JP2016114456A - Headspace autosampler and gas analysis system using the same - Google Patents

Abstract

A headspace autosampler capable of avoiding the use of a sample gas flow path switching unit or a branching element, selecting an analysis line, and simultaneously guiding sample gas from the same sample container to different analysis lines. I will provide a. SOLUTION: A plurality of needles 3a, 3b that can be inserted into a sample container 1 are provided, and each needle is connected to an individual sampling line A, B respectively, and sample gas is simultaneously or selectively supplied to each line A, B. By allowing the gas to be introduced, the sample gas is guided to a desired line without using the flow path switching unit or the branching element, and the occurrence of adsorption or decomposition in the sampling line is suppressed. [Selection diagram] Figure 1

Description

  The present invention relates to a headspace autosampler for supplying a sample gas to a gas analyzer such as a gas chromatograph, and a gas analysis system using the headspace autosampler.

  One of analysis methods in gas chromatograph (GC) is a head space analysis method. In this head space analysis method, a solid or liquid sample is placed in a sample container such as a vial, and the sample container is heated at a constant temperature for a certain period of time, whereby a solid or liquid sample is placed in the upper space (head space) of the sample container. A gas such as a volatile organic compound generated or contained from a liquid sample is collected and introduced into a gas chromatograph or a gas chromatograph mass spectrometer (GC / MS). The operation of the headspace autosampler that automatically samples the sample gas, sample preparation, and the like are as exemplified below.

  First, a solid or liquid sample is placed in a vial and sealed. This stopper is made of a flexible material, and a septum is generally used in which a fluorine resin sheet is attached to the surface of silicon rubber or the like. After mounting the septum on the vial, the metal cap is caulked with a dedicated tool so that the headspace gas does not escape from the vial.

  The headspace autosampler transfers the volatile organic compound from the sample to the headspace by heating the vial prepared as described above at a constant temperature for a predetermined time. Next, a hollow needle is inserted into the septum of the vial, and an inert gas such as helium gas is supplied into the vial and pressurized (if the headspace gas is near or above atmospheric pressure) In some cases, the inside of the vial is not pressurized). Next, the supply of the pressurizing gas is stopped, and a certain amount of pressurized headspace gas is withdrawn from the vial in the opposite direction through the same needle, and directly introduced into the GC or GC / MS inlet or separation column. To do. In a normal headspace autosampler, by setting a plurality of vials each enclosing a sample, each of these vials is automatically moved and positioned at the needle insertion position. Headspace gas is sampled and used for analysis (see, for example, Patent Document 1).

  There are gas tight syringe method, pressurized injection method, loop method, etc. as a method of extracting a certain amount of gas, but in any method, there is a difference in extracting a head space gas by inserting a hollow needle into a vial. Absent. Then, the sampled gas is guided to the GC or GC / MS inlet through the sampling line, and flows to the line formed through the column and the detector.

  Here, the sampled gas has a trap tube on the sampling line as shown in FIG. 3 in the case where, for example, the loop method shown in FIG. There are cases where unnecessary components such as water vapor contained in the sample gas are removed.

  To explain these, the trap system of FIG. 2 is used to collect the head space gas of the vial 201 enclosing the sample. In this example, after the needle 202 is inserted into the septum 203 located at the top of the vial 201, With the valves 204 and 205 opened and the valve 206 closed, a helium gas serving as a carrier gas and a pressurized gas is introduced into the vial 201 through the loop 207 to pressurize the inside. Then, the head space gas is introduced into the loop 207 by closing the valve 204 and opening only the valve 205. Next, the valve 205 is closed, the valves 204 and 206 are opened to introduce helium gas into the loop 207, and the headspace gas previously introduced into the loop 207 is supplied to the GC.

  On the other hand, in the system having the trap tube shown in FIG. 3, a vial 201 containing a sample is prepared in the same manner as described above, and the needles 202 are inserted into the septum 203 at the top of the vial 201 and the valves 204 and 205 are opened. With 206 closed, helium gas is introduced into the vial 201 through the trap tube 301 and the inside thereof is pressurized. Thereafter, the head space gas is introduced into the trap tube 301 by closing the valve 204 and opening only the valve 205. After repeating this operation once or a plurality of times, the valve 205 is closed, the valves 204 and 206 are opened, helium gas is introduced into the trap pipe 301, and unnecessary components such as moisture in the trap pipe 301 are removed and concentrated. Led headspace gas to GC.

  FIG. 4 shows an example of a gas sampler based on the loop system provided with a trap function. In this example, each port of the multi-port valve 401 is connected to both ends of the loop 402, both ends of the trap tube 403, a tube 406 communicating with the needle 405 inserted into the vial 404 containing the sample, a carrier gas introduction tube 407, A pressurized gas introduction pipe 408 or the like is connected, and pressurized gas is introduced into the vial 404 through the needle 405 by driving the multi-port valve 401 and an opening / closing valve provided at an appropriate position, and the inside is added. After the pressure is applied, sampling based on a normal loop method in which a head space gas is introduced into the loop 402 through the needle 405, a carrier gas is introduced into the loop 402, and the internal head space gas is led to the GC, The operation of introducing the measured headspace gas into the loop 402 into the trap tube 403 is performed once or After repeating several times, and by introducing a carrier gas into the trap pipe 403, allowing sampling at trapping mode leading to enrichment headspace gas to GC.

JP 2012-018095 A

  By the way, when analyzing samples, it may be necessary to select whether or not to concentrate using a trap tube for each sample set in the headspace autosampler, or to measure with a different detector or column. is there. In such a case, conventionally, the sampled gas is switched by a valve or the like to flow to a desired line. For example, when the sample gas is concentrated, in the apparatus configuration illustrated in FIG. 4, the flow path of the multiport valve 401 is appropriately switched to guide the sample gas to a line where the trap tube 403 is provided. In addition, when the column is switched, the flow path is switched by a valve before the column flows. Furthermore, in switching the detector, the flow path is switched by a valve or the like after the column.

  In any of the above cases, it is necessary to provide a flow path switching unit such as a valve or a Dean switch on the flow path of the sample gas. The flow path switching unit causes adsorption and decomposition of the gas flowing through the flow path, and switching near the column outlet causes the spread of the chromatogram peak.

  Furthermore, conventionally, when measuring the same sample with or without concentration, or when detecting with different columns and detectors, the same sample is measured multiple times, or the sampled gas is branched to It was necessary to make it flow in the line. As for the branching of the sample gas, it is necessary to use a branching element that causes adsorption and decomposition as in the case of the flow path switching unit, and there is a problem that it takes time to perform measurement multiple times.

  The present invention has been made in view of such circumstances, avoids the use of a sample gas flow path switching unit and a branch element as much as possible, allows selection of an analysis line, and allows sample gas in the same container to be used. The challenge is to provide a headspace autosampler that can simultaneously lead to different analysis lines and a gas analysis system using it.

  In order to solve the above problems, the headspace autosampler of the present invention has a needle penetrating the sealing member in an upper space in a sample container whose top is sealed by a sealing member made of a flexible material. The headspace sampler that inserts, collects the sample gas in the upper space and sends it to the analyzer is equipped with a plurality of needles, each of which can be selectively inserted in whole or in part into one sample container And each of these needles is connected to an individual sampling line, and is configured to supply a sample gas to each of the sampling lines.

  Here, in the headspace autosampler of the present invention, the plurality of sampling lines include both a line provided with a trap for removing unnecessary components in the sample gas and a line not provided with a trap. (Claim 2) can be preferably employed.

Further, in the headspace autosampler of the present invention, in addition to the plurality of needles connected to each of the sampling lines, the headspace autosampler includes a pressure line through which a gas for pressurizing the sample container flows, and is connected to the pressure line A needle is simultaneously inserted into one sample container together with at least one needle connected to the sampling line, and the sample gas is introduced through the other needle while introducing the pressurizing gas into the sample container from the pressure line. Can be configured to be supplied to the sampling line.
On the other hand, the gas analysis system of the present invention is characterized in that an individual gas analyzer is connected to each sampling line of the headspace autosampler having any one of the above-described configurations.

  The present invention provides a plurality of needles, holds all or a selected part of each needle so that it can be inserted into one sample container, and connects each needle to a dedicated sampling line. It is something to be solved.

  That is, by inserting all or part of a plurality of needles each connected to a dedicated sampling line into one sample container and sampling the headspace gas, the same sample gas can be obtained by a plurality of analysis methods. The analysis can be performed simultaneously or under an optional analysis method.

  For example, as in the invention according to claim 2, sampling is performed without using a flow path switching unit or a branch element by providing a sampling line leading to the gas analyzer with different presence or absence of a trap tube. The method of concentrating the sample gas and leading it to the gas analyzer and the method of guiding the sample gas to the gas analyzer without concentrating can be executed simultaneously or selectively.

  Further, as in the invention according to claim 4, by constructing a system in which different gas analyzers are connected to the sampling lines communicating with the respective needles, sample gases sampled from the same sample container can be detected in different columns or detections. Gas analysis using a vessel can be performed simultaneously or selectively.

  The invention according to claim 3 applies the idea of the present invention of inserting a plurality of needles into one sample container so that introduction of gas for pressurizing the sample container and derivation of headspace gas can be performed simultaneously. Is. That is, conventionally, the introduction of the pressurized gas into the sample container and the derivation of the headspace gas are sequentially performed with one needle, but in the invention according to claim 3, a plurality of needles are inserted into the sample container. One of them is used for introducing pressurized gas and the other needle is used for deriving headspace gas. As a result, the headspace gas can be derived simultaneously with the introduction of the pressurized gas.

  According to the present invention, a plurality of needles are connected to dedicated lines, respectively, and a part thereof is inserted simultaneously or selectively into the sample container. Without using it, the sample gas can be guided to the line according to the analysis purpose, and it is possible to suppress the adsorption and decomposition of the sample gas and the spread of the peak after the column separation.

The schematic diagram which shows the principal part structure of embodiment of this invention. Explanatory drawing of the sampling method of the head space gas by a loop system. Explanatory drawing of the sampling method which concentrates head space gas with a trap pipe. Explanatory drawing of the sampling line which enabled selection of the possibility of concentration in the sampling in a trap pipe.

  Hereinafter, an embodiment of the present invention will be described with reference to FIG. FIG. 1 schematically shows a main configuration of an embodiment of the present invention, and shows an example in which a plurality of needles are simultaneously inserted into one vial.

  A vial 1 containing a solid or liquid sample has its top sealed with a septum 1a, and heated by a heating device 2 at a certain temperature for a certain time, so that the head space 1b of the vial 1 becomes a sample gas. Will be filled.

  In the present embodiment, three needles 3 a, 3 b, 3 c are arranged above the vial 1, and the respective needles 3 a, 3 b, 3 c are fixed to each other by the needle holder 4. . The entire three needles 3a, 3b, 3c including the needle holder 4 are moved up and down with respect to the vial bottle 1 by a vertical movement mechanism (not shown). At the time of sampling, the needles 3 a, 3 b, 3 c pierce the septum 1 a at the top of the vial 1 by moving downward from the position of FIG. 1, and the tip reaches the head space 1 b of the vial 1. Become.

  The needles 3a, 3b, 3c are connected to dedicated lines A, B, C via dedicated pipes 5a, 5b, 5c and on-off valves 6a, 6b, 6c, respectively.

  The line A is a line in which the three-way valve 7, the sample loop 8, the on-off valve 9, the three-way valve 10, the trap 11, and the on-off valve 12 are arranged in this order, and is a loop type sampling line having a trap function. As shown in the figure, a carrier gas source 13 is connected to one port of the three-way valve 7, a GC 14 is connected to one port of the three-way valve 10, and the on-off valve 12 is connected to the carrier gas source 13. Has been.

  Line B is a line in which a three-way valve 15, a sample loop 16, and an on-off valve 17 are arranged. A carrier gas source 13 is connected to one port of the three-way valve 15, and a GC 18 is connected via the on-off valve 17. It is connected. Line B is a sampling line based on a loop system that does not concentrate the sample gas.

  The line C is a line for pressurizing the inside of the vial bottle 1, and a pressurized gas source 19 such as helium gas, which is the same as the carrier gas, is connected through an on-off valve 6c.

  In the above embodiment, for example, when the sample gas is concentrated using the line A for analysis, the needles 3a, 3b, 3c are inserted into the vial 1 and the on-off valve 6a of the line A is opened to open the line B. Open / close valve 6b is closed and line C open / close valve 6c is opened. At this time, the three-way valve 7 of the line A is in a state where the on-off valve 6a and the sample loop 8 communicate with each other, and the on-off valve 9 is closed. Thereby, as the pressure in the vial 1 increases, the sample gas existing in the head space 1b is introduced into the sample loop 8 of the line A through the needle 3a. Further, by closing the on-off valve 6c when the inside of the vial 1 reaches a certain pressure by the pressurized gas from the line C, a certain amount of sample gas is measured in the sample loop 8.

  Next, the on-off valve 6a is closed, and the on-off valve 9 is opened with the carrier gas source 13 and the sample loop 8 communicating with the three-way valve 7. Further, the on-off valve 9 and the trap pipe 11 are communicated with the three-way valve 10 and the on-off valve 12 is closed. Thereby, the sample gas in the sample loop 8 is sent into the trap tube 11 by the carrier gas, and unnecessary components are removed.

  After the above operation is repeated once or a plurality of times as necessary, the on-off valve 9 is closed, the trap pipe 11 and the GC 14 are in communication with the three-way valve 10, the on-off valve 12 is opened, and the carrier gas is trapped. 11 is introduced. Thereby, the sample gas in the trap tube 11 is introduced into the GC 14, and the concentrated sample gas is analyzed.

  On the other hand, when the sample gas is used for analysis without being concentrated using the line B, the needles 3a, 3b, 3c are inserted into the vial bottle 1 in the same manner as described above, and the open / close valve 6a of the line A is closed to open / close the line B. The valve 6b is opened, and the open / close valve 6c of the line C is opened. At this time, the on-off valve 6b and the sample loop 16 are communicated with the three-way valve 15 in the line B, and the on-off valve 17 is closed. As a result, the pressurized gas is introduced from the pressurized gas source 19 into the vial 1 to pressurize the inside, and when the pressure reaches a certain level, the on-off valve 6c is closed, so that the needle 3b is opened as described above. The sample gas is introduced into the sample loop 16 of the line B and metered.

  Next, the on-off valve 17 is opened, and the carrier gas source 13 and the sample loop 16 are in communication with the three-way valve 15, whereby the sample gas in the sample loop 16 is introduced into the GC 18 and concentrated. No sample gas analysis is performed.

  Further, in the above embodiment, when the sample gas in the vial 1 is performed both with and without concentration, both the on-off valves 6a and 6b of the line A and the line B are opened, and the line C is opened. The pressurized gas is introduced into the vial 1 and pressurized. As a result, the sample gas is introduced into both lines A and B, and the same operation as described above is performed in parallel in each of lines A and B, whereby analysis with and without concentration can be performed simultaneously.

  The points to be particularly noted in the above-described embodiments are that when the sample gas is concentrated and analyzed using the trap function and when the analysis is performed without concentration, the flow of a multi-port valve or the like as in the prior art is used. This is the point that only the operation of the on-off valves 6a and 6b is performed without using the path switching means, whereby the adsorption and decomposition of the sample gas can be suppressed.

  Here, in the above embodiment, an example in which the sampling line (line A) provided with the trap tube and the sampling line (line B) not provided are respectively connected to the corresponding needles has been shown. Of course, it is possible to adopt a method of use in which each needle communicates with a line having a different GC column, or each needle communicates with a GC having a different detector.

  In the above embodiment, an example in which a plurality of needles 3a, 3b, and 3c are simultaneously inserted into one vial 1 has been shown. Instead, an individual moving mechanism is provided for each needle, One needle can be used, or only a plurality of needles can be inserted into one vial.

  The number of needles that can be inserted into one vial can be set to an arbitrary number within a limited range in terms of space.

  Furthermore, in the above embodiment, although the example which provided the needle 3c for exclusive use for pressurizing the inside of the vial bottle 1 and the line 5c connected to it was shown, this invention is not limited to this, Each needle is also used for sampling and pressurization, and a pressurized gas source is connected to each of the lines through which these needles communicate. After pressurizing the inside of the vial as in the past, the pressurization is stopped. The sample gas may be introduced into the corresponding line.

DESCRIPTION OF SYMBOLS 1 Vial bottle 1a Septum 2 Heating device 3a, 3b, 3c Needle 4 Needle holder 5a, 5b, 5c Pipe 6a, 6b, 6c On-off valve 7 Three-way valve 8 Sample loop 9 On-off valve 10 Three-way valve 11 Trap pipe 12 On-off valve 13 GC (Line A)
14 Three-way valve 15 Sample loop 16 On-off valve 17 GC (Line B)

Claims (4)

A needle is inserted through the sealing member into the upper space in the sample container whose top is sealed with a sealing member made of a flexible material, and the sample gas in the upper space is collected and sent to the analyzer. In the headspace sampler
A plurality of needles, each of which is held in a sample container so that all or a part thereof can be selectively inserted, and each of these needles is connected to an individual sampling line, A headspace autosampler configured to supply a sample gas to a sampling line.   2. The headspace auto according to claim 1, wherein the plurality of sampling lines include both a line provided with a trap for removing unnecessary components in the sample gas and a line not provided with a trap. Sampler.   In addition to the plurality of needles connected to each of the sampling lines, a pressure line through which gas for pressurizing the sample container flows is provided, and the needle connected to the pressure line is at least one connected to the sampling line. It is configured to be simultaneously inserted into one sample container together with one needle, and to supply the sample gas to the sampling line through the other needle while introducing the pressurizing gas from the pressurizing line into the sample container. The headspace autosampler according to claim 1, wherein the headspace autosampler is provided.   A gas analysis system, wherein an individual gas analyzer is connected to each sampling line of the headspace autosampler according to any one of claims 1 to 3.

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