JPH08313507A - Sample injection port for gas chromatograph of septum purge type - Google Patents

Abstract

PURPOSE: To provide a sample injection port for gas chromatograph of septum purge type for carrying out a reliable sample analysis without causing any ghost peak. CONSTITUTION: A sample injection port is provided with a sample vaporization room 12 for vaporizing a sample by increasing the temperature and maintaining it at a constant temperature. The sample injection port for gas chromatograph feeds the vaporized sample to a column for analysis by a carrier gas 30 which is supplied from a carrier gas port pipe 8. A spherical body 18 which is capable of moving within a septum gas contact room 17 is provided, the spherical body 18 is used to close and open the entrance of the sample injection passage 16, and septum purge channels 20 and 21 which are independent of the carrier gas passage 19 are provided, and a carrier gas for washing the injection port septum 6 is allowed to flow in one direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of a sample injection port for a gas chromatograph that sends a vaporized sample to an analytical column, and the gas contact surface of a diaphragm for isolating the sample from the outside is washed with a carrier gas. The present invention also relates to a septum purge type sample inlet for a gas chromatograph, which prevents a component generated from a diaphragm when the temperature of the sample is raised from flowing toward the analytical column.

[0002]

2. Description of the Related Art A sample vaporization chamber for evaporating a sample by raising the temperature of the sample and keeping it at a constant temperature is provided, and a sample inlet for a gas chromatograph for sending the vaporized sample to an analytical column is constructed. In some cases, a septum (diaphragm) is provided at the inlet of the sample injection passage leading to the sample vaporization chamber to isolate the inside from the outside. Silicon rubber is usually used as the material of the septum, and the sample injection needle can be inserted into the sample vaporization chamber during sample injection. If the temperature of the sample inlet of such a configuration is set low, vaporization of the components of the septum can be avoided, but on the other hand, the sample to be measured does not vaporize, or even if it vaporizes, the sample will be immediately around the septum. Since the component of (1) adheres, actual analysis is impossible. Therefore, normally, the temperature of the sample injection port as described above is raised to a certain extent for use.

However, if the temperature of the sample injection port is raised to some extent, the temperature around the septum also rises, and ghost peaks due to the silicone rubber which is a component of the septum increase. This is because the silicon rubber begins to vaporize at a temperature of about 200 ° C. or higher. for that reason,
When heating the sample for analysis by gas chromatography,
A method called septum purge in which the gas contact surface of the septum is cleaned with the carrier gas used to transfer the sample and the gas after cleaning is discharged to the outside of the device is generally used (hereinafter, septum purge Formula).

Although not a septum purge type, there is provided a chamber in which a sphere can move between the sample vaporization chamber and the septum.
A sample injection port of a system in which the sample injection passage is closed by a sphere except when the sample is injected, and the sphere is moved to open the sample injection passage when the sample is injected is disclosed in JP-A-51-107889.
No. 6,086,045.

[0005]

In the above-mentioned general septum purge type sample injection port, it is possible to suppress the components generated from the septum from flowing into the analytical column to some extent, and to a certain extent, a ghost peak is generated. However, the passage of the carrier gas for cleaning the septum and the septum is not isolated, and the carrier gas only contacts the gas contact surface of the septum. Therefore, the silicone rubber component generated in the septum enters the sample vaporization chamber and is condensed at the tip of the analytical column during cooling of the column constant temperature bath, and enters the column at the next temperature rise and is contained in the measurement sample. There is a high possibility that a non-existent component will be detected and become a ghost peak. In particular, when a highly sensitive amplification is carried out by a gas chromatograph using a capillary column for observation, this ghost peak appears remarkably. Therefore, it becomes impossible to perform highly reliable sample analysis.

On the other hand, the septum purge type is not used
According to the conventional technique disclosed in Japanese Patent Laid-Open No. 107889,
It is possible to prevent the silicone rubber component generated in the septum from entering the sample vaporization chamber by closing the sample injection passage with a sphere except when injecting the sample, but the sample injection passage was opened by moving the sphere during sample injection. At times, it is inevitable that the silicone rubber component from the septum enters the sample vaporization chamber. As a result, a ghost peak appears as in the case of the above-mentioned general septum purge method, and therefore it becomes impossible to perform highly reliable sample analysis.

An object of the present invention is to provide a septum purge type sample inlet for a gas chromatograph capable of performing highly reliable sample analysis without the appearance of ghost peaks.

[0008]

In order to achieve the above object, according to the present invention, a sample vaporization chamber for heating and vaporizing a sample and sending it to a column and a sample injection passage inlet leading to the sample vaporization chamber are provided. And a septum capable of penetrating a sample injection needle at the time of sample injection, and the gas vaporization of the sample at the septum purge type gas chromatograph sample injection port where the gas contact surface of the septum is washed with a carrier gas and discharged to the outside of the device. A septum purge type flow path, which is provided independently of the passage of the carrier gas to the chamber, and has a septum purge passage for flowing the carrier gas for cleaning in one direction with respect to the gas contact surface of the diaphragm. A sample inlet for a gas chromatograph is provided.

In the septum purge type gas chromatograph sample injection port, preferably, the chamber is provided between the sample vaporization chamber of the sample injection passage and the diaphragm, and the sample injection passage is provided except when the sample is injected. And a sphere capable of moving inside the chamber so as to open the sample injection passage when the sample is injected.

In the above, preferably, the sphere is installed so that its center is located at a position displaced from the approach path of the sample injection needle by a distance of 1/3 or less of the diameter of the sphere except when the sample is injected, Moreover, when the sample is injected, it can be moved by the sample injection needle so as to open the sample injection passage.

[0011]

The sample injection port of the present invention constructed as described above is heated to vaporize the sample and is maintained at a certain temperature. Then, the sample vaporized in the sample vaporization chamber is transferred to the analytical column by the carrier gas supplied from the dedicated passage. At this time, the gas contact surface of the septum is also cleaned with the carrier gas, but the carrier gas for cleaning the septum passes through the septum purge flow path provided independently of the carrier gas passage to the sample vaporization chamber. The carrier gas after cleaning, which is caused to flow in one direction with respect to the gas contact surface of the septum and contains the vaporized septum component, is discharged to the outside of the apparatus.

As described above, the septum purge flow path independent of the passage to the sample vaporization chamber is provided, and the carrier gas is caused to flow in one direction with respect to the gas contact surface of the septum, so that after the cleaning including the vaporized septum component is completed. Carrier gas is unilaterally exhausted out of the apparatus and does not enter the sample vaporization chamber. On the other hand, since a pure carrier gas that does not contact the septum flows at a constant rate in the sample vaporization chamber,
No gas generated from the septum is mixed in the analytical column. As a result, ghost peaks do not appear, which can contribute to the improvement of analysis reliability.

A chamber is provided between the sample vaporization chamber and the diaphragm of the sample injection passage, and the sphere is movable inside the chamber, and the sample injection passage is closed by the sphere except when the sample is injected. It is possible to prevent the vaporized septum component from entering the sample vaporization chamber by closing the sample injection passage with a sphere except when the sample is injected. Moreover, as described above, the carrier gas is unidirectionally flown to the gas contact surface of the septum by utilizing the septum purge flow path,
Since the carrier gas after cleaning is unilaterally discharged, the carrier gas containing the vaporized septum component does not enter the sample vaporization chamber even when the sphere is moved to open the sample injection passage.

In the above, when the sample injection passage is opened at the time of injecting the sample, it is preferable to move the sphere with the tip of the sample injection needle having the septum penetrated. After the sample injection, the sample injection needle is instantly withdrawn from the sample vaporization chamber, the sphere returns to its original position by gravity, and the sample injection passage is closed again. The time from penetration of this sample injection needle to removal is 1
Since the flow rate of the carrier gas during that time is about 1/60 milliliters / min during that time, it is considered that there is almost no carrier gas that can move through the sample injection passage.

In the above case, when the sample injection passage is closed except when the sample is injected, the center of the sphere is located at a position displaced from the approach path of the sample injection needle by a distance of 1/3 or less of the diameter of the sphere. By doing so, the tip of the needle does not hit the center of the sphere when the sample injection needle enters, and therefore, when the sphere is moved and the sample injection passage is opened when the sample is injected,
The sphere can be smoothly moved by the tip of the sample injection needle.

[0016]

EXAMPLE A septum purge type sample inlet for gas chromatograph according to a first example of the present invention will be described with reference to FIGS.

FIG. 1 is a sectional view showing the structure of a septum purge type sample inlet for a gas chromatograph according to this embodiment. The sample injection port of FIG. 1 includes an injection port body 1, an injection port head 2, an injection port cap 3, a head nut 4, a rubber retainer 5, an injection port septum 6, an insert packing retainer 7, a carrier gas inlet pipe 8, and a septum purge. Pipe 9,
It has a split-out pipe 10, a graphite packing 11, and a sample vaporization chamber 12. A column connection port 13 is provided in the lower portion of the sample vaporization chamber 12, and a glass insert split hole portion 14 and a glass insert 15 are provided on the outer periphery of the sample vaporization chamber 12.

In addition, the sample vaporization chamber 1 is provided in the injection port head 2.
2 is provided with a sample injection passage 16, and an upper portion of the sample injection passage 16 is a septum gas contacting chamber 17 facing the inlet septum 6 in which a sphere 18 can move and the sphere 18 injects the sample. The entrance to the passage 16 is closed or opened. A carrier gas passage 19 for supplying a carrier gas to the sample vaporization chamber 12 is provided above the sample vaporization chamber 12, and septum purge passages 20 and 21 are provided independently of the carrier gas passage 19.

When assembling the sample inlet,
First, the inlet body 1, the inlet head 2, the inlet cap 3, the head nut 4, the carrier gas inlet pipe 8,
The septum purge pipe 9, the split-out pipe 10 and the like constitute the main body of the sample injection port. Then, the inlet septum 6 is attached to the inlet head 2. Meanwhile, the graphite packing 11 is pushed into the insert packing retainer 7, and the glass insert 15 is pushed into the graphite packing 11. Then, the glass insert 15 is pushed into the inlet body 1.
Further, the head nut 4 is fastened to the injection port body 1 to complete the main body of the sample injection port. In the sample injection port of this embodiment, a sphere 18 movable in the septum gas contact chamber 17 is provided, and special septum purge flow paths 20 and 21 independent of the carrier gas passage 19 are provided. It is a feature.

Next, the flow of the carrier gas will be described with reference to FIG. 2, which is an enlarged view of the upper portion of the inlet with the septum purge. The carrier gas 30 supplied from the carrier gas inlet pipe 8 is divided into a carrier gas passage 19 communicating with the sample vaporization chamber 12 and a septum purge flow path 20. In FIG. 2, the carrier gas on the side of the carrier gas passage 19 is indicated by an arrow 31, and the carrier gas on the side of the septum purge flow path 20 is indicated by an arrow 32.

Carrier gas 3 which has entered the sample vaporization chamber 12
In order to transfer the vaporized sample from the column connection port 13 at the bottom of the sample vaporization chamber 12 toward the analytical column (not shown), 1 flows out in the direction indicated by the arrow 33 in FIG. It splits from the lower part of the sample vaporization chamber 12, flows through the glass insert split hole portion 14, and is discharged from the split out pipe 10 (shown by an arrow 34 in the figure). The ratio of the flow rate on the column side for analysis and the flow rate on the split out pipe 10 side (split ratio) is usually 1: 100.

On the other hand, the carrier gas 32 having entered the septum purge channel 20 reaches the upper part of the septum gas contact chamber 17 and constantly contacts the inlet septum 6 to flow in one direction while cleaning the surface of the inlet septum. The cleaned carrier gas containing the vaporized silicon rubber component passes through the septum purge passage 21 and is supplied from the septum purge pipe 9 to the arrow 35 in the figure.
It is discharged unilaterally as shown in. Further, except when the sample is injected, the sphere 18 closes the inlet of the sample injection passage 16 by gravity, and the septum gas contact chamber 17 side, that is, the septum purge flow channel 20 side and the sample vaporization chamber 12 side are partitioned,
Each is an independent channel. As described above, the cleaned carrier gas containing the vaporized silicon rubber component does not enter the sample vaporization chamber 12 and hence the analytical column.

When the sample is injected into the sample vaporization chamber 12,
A sample injection needle is inserted into the injection port septum 6 in the direction of arrow 40 in the figure, and the sphere 18 is moved in the septum gas contact chamber 17 by the sample injection needle to open the sample injection passage 16 to open the sample injection needle. The tip is made to reach the inside of the sample vaporization chamber 12 and the sample is injected. After the sample injection, the sample injection needle is instantly withdrawn from the sample vaporization chamber 12, the sphere 18 returns to its original position, and the sample injection passage 16 is closed again. The time from the penetration of this sample injection needle to the removal is within 1 second, and the flow rate of the carrier gas during that time is 1/60 ml /
Since it is about min, it is considered that there is almost no carrier gas that can move through the sample injection passage 16. Moreover, as described above, since the carrier gas is unidirectionally discharged to the gas contact surface of the inlet septum 6 by utilizing the septum purge flow path 20, the carrier gas after cleaning is unilaterally discharged. Even when the sample injection passage 16 is opened, the carrier gas containing the vaporized silicon rubber component does not enter the sample vaporization chamber 12.

FIG. 3 is a sectional view showing a general structure of a conventional septum purge type sample inlet for gas chromatograph, and FIG. 4 is an enlarged view of the upper portion of FIG. However, FIG.
In addition, in FIG. 4, the same members as those in FIGS. 1 and 2 are denoted by the same reference numerals. In the conventional septum purge type sample inlet port shown in FIG. 3 and FIG.
The septum gas contact chamber 17, the sphere 18, and the septum purge flow paths 20 and 21 are not provided. At this sample injection port, the carrier gas 30 supplied from the carrier gas inlet pipe 8 is not only supplied to the sample vaporization chamber 12 (see arrow 50 in the figure), but also flows into the sample injection passage 16a (in the figure). Cleaning is performed by touching the inlet septum 6 (see arrow 51), and the carrier gas after that is discharged from the septum purge pipe 9.

However, the sample injection passage 16a is shaped like a blind path by the inlet septum 6, and the pressure in the vicinity of the gas contact surface of the inlet septum 6 is almost constant, and gas movement is almost eliminated. Therefore, a part of the carrier gas flowing into the sample injection passage 16a directly flows out to the sample vaporization chamber 12 communicating with the sample injection passage 16a, and the silicon rubber component vaporized from the inlet septum 6 is also vaporized into the sample. Enter chamber 12, and thus the analytical column,
As a result, a ghost peak will appear.

On the other hand, in this embodiment, the septum purge flow passages 20 and 2 provided with the spherical body 18 movable in the septum gas contact chamber 17 and independent from the carrier gas passage 19.
By providing 1 specially, the carrier gas after cleaning containing the vaporized silicon rubber component does not enter the sample vaporization chamber 12 and hence the analytical column, and as a result, no ghost peak appears. The reliability of analysis can be improved.

FIG. 5 is a diagram comparing the analysis results by the sample injection port of this embodiment and the analysis results by the conventional sample injection port, and FIG. 5A is a chromatogram by the sample injection port of this example. , (B) are chromatograms by the conventional sample injection port. However, FIG. 5 shows the result of analyzing only the solvent for dissolving the sample. In the chromatogram of FIG. 5 (a), only the solvent peak appears, and the ghost peak hardly appears. On the other hand, in the chromatogram of FIG. 5B, in addition to the peak of the solvent, a ghost peak due to the silicone rubber component of the inlet septum 6 appears. As described above, in the analysis using the conventional sample injection port, a ghost peak due to the silicon rubber component appears even though the sample to be analyzed is not mixed. In the analysis using the section,
The ghost peak can be reduced to 1/10 or less of that in the conventional case, the quantitative accuracy of the gas chromatograph can be significantly improved, and highly reliable analysis can be performed.

According to the present embodiment as described above, the sphere 18 movable in the septum gas contact chamber 17 is provided, and the sphere 18 closes or opens the inlet of the sample injection passage 16 and the carrier gas passage 19 is provided. Since the septum purge flow paths 20 and 21 independent of each other are provided and the carrier gas for cleaning the inlet septum 6 is caused to flow in one direction, the carrier gas after cleaning containing the vaporized silicon rubber component is used for the sample vaporization chamber 12 and therefore for analysis. Will not enter the column. Therefore, the ghost peak does not appear, and the reliability of analysis can be improved.

Next, the septum purge type sample inlet for gas chromatograph according to the second embodiment of the present invention will be described with reference to FIG.

The sample injection port of this embodiment has the same basic structure as the embodiments of FIGS. 1 and 2, but the structure of the injection head 102 is slightly different. That is, the inlet head 10
2, the sample injection passage 116 is provided so that its center line is located at a position deviated from the entrance path 40 of the sample injection needle by the distance d. The distance d between the center line of the sample injection passage 116 and the entrance path 40 of the sample injection needle is the sphere 18
The diameter is set to 1/3 or less. Then, when the sample is injected into the sample vaporization chamber 12, the sphere 18 is moved by the sample injection needle penetrating the injection port septum 6 and the sample injection passage 116 is opened, but at that time, the sample injection needle bends a little and the sample injection is performed. It enters the passage 116, reaches the inside of the sample vaporization chamber 12, and injects the sample.

The above deviation distance d is a distance experimentally confirmed by the present inventor as a distance with which the sphere 18 can be smoothly moved by the tip of the sample injection needle. By displacing the approach path 40 of the injection needle in this way, the tip of the sample injection needle does not hit the center of the sphere 18 when the sample injection needle enters, and the sphere 18 is moved smoothly by the needle tip of the sample injection needle. The injection passage 116 can be opened.

As described above, according to this embodiment, not only the same effect as that of the first embodiment can be obtained, but also the sphere 18 can be smoothly moved by the needle tip of the sample injection needle at the time of sample injection. It is possible to improve workability.

In each of the above two embodiments, the sphere 18 is used, but even if there is no such sphere, the ghost peak is 1/5 of that of the conventional sample injection port.
It can be suppressed below.

Further, in the above two embodiments, a vacuum pump or the like is connected to the outlet of the septum purge pipe 9 to forcibly suck the carrier gas after cleaning containing the vaporized silicon rubber component from the septum purge pipe 9. Good.

[0035]

According to the present invention, since the septum purge flow path independent of the passage is provided to the sample vaporization chamber and the carrier gas is discharged in one direction with respect to the gas contact surface of the diaphragm, the vaporized diaphragm component is discharged. The carrier gas after cleaning containing is not introduced into the sample vaporization chamber, and no ghost peak appears, so that highly reliable analysis can be performed.

Since the sample injection passage is closed by the sphere except when the sample is injected, it is possible to prevent the vaporized diaphragm component from entering the sample vaporization chamber. Moreover, when the sample injection needle is used to move the sphere and open the sample injection passage, the carrier gas flows in one direction with respect to the gas contact surface of the diaphragm and is discharged. Never enter the vaporization room.

Further, since the center of the sphere is located at a position displaced from the entry path of the sample injection needle by a distance of ⅓ or less of the diameter of the sphere, the sphere is smoothly moved by the needle tip of the sample injection needle during sample injection. Can be moved to, and workability can be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the configuration of a septum purge type gas chromatograph sample inlet according to a first embodiment of the present invention.

FIG. 2 is an enlarged top view of a septum purge type sample inlet port for a gas chromatograph shown in FIG.

FIG. 3 is a cross-sectional view showing a general configuration of a conventional septum purge type gas chromatograph sample inlet.

4 is an enlarged top view of the septum purge type gas chromatograph sample inlet port shown in FIG. 3. FIG.

5 is a result of analysis by the sample injection port of FIG. 1 and FIG.
It is a diagram comparing the analysis results by the sample injection port of,
(A) is a chromatogram by the sample injection port of FIG.
(B) is a chromatogram by the sample injection port part of FIG.

FIG. 6 is a cross-sectional view showing the configuration of a septum purge type gas chromatograph sample inlet according to a second embodiment of the present invention.

[Explanation of symbols]

 1 inlet body 2 inlet head 3 inlet cap 6 inlet septum 8 carrier gas inlet pipe 9 septum purge pipe 10 split out pipe 12 sample vaporization chamber 13 column connection port 14 glass insert split hole 15 glass insert 16 sample injection passage 17 Septum Gas Contact Room 18 Sphere 19 Carrier Gas Passage 20, 21 Septum Purge Passage 102 Inlet Head 116 Sample Injection Passage

Claims (3)

[Claims] 1. A sample vaporization chamber which heats and vaporizes a sample to send it to a column, and a diaphragm which is provided at an inlet of a sample injection passage communicating with the sample vaporization chamber and through which a sample injection needle can penetrate when the sample is injected. In a septum purge type gas chromatograph sample inlet for cleaning the gas contact surface of the diaphragm with a carrier gas and discharging the gas out of the apparatus, the septum purge type gas chromatograph sample inlet is provided independently of the carrier gas passage to the sample vaporization chamber, A septum purge type sample inlet for gas chromatograph, which has a septum purge flow path for flowing a carrier gas for cleaning in one direction with respect to the gas contact surface of the diaphragm. 2. The septum purge type sample inlet for gas chromatograph according to claim 1, wherein a chamber provided between the sample vaporization chamber and the diaphragm of the sample injection passage, and at the time of injecting the sample. And a sphere capable of moving inside the chamber so that the sample injection passage is opened when the sample injection passage is closed. 3. The septum purge type gas chromatograph sample inlet part according to claim 2, wherein the sphere is
The sample injection needle is installed so that the center is located at a position displaced by 1/3 or less of the diameter of the sphere from the entry path of the sample injection needle except when the sample is injected, and when the sample is injected. A septum purge type sample injection port for a gas chromatograph, wherein the sample injection port is movable so as to open the sample injection passage.