JP4840409B2 - Gas chromatograph - Google Patents

Description

  The present invention relates to a gas chromatograph, and more particularly to a gas chromatograph that concentrates and introduces a gas sample collected in a soft sample container.

As a method of introducing a concentrated sample in gas chromatography, a programmed temperature controlled vaporization method (Programmed Temperature Vaporization) is known, and a sample introduction device using this method is generally abbreviated as PTV.
The configuration and operation of the PTV are described as conventional technology in Patent Document 1, but will be briefly described below.

FIG. 5 shows the basic configuration of a gas chromatograph equipped with a conventional PTV.
In the figure, reference numeral 20 denotes a flow controller used for carrier gas flow rate control. 21 is a sample vaporizing chamber for PTV whose program temperature can be controlled, and has a sample introduction port 27 sealed with a septum 28 at the top, and a concentrating tube 24 is supported inside by a seal ring 25. In this case, the concentration tube 24 is generally configured by filling an adsorbent or the like into a glass tube called a liner inserted into the sample vaporizing chamber 21.
22 is a column that separates the measurement target substance sent from the sample vaporizing chamber 21 into each component, 23 is a detector that detects each separated component and outputs it as an electrical signal, and 26 is a split flow that branches from the sample vaporizing chamber 21. And is opened and closed by a split valve 29.
The seal ring 25 divides the internal space of the sample vaporizing chamber 21 into upper and lower portions, and the divided upper and lower spaces are communicated only through the concentration tube 24. Accordingly, both the carrier gas and the sample introduced into the upper space flow through the concentrating tube 24 to the lower space, and further to the column 22 and the split flow path 26 connected thereto.

The gas chromatograph with PTV configured as described above operates as follows.
The carrier gas is flow-controlled by the flow controller 20 and supplied to the sample vaporizing chamber 21, passes through the concentrating tube 24 provided therein, and further flows to the detector 23 through the column 22. When it is open, a part is discharged through the split channel 26.
In the sample concentration process, the liquid sample injected into the sample vaporizing chamber 21 through the septum 28 with a syringe (not shown) or the like from the sample introduction port 27 with the split valve 29 opened is vaporized and concentrated in the concentration tube 24. Here, the substance to be measured in the sample is collected and concentrated. The solvent vapor occupying most of the sample passes through the concentration tube 24 and is discharged through the split flow path 26.
In the analysis process, first, the split valve 29 is closed by a timer device or the like (not shown) at the timing when most of the solvent vapor is discharged, then the temperature of the sample vaporizing chamber 21 is rapidly raised, and the concentrating tube 24 inside thereof is connected. When heated, the concentrated measurement target substance is desorbed from the concentration tube 24 and introduced into the column 22, and each separated component is detected by the detector 23, whereby gas chromatography analysis is performed.
JP 2001-343374 A

Although the sample introduced into the PTV is mainly liquid as described above, a gas sample can be introduced as long as the pressure is higher than the internal pressure of the sample vaporizing chamber. However, for example, when analyzing odorous substances in the atmosphere, sample air is collected in a bag-like container (hereinafter referred to as a soft sample container) made of a polyvinyl fluoride resin film called a sample bag and analyzed. It is common to carry it back to the room for analysis, and the pressure of the sample in this case is almost atmospheric pressure. Therefore, it is difficult to introduce it into PTV. Conventionally, a dedicated concentration device is additionally provided, the target component is concentrated using this, and then transferred to a gas chromatograph for analysis. There wasn't.
This invention is made | formed in view of such a situation, and it aims at providing the gas chromatograph with PTV which can introduce sample gas directly from a soft sample container.

  In order to solve the above-mentioned problems, the present invention provides a gas chromatograph equipped with a PTV, wherein a soft sample container containing a sample gas is connected to a sample inlet of the PTV, and a pressure reducing means for reducing the pressure in the sample vaporizing chamber is provided. It connects via the split flow path branched from the sample vaporizing chamber. With such a configuration, even an atmospheric pressure sample collected in a soft sample container is sucked by a low pressure means such as a suction pump and introduced into the PTV, whereby concentration and analysis can be performed consistently.

  Since the present invention is configured as described above, it is possible to perform the concentration and analysis by directly introducing the atmospheric pressure sample collected in the soft sample container, and conventionally, a separate concentration device was interposed. Compared to the case, the configuration of the apparatus is simplified, and the control thereof can be integrated and automated by setting in the gas chromatograph. In addition, since concentration to analysis can be performed consistently within the gas chromatograph, sample loss due to adsorption to the piping and cold spots associated with sample transfer between devices is minimized, and highly accurate analysis results are obtained. Can be obtained.

  The gas chromatograph apparatus provided by the present invention has the following characteristics. That is, the first feature is that the soft sample container is connected to the sample introduction port of the PTV, and the second feature is that a low pressure reducing means such as a suction pump is provided in a split flow path branched from the sample vaporizing chamber. It is the point which comprised so that it might connect. Therefore, the basic configuration of the best mode is a gas chromatograph apparatus having these configurations.

FIG. 1 shows an embodiment of the present invention. In the figure, the same components as those in the conventional example shown in FIG.
This embodiment differs from the conventional example shown in FIG. 5 in that the soft sample container 11 is connected to the sample inlet 27 via the electromagnetic valve 13, and the suction pump 12 is connected to the end of the split flow path 26. Is a point. Here, the soft sample container 11 is a bag-like container made of, for example, a polyvinyl fluoride resin film, and the structure for connecting it to the sample inlet 27 is, for example, as shown in FIG. 3 (the description of FIG. 3 will be described later). In addition, a vacuum pump is used as the suction pump 12.

The operation process of analysis by the apparatus of this embodiment will be described below in order.
(1) As a state before analysis, the carrier gas is set to a predetermined flow rate for analysis, the temperature of the sample vaporizing chamber 21 is set to a predetermined temperature at the time of concentration (for example, a low temperature below room temperature), and the split valve 29 and the electromagnetic valve 13 are Both are closed and the suction pump 12 is stopped.
(2) The carrier gas is stopped by the flow controller 20, or the flow rate is reduced to about 1 ml / min or less.
(3) Open the split valve 29, operate the suction pump 12, and then open the solenoid valve 13.
(4) The sample gas in the soft sample container 11 is sucked into the sample vaporizing chamber 21, passes through the concentration tube 24, and is discharged through the split flow path 26. During this time, the substance to be measured in the sample gas is collected in the concentration tube 24.
(5) After suctioning for a predetermined time, the suction pump 12 is stopped and the solenoid valve 13 is closed.
(6) The carrier gas having a predetermined analysis flow rate is supplied by the flow controller 20 and the split valve 29 is closed.
(7) The temperature of the sample vaporizing chamber 21 is rapidly raised by a program temperature controller (not shown). As a result, the concentration tube 24 is heated, and the collected substance to be measured is desorbed from the concentration tube 24 and introduced into the column 22 for gas chromatography analysis.

  In this way, the atmospheric pressure sample gas stored in the soft sample container 11 can be taken into the gas chromatograph with PTV, concentrated and analyzed. All the above operations can be automatically performed by using a program timer (not shown) or the like. Modern gas chromatographs with built-in computers usually have a timer function, so using this makes it easy to automate.

  Note that the electromagnetic valve 13 in FIG. 1 can be replaced with a check valve that allows gas to flow one-way from the soft sample container 11 toward the sample vaporizing chamber 21. When the check valve is used, the opening / closing operation of the valve is not necessary, so that the operation process can be further simplified. Further, when it is not necessary to automate, the electromagnetic valve 13 in FIG. 1 may be replaced with a manual on-off valve. That is, the electromagnetic valve 13 in FIG. 1 can be replaced with various valve mechanisms that generally open and close the flow path.

FIG. 2 shows another embodiment of the present invention. This embodiment is different from the first embodiment shown in FIG. 1 only in that it does not have a solenoid valve 13 or the like, and all other components having the same reference numerals as those in FIG. 1 are the same as those in FIG. I will omit the explanation again.
In this embodiment, since there is no valve between the soft sample container 11 and the sample vaporizing chamber 21, when the carrier gas is supplied to the sample vaporizing chamber 21, the pressure of the carrier gas is applied to the soft sample container 11, and the soft sample is The container 11 may be damaged. For this reason, it is necessary to attach the soft sample container 11 only when the sample is inhaled and to remove it from the sample inlet 27 while the carrier gas is flowing. Reference numeral 15 denotes a lead tube.

Attachment / removal of the soft sample container 11 to / from the sample introduction port 27 is performed as follows.
FIG. 3 shows an example of the structure around the sample inlet 27 in the present embodiment. In FIG. 3, the sample vaporizing chamber 21 includes a vaporizing chamber cylinder 17, a septum nut 16 screwed into the top thereof, and a sample. It is located directly under the introduction port 27 and is composed of an O-ring 18 and the like pressed by the septum nut 16. The leading end of the lead tube 15 communicating with the soft sample container 11 is inserted into the vaporization chamber cylinder 17 through the O-ring 18 from the sample introduction port 27, and the sample vaporization chamber 21 is kept airtight by tightening the septum nut 16. Be drunk.
When attaching or removing the soft sample container 11, the septum nut 16 may be loosened and the lead tube 15 may be inserted or removed. By inserting a round bar-like plug (not shown) having the same outer shape as the lead tube 15 into the trace of the lead tube 15 being removed and tightening with the septum nut 16, the airtightness of the sample vaporizing chamber 21 can be maintained.

The operation process in this embodiment is as follows.
(1) As a state before analysis, a plug is inserted into the sample inlet 27, the carrier gas is set to a predetermined flow rate for analysis, and the temperature of the sample vaporizing chamber 21 is set to a predetermined temperature at the time of concentration (for example, a low temperature below room temperature). The split valve 29 is closed and the suction pump 12 is stopped.
(2) Stop the carrier gas with the flow controller 20 or reduce the flow rate to about 1 ml / min or less, and then connect the soft sample container 11 containing the sample gas to the sample introduction port 27.
(3) The split valve 29 is opened and the suction pump 12 is operated.
(4) The sample gas in the soft sample container 11 is sucked into the sample vaporizing chamber 21, passes through the concentration tube 24, and is discharged through the split flow path 26. During this time, the substance to be measured in the sample gas is collected in the concentration tube 24.
(5) After suctioning for a predetermined time, the suction pump 12 is stopped, the soft sample container 11 is removed, and a plug is inserted into the sample inlet 27 instead.
(6) The carrier gas having a predetermined analysis flow rate is supplied by the flow controller 20 and the split valve 29 is closed.
(7) The temperature of the sample vaporizing chamber 21 is rapidly raised by a program temperature controller (not shown). Thus, the substance to be measured collected by heating the concentration tube 24 is desorbed from the concentration tube 24 and introduced into the column 22 for gas chromatography analysis.

  In this embodiment, as described above, the workability is not good because it takes time and labor to attach and remove the soft sample container 11, but it has a necessary and sufficient function for concentrating and analyzing the sample gas in the soft sample container 11. I have.

FIG. 4 shows another embodiment of the present invention. The figure shows only the part relating to the soft sample container 11 and the sample vaporizing chamber 21, and the configuration of the peripheral part not shown is the same as that shown in FIG.
In this embodiment, the sample introduction port 27 is sealed with a septum 28 as in the conventional case, and a tubular needle 14 (for example, an injection needle) attached to the mouth of the soft sample container 11 is pierced into the septum 28, so that the soft sample container 11 And the sample vaporizing chamber 21 are connected. In this case, since there is no valve between the soft sample container 11 and the sample vaporization chamber 21 as in the second embodiment, it is necessary to attach and remove the soft sample container 11 in the operation process. Therefore, the workability is improved as compared with the second embodiment.
The operation process is the same as in the second embodiment (however, an operation relating to the plug is unnecessary).

In the first to third embodiments, the suction pump 12 is not limited to a vacuum pump, and any diaphragm type, piston type, or other types of pumps can be used as long as they have a required suction force. For example, not only the pump but also a low pressure means (for example, a low pressure chamber) that can be connected to the sample vaporizing chamber 21 via the split flow channel 26 and can reduce the pressure can be replaced.

  The present invention can be used, for example, for gas chromatographic analysis of trace components in the atmosphere.

It is a figure which shows one Example of this invention. It is a figure which shows the other Example (Example 2) of this invention. It is a figure which shows the detailed structure of Example 2. FIG. It is a figure which shows the other Example (Example 3) of this invention. It is a figure which shows the example of a conventional structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Soft sample container 12 Suction pump 13 Electromagnetic valve 14 Tubular needle 15 Lead tube 16 Septum nut 17 Vaporization chamber cylinder 18 O-ring 20 Flow controller 21 Sample vaporization chamber 22 Column 23 Detector 24 Concentration tube 25 Seal ring 26 Split flow channel 27 Sample Inlet 28 Septum 29 Split valve

Claims (3)

Has a sample inlet, provided inside concentrated tube for collecting concentrated sample components, comprising a programmable temperature-controllable sample vaporizing chamber for vaporizing trapped concentrated sample components, the carrier gas is the sample introduction port A gas chromatograph in which the flow path is configured to flow through the concentrating tube with the sample introduced from and then to the flow path leading to the detector through the column and the split flow path branched from the sample vaporization chamber The gas chromatograph is characterized in that a soft sample container containing a sample gas is directly connected to the sample introduction port, and a low pressure reducing means for reducing the pressure in the sample vaporizing chamber is connected via the split flow path. 2. The gas chromatograph according to claim 1, wherein the low pressure means is constituted by a suction pump connected to the split flow path. The gas chromatograph according to claim 1, wherein the soft sample container is directly connected to the sample inlet through a valve mechanism for opening and closing the flow path.

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