-described precolumn. be able to. For this reason, it is possible to introduce the sample by the precut method without providing a precolumn or a flow path switching system dedicated to the precut operation.

The schematic block diagram of the gas chromatograph using the gas sample introduction apparatus by one Example of this invention. The schematic block diagram of the gas chromatograph using the gas sample introducing device by another Example of this invention. The schematic block diagram of the gas chromatograph using the gas sample introduction apparatus by another Example of this invention. The schematic block diagram which shows an example of the conventional gas sample introduction apparatus.

  Hereinafter, an embodiment of a gas sample introduction device according to the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a gas chromatograph using the gas sample introduction device of this embodiment.

  As shown in FIG. 1, the gas chromatograph according to the present embodiment is roughly composed of a sample introduction unit 1, an analysis unit 2, and a control unit 3. The sample introduction unit 1 includes two flow path switching valves 20 and 30, a measuring tube 40, and a sample concentration unit 50, and the analysis unit 2 includes a column oven 92, a column 91 for analysis, and a detector 93.

  In the sample introduction unit 1, the first flow path switching valve 20 and the second flow path switching valve 30 are rotary 6-port 2-position valves each having six ports a to f or ports g to l. Under the control of the control unit 3, the connection state is alternatively switched to a connection state indicated by a solid line or a dotted line in FIG. 1. In the first flow path switching valve 20, the state indicated by the solid line in FIG. 1 corresponds to the load state in the present invention, and the state indicated by the dotted line corresponds to the injection state. Moreover, in the 2nd flow-path switching valve 30, the state shown by the continuous line in FIG. 1 is equivalent to the collection pipe short circuit state in this invention, and the state shown by the dotted line is equivalent to the collection pipe insertion state.

  A needle 10 for collecting sample gas is connected to the port a of the first flow path switching valve 20, and the needle 10 is arranged so that the tip thereof is located in the upper space (head space) of the sample container 11. Has been. A gas inlet 61 for introducing a gas for pressurizing the inside of the sample container 11 (a gas for pressurization) and a gas outlet 71 for discharging the sample gas are connected to the port b via a branch pipe T1. Yes. An electromagnetic valve SV2 is provided on the flow path from the branch pipe T1 to the gas inlet 61, and a pressure sensor 80 and an electromagnetic valve SV1 are provided on the flow path from the branch pipe T1 to the gas outlet 71. The port c is connected to the port k of the second flow path switching valve 30 via a measuring tube 40 having a predetermined volume. The port d is connected to a gas inlet 63 for introducing a carrier gas, and the port e is connected to the inlet end of the column 91 and the split flow path F4 via a branch pipe T2. The split flow path F4 is for discharging a part of the sample gas without sending it to the column 91, and a gas outlet 72 for discharging the sample gas is provided at the end thereof. The port f is connected to the port 1 of the second flow path switching valve 30.

  On the other hand, the collection pipe 51 of the sample concentration unit 50 is connected between the port g and the port j of the second flow path switching valve 30, and a purge gas to be described later is introduced into the port h via the electromagnetic valve SV3. And a gas outlet 73 for discharging the purge gas is connected to the port i. Here, the sample introduction unit 1 adopts a split method, but it is natural that a splitless method may be used.

  As the collection tube 51, a tube in which a predetermined adsorbent is applied to the inner surface of a hollow tube, a tube in which a predetermined adsorbent is filled, or the like can be used. In addition, as said predetermined adsorption agent, activated carbon, various resin, etc. can be used, for example. In addition to such a collection tube 51, the sample concentration unit 50 includes a cooling unit 52 for cooling the collection tube 51 and a heating unit 53 for heating the collection tube 51. The heating unit 53 can be configured by, for example, a heater or the like provided so as to be in contact with the collection tube 51, and the cooling unit 52 is provided in a refrigerant tube provided so as to be in contact with the collection tube 51, for example. It is possible to cool the collection tube 51 by circulating a refrigerant, or to cool the collection tube 51 with a Peltier element.

  In the sample introduction section 1, the flow path F1 connected to the port a of the first flow path switching valve 20 and the flow path F2 connected to the port d are the sample gas supply flow path and the carrier gas supply flow in the present invention, respectively. The flow path F3 from the port b to the gas outlet 71 corresponds to the exhaust flow path in the present invention. Further, the flow path F6 connected to the port h of the second flow path switching valve 30 corresponds to the purge gas supply flow path in the present invention, and the flow path F5 connected to the port i corresponds to the purge gas discharge flow path in the present invention. The analysis unit 2 corresponds to a gas analyzer in the present invention.

  The gas inlets 61 and 62 and the gas outlet 71 are connected to a pressure control unit (not shown), and the pressure of the gas flowing through the gas inlets 61 and 62 and the gas outlet 71 is controlled by the pressure control unit. On the other hand, the gas inlet 63 and the gas outlets 72 and 73 are controlled by a flow rate control unit (not shown), and the flow rate of the gas flowing through the gas inlet 63 and the gas outlets 72 and 73 is controlled by the flow rate control unit. The pressure control unit and the flow rate control unit may be electronically controlled or manually operated.

  The control unit 3 controls the opening / closing operation of the electromagnetic valves SV1 to SV3 of the sample introduction unit 1, the switching operation of the flow path switching valves 20, 30, the operation of the pressure control unit, the flow rate control unit, and the like, and the analysis unit 2 The operations of the column oven 92 and the detector 93 are controlled. The control unit 3 is embodied by a personal computer, for example, and controls the operation of each unit according to a predetermined control program, thereby executing sample introduction to the analysis unit 2 by the sample introduction unit 1 and analysis of the sample by the analysis unit 2 To do.

  The sample introduction part 1 according to the present embodiment is for introducing a sample gas by the headspace method. The head space method is a method in which a liquid sample (or solid sample) accommodated in the sample container 11 is heated, and the volatilized sample component is collected from the upper space in the container and introduced into the column 91. Moreover, the sample introduction part 1 which concerns on a present Example becomes a structure which can selectively perform any one of measurement mode, concentration mode, and precut mode as an operation mode at the time of sample gas introduction. Which operation mode is executed is designated in advance by the user. Hereinafter, the operation of the sample introduction unit 1 during the execution of each mode will be described. The solenoid valves SV1 to SV3 are closed unless otherwise specified.

1. Metering mode The metering mode is a mode in which the sample gas is weighed by the metering tube 40 and then introduced into the analysis column 91 in its entirety. When the measurement mode is executed, the following series of operations are performed in a state where the collection pipe 51 is short-circuited from the flow path of the sample gas and the carrier gas by always setting the second flow path switching valve 30 to the connection state indicated by the solid line. Do.

(i) Pressurization step First, the first flow path switching valve 20 is brought into a connected state indicated by a solid line, and the sample container 11 is heated to a predetermined temperature by a heating means (not shown) to be in a gas-liquid equilibrium state. Thereafter, the electromagnetic valve SV2 is opened, and the inside of the sample container 11 is pressurized by introducing a pressurizing gas from the gas inlet 61.

(ii) Step of introducing sample gas into measuring tube Subsequently, when the solenoid valve SV2 is closed and the solenoid valve SV1 is opened, the gas containing the sample component vaporized in the sample container 11 (sample gas) flows from the needle 10 to the flow path. It flows into F1 and flows into the measuring tube 40 through the first flow path switching valve 20 and the second flow path switching valve 30. At this time, a part of the gas flowing into the measuring pipe 40 is discharged from the gas outlet 71 through the first flow path switching valve 20, the branch pipe T1, and the flow path F3. During the above steps, the carrier gas flows from the gas inlet 63 to the column 91 through the flow path F2 → the first flow path switching valve 20 → the branch pipe T2.

(iii) Sample gas delivery step to the column After that, when the first flow path switching valve 20 is in the connection state indicated by the dotted line, the carrier gas supplied from the gas inlet 63 is flow path F2 → first flow path switching valve 20 It passes through the metering tube 40 → the second flow path switching valve 30 → the first flow path switching valve 20 → the branch pipe T 2 in this order and flows to the column 91. As a result, a predetermined amount of sample gas held in the measuring tube 40 is introduced into the column 91 together with the flow of the carrier gas. At this time, part of the carrier gas and the sample gas flowing out from the port e of the first flow path switching valve 20 and reaching the branch pipe T2 flows into the split flow path F4 at a predetermined split ratio and flows from the gas outlet 72. Discharged.

2. Concentration Mode Next, the operation when the concentration mode is executed will be described. The concentration mode is a mode in which the sample gas is concentrated by the sample concentration unit 50 and then introduced into the column 91.

(i) Pressurization process First, the first flow path switching valve 20 and the second flow path switching valve 30 are connected to each other as shown by the solid line, and then the electromagnetic valve SV2 is opened. 11 is heated and pressurized.

(ii) Sample component adsorption step Thereafter, the electromagnetic valve SV2 is closed, the second flow path switching valve 30 is switched to the connection state indicated by the dotted line, and the electromagnetic valve SV1 is opened. As a result, the sample gas in the sample container 11 passes through the needle 10 → the flow path F 1 → the first flow path switching valve 20 → the second flow path switching valve 30 in this order and flows into the collection tube 51. At this time, the collection tube 51 is cooled to a predetermined temperature by the cooling unit 52, and the sample component is adsorbed inside the collection tube 51 while the sample gas passes through the collection tube 51. The sample gas after the sample component is adsorbed flows in the order of the second flow path switching valve 30 → the measuring pipe 40 → the first flow path switching valve 20 → the branch pipe T 1 → the flow path F 3 and is discharged from the gas outlet 71. Is done.

(iii) Dry purge process In the sample component adsorption process described above, moisture in the sample gas is also adsorbed in the collection tube 51 together with the sample component to be analyzed, so that the moisture is fed into the column 91 during analysis. It is necessary to carry out a moisture removal process (dry purge) in advance so that there is no problem. In this dry purge step, the second flow path switching valve 30 is switched to the connection state indicated by the solid line and the electromagnetic valve SV3 is opened, so that the flow path from the gas inlet 62 through the collection pipe 51 to the gas outlet 73 is reached. Form. Accordingly, a purge gas such as dry helium gas passes through the flow path, and moisture in the collection pipe 51 is discharged from the gas outlet 73 together with the purge gas.

(iv) Step of Desorbing Sample Component and Sending to Column Subsequently, the first flow path switching valve 20 and the second flow path switching valve 30 are switched to the connection state indicated by the dotted line, and captured by the heating unit 53 at a predetermined timing. The collecting tube 51 is rapidly heated to desorb the sample component from the collecting tube 51. Thus, after the carrier gas supplied from the gas inlet 63 passes through the flow path F 2 → the first flow path switching valve 20 → the measuring pipe 40 → the second flow path switching valve 30 → the collection pipe 51, the second flow path The sample component that has flowed into the column 91 through the switching valve 30 → the first flow path switching valve 20 → the branch pipe T2 and desorbed from the collection pipe 51 by heating by the heating unit 53 enters the column 91 together with the carrier gas. be introduced.

3. Precut Mode Next, the operation when the precut mode is executed will be described. The precut mode in the present embodiment is a mode in which the sample gas collected in the measuring tube 40 is roughly separated by the collecting tube 51 and a part thereof is introduced into the column 91.

(i) Pressurization process First, the first flow path switching valve 20 and the second flow path switching valve 30 are connected to each other as shown by the solid line, and then the electromagnetic valve SV2 is opened. 11 is heated and pressurized.

(ii) Sample gas introduction step into the measuring tube Subsequently, the sample gas vaporized in the sample container 11 is measured by closing the electromagnetic valve SV2 and opening the electromagnetic valve SV1 in the same manner as in the measuring mode. 40.

(iii) Sample gas delivery step to the column Next, when the first flow path switching valve 20 and the second flow path switching valve 30 are switched to the connection state indicated by the dotted line, the carrier gas supplied from the gas inlet 63 is flow path. F2 → first flow path switching valve 20 → metering pipe 40 → second flow path switching valve 30 → collection pipe 51, and further, second flow path switching valve 30 → first flow path switching valve 20 → branch pipe. It flows into the column 91 through T2. Due to the flow of the carrier gas, the sample gas filled in the measuring tube 40 is swept away and flows into the collecting tube 51. At this time, the temperature of the collection tube 51 is room temperature (that is, the state in which neither the cooling by the cooling unit 52 nor the heating by the heating unit 53 is performed). Various components are separated for each component by interaction with the adsorbent inside the collection tube 51. The sample components thus separated are eluted from the collection tube 51 in the order of the low boiling point and introduced into the column 91 together with the carrier gas.

(iv) Precut Step After that, when a predetermined time set in advance (hereinafter referred to as “precut time”) has elapsed, the first flow path switching valve 20 and the second flow path switching valve 30 are brought into a state indicated by solid lines. Switch. As a result, the measuring tube 40 and the collecting tube 51 are short-circuited from the flow path of the carrier gas, and the carrier gas flows from the gas inlet 63 to the column 91 via the flow path F2 → the first flow path switching valve 20 → the branch pipe T2. It begins to flow. For this reason, the components remaining inside the collection tube 51 at this time are closed off from the carrier gas flow path without being introduced into the column 91. Therefore, the time at which the target component in the sample gas is introduced into the column 91 is obtained in advance by a preliminary experiment or the like, and the precut time is set so that the precut is performed at an appropriate timing after the time. Only the low boiling point component including the target component can be introduced into the column 91, and unnecessary high boiling point components can be cut off.

  In such a precut mode, it is desirable to set various conditions (precut time, carrier gas flow rate, etc.) so that the target component and unnecessary high-boiling components are sufficiently separated and sample introduction is completed in as short a time as possible. In the above example, the component separation by the collection tube 51 is performed in a state where the collection tube 51 is at room temperature, but the collection tube 51 is adjusted to a predetermined temperature by the cooling unit 52 and the heating unit 53. It is good also as what performs the component separation by this collection pipe | tube 51 above. This makes it possible to set more appropriate conditions. Further, since the cooling unit 52 and the heating unit 53 are conventionally provided in the sample concentration unit 50, it is not necessary to add new parts.

(v) Purge Step After performing the above-described precut step, the collection tube 51 is purged before the next sample is introduced, and the high boiling point component remaining in the collection tube 51 is discharged out of the system. In this purging step, the electromagnetic valve SV3 is opened while the first flow path switching valve 20 and the second flow path switching valve 30 are kept in the connection state indicated by the solid line, and the collection pipe 51 is further opened by the heating unit 53. Is heated to desorb high-boiling components from the collecting tube 51. Thereby, the purge gas such as helium gas supplied from the gas inlet 62 flows through the electromagnetic valve SV3 in the order of the second flow path switching valve 30 → the collection pipe 51 → the second flow path switching valve 30 → the gas outlet 73. Thus, the high boiling point component desorbed from the collecting tube 51 by heating by the heating unit 53 is discharged out of the system from the gas outlet 73 together with the purge gas.

  The best mode for carrying out the present invention has been described above using the embodiments. However, the present invention is not limited to the above embodiments, and modifications can be appropriately made within the scope of the gist of the present invention. It is. For example, in the above embodiment, the sample gas is introduced by the head space method, but the method of introducing the sample is not limited to this, and various methods can be adopted. 2 and 3 show a configuration example of a gas chromatograph provided with a gas sample introduction device by another sample introduction method.

  FIG. 2 shows a system in which a purge gas is blown into a sample liquid to forcibly drive out and collect volatile organic compounds and mold odors in water. In this example, there is no branch pipe T1, and the other end of the flow path connected to the gas inlet 61 is inserted into the sample container 11. Other configurations are the same as in the above embodiment. In the sample introduction apparatus having such a configuration, the sample liquid is bubbled (aeration process) in the above-mentioned “(i) Pressurization step” in any of the measurement mode, the concentration mode, and the precut mode. Specifically, the pressurizing gas is introduced from the gas inlet 61 and vented to the sample liquid by bringing the first flow path switching valve 20 into the connection state indicated by the solid line in FIG. 2 and opening the electromagnetic valve SV2. . As a result, volatile organic compounds and the like in the liquid are expelled into the upper space of the sample container 11 and the inside of the sample container 11 is pressurized. The subsequent operations are the same as in the above embodiment.

  FIG. 3 shows a system in which sample gas is collected by suction with a pump. The apparatus of the figure does not have a flow path for pressurizing the sample container (a flow path from the gas inlet 61 to the branch pipe T1 in FIG. 1), and the sample gas between the solenoid valve SV1 and the gas outlet 71. The configuration is the same as that of the above-described embodiment except that a pump 82 for sucking in and a mass flow controller 81 for controlling the flow rate at the time of suction are provided. When performing the measurement mode or the precut mode in the sample introduction apparatus having such a configuration, the “(ii) sample gas introduction step into the measurement tube” is performed without performing the above-mentioned “(i) pressurization step”. Do. At that time, the first flow path switching valve 20 and the second flow path switching valve 30 are set to the connection state indicated by the solid line in FIG. 3, the electromagnetic valve SV1 is opened, and the pump 82 is driven. As a result, the sample gas stored in the sample container (not shown) such as a sample bag is sucked through the flow path F1 connected to the port a of the first flow path switching valve 20, and passes through the measuring tube 40. It is discharged from the gas outlet 71. Further, when executing the concentration mode, the “(ii) sample component adsorption step” is performed without performing the “(i) pressurization step” described above. At this time, the first flow path switching valve 20 is set to the connection state indicated by the solid line in FIG. 3, the second flow path switching valve 30 is set to the connection state indicated by the dotted line, the electromagnetic valve SV1 is opened, and the pump 82 is To drive. Thereby, the sample gas accommodated in the sample container such as the sample bag is sucked through the flow path F1 connected to the port a of the first flow path switching valve 20, and passes through the collection pipe 51 and the measuring pipe 40. And is discharged from the gas outlet 71. Other operations are the same as in the above embodiment.

DESCRIPTION OF SYMBOLS 1 ... Sample introduction part 2 ... Analysis part 3 ... Control part SV1-3 ... Solenoid valve T1, T2 ... Branch pipe 10 ... Needle 11 ... Sample container 20 ... 1st flow-path switching valve 30 ... 2nd flow-path switching valve 40 ... Measuring tube 50 ... Sample concentration unit 51 ... Collecting tube 52 ... Cooling unit 53 ... Heating units 61, 62, 63 ... Gas inlet 71, 72, 73 ... Gas outlet 91 ... Column 92 ... Column oven 93 ... Detector

Claims (2)

A gas sample introduction device for introducing a sample gas into a gas analyzer,
a) a measuring tube having a predetermined volume;
b) a sample gas supply channel for introducing the sample gas into the measuring tube;
c) a carrier gas supply channel for introducing a carrier gas into the measuring tube;
d) an exhaust passage for discharging the gas that has passed through the measuring pipe to the outside;
e) a concentrating means comprising a collecting tube containing the adsorbent and concentrating the sample gas by a thermal desorption method;
f) A load state in which the metering tube is inserted between the sample gas supply channel and the exhaust channel, and the metering tube is inserted between the carrier gas supply channel and the gas analyzer. A first flow path switching valve for switching between the injected state,
g) In the load state or the injection state, a collection tube insertion state in which the collection tube is interposed between the sample gas supply channel and the measurement tube or between the measurement tube and the gas analyzer; A second flow path switching valve that switches between a collecting pipe short-circuit state that does not interpose the collecting pipe;
A gas sample introduction device characterized by comprising: h) a purge gas supply channel for introducing a purge gas into the collection tube;
i) a purge gas discharge passage for discharging the purge gas that has passed through the collection pipe to the outside;
And the second flow path switching valve is configured to interpose the collection pipe between the purge gas supply flow path and the purge gas discharge flow path when the collection pipe is short-circuited. The gas sample introducing device according to claim 1.

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