JP2828239B2 - Gas sample introduction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for introducing a gas sample in a gas chromatograph, and more particularly, to an apparatus for introducing a gas sample for suppressing fluctuations in the baseline of a gas chromatogram with a simple apparatus configuration.

[0002]

BACKGROUND ART When analyzing the composition of various gas samples (hereinafter sometimes referred to as "sample gas") by gas chromatography, for example, CO and C, which are trace components in hydrogen gas, are analyzed.
When analyzing O _2, generally it is performed as follows. First, C in the sample gas was determined by gas chromatography.
The peak areas of CO and CO ₂ for a standard gas (concentration is known) close to the O and CO ₂ concentrations are obtained, and a calibration curve of the area and the concentration is created. Next, using the same gas chromatograph, the peak areas of CO and CO ₂ in the sample gas are determined, and the CO and CO ₂ concentrations are determined from the above calibration curve.

When a standard gas used for obtaining such a calibration curve is introduced into a gas chromatograph, and when a sample gas used for actual analysis of a sample is introduced into a gas chromatograph, it is generally switched to a measuring tube. An introduction means consisting of a cock is used. That is, first, a desired amount of a sample gas or a standard gas is sampled into the measuring tube via the cock. Next, by switching the cock, the sample gas or the standard gas in the measuring tube is introduced into the separation column of the gas chromatograph.

[0004] This introduction operation will be described in more detail with reference to FIG. FIG. 2 shows a state when an actual sample gas is analyzed, but the same applies when an analysis is performed on a standard gas.

In FIG. 2, reference numeral 100 denotes a gas chromatograph main body. At the time of sample collection (measurement), the hexagonal cock 3b of the sample introduction part 3 composed of the measuring tube 3a and the switching hexagonal cock 3b is indicated by a black line. It is switched so that such a flow path is formed. At this time, a carrier gas is sent from the carrier gas cylinder 1 via the pressure regulator 2 and the pressure gauge via the line 11 to charge the line and the peripheral devices, and flows through the opening → the opening flow path of the cock 3b. It flows from the separation column 5 to the reactor 6 to the detector 7. If the pressure of the carrier gas is ^{1.7kgf / cm 2 (0.7kgf / cm} 2 in gauge pressure, hereinafter the same), the system (i.e., the line for analysis), the particular separation column 5, 1. A pressure of 7 kgf / cm ² will be applied.

On the other hand, the sample gas is introduced from the line 12 and flows through the flow path from the opening of the cock 3b to the opening.
A predetermined amount is measured (collected) by the measuring pipe 3a, and the remainder flows out into the atmosphere through a flow path of → opening → opening. At this time, a water bottle was placed at the outlet, and the outflow of the sample gas was confirmed with underwater bubbles. When the generation of the bubbles stopped (atmospheric pressure), the cock 3b was switched, and a white line was drawn. The flow path is as shown.

[0007] This flow path serves as a flow path for introducing the sample into the gas chromatograph. That is, the sample is carried by the carrier gas from the cylinder 1, flows through the flow path from the opening of the cock 3 b → the opening → the measuring pipe 3 a → the opening → the opening, and is introduced into the separation column 5.

By the way, before the sample is introduced into the separation column 5, as described above, 1.
Although a pressure of 7 kg / cm ² is applied, the introduction of an atmospheric pressure sample causes a pressure drop. Due to this pressure drop, the flow rate of the carrier gas after the pressure regulator 2 fluctuates. This change in the flow rate of the carrier gas causes, for example, a change in the baseline (α in FIG. 4) of the gas chromatogram shown in FIG. It takes a long time of about 3 to 6 minutes to eliminate the fluctuation of the baseline and stabilize the baseline (in the example of FIG. 4, it takes about 5 to 6 minutes).

If a peak appears before the baseline is stabilized, the peak area is integrated in the changing baseline, and the peak area cannot be accurately measured (integration processing). Explaining with an example schematically shown in FIG. 5, the peak area of the i component is originally only the portion a, but if the base line exists in the portion shown by the dotted line, the portion shown by the b (Ie, the baseline indicated by the dotted line does not appear in the actual chromatogram, so the peak area of the i component is a + b
Is integrated as the area of the image).

As described above, if there is a change in the baseline, the peak area cannot be accurately integrated, and the analysis accuracy of the gas chromatograph decreases. Especially,
If such a variation occurs when a calibration curve is obtained using a standard gas, the reliability of the calibration curve itself is reduced, and its significance as a calibration curve is lost.

In order to eliminate the fluctuation of the baseline,
A method of setting the pressure of the carrier gas at the time of sample measurement to the atmospheric pressure and a method of setting the pressure of the sample gas to the pressure of the carrier gas can be considered. However, if the former method is adopted,
The air may leak into the gas chromatograph, and accurate analysis cannot be performed. The latter method requires a large amount of sample gas and cannot be applied to a gas chromatograph on the premise that a small amount of sample gas is introduced.

[0012]

An object of the present invention is to provide an apparatus for introducing a gas sample in a gas chromatograph used for analysis of various gas samples in addition to the above-mentioned hydrogen gas under the above-mentioned circumstances. An object of the present invention is to provide an apparatus that does not cause line fluctuations without requiring a significant change in the apparatus configuration of a conventional gas chromatograph.

[0013]

Means for Achieving the Object To achieve this object, a gas sample introduction device according to the present invention comprises a gas chromatograph having a main body line from a carrier gas cylinder to a detector through a sample introduction section and a separation column. A sample measuring tube and a gas sample introducing / discharging tube in which a first hexagonal cock and a second hexagonal cock are arranged in series in a main body line of a sample introduction part, and a flow path is connected to the first hexagonal cock on the downstream side. A pipe is arranged, a pressure compensating measuring pipe and a flow rate control valve having a flow path connected to the second hexagonal cock on the upstream side are arranged, and a pressure compensating line from the carrier gas cylinder to the second hexagonal cock is provided. At the time of measurement, a carrier gas cylinder → a line for pressurization → a second 6-way cock → a pressurization measuring tube → a second 6-way cock → a flow control valve → a line outside the system and a sample introduction tube → a first 6-way Forming a line to cock → sample metering pipe → first hexagonal cock → sample discharge pipe → outside of the system,
At the time of analysis, carrier gas cylinder → line for main body → second
6-way cock → pressure-compensation measuring pipe → 2nd 6-way cock → 1st 6-way cock → sample measuring pipe → 1st 6-way cock → separation column → detector line And

[0014]

In the gas sample introduction device of the present invention, the first hexagonal cock performs the same operation as the switching cock in the gas sample introduction means in the conventional gas chromatograph described above, and is provided upstream of the first hexagonal cock. The second hexagonal cock placed and its peripherals (ie,
The supplementary pressure measuring pipe, the flow control valve, and the supplementary pressure line from the carrier gas cylinder) serve to suppress the fluctuation of the baseline when introducing the gas sample.

[0015] The variation of the baseline, as described above,
When a sample gas at an atmospheric pressure is introduced into a separation column under a pressure higher than the atmospheric pressure, a pressure drop occurs in the separation column, and this phenomenon is caused by the pressure drop. Therefore, if the pressure drop of the separation column at the time of sample introduction is suppressed, the fluctuation of the baseline is eliminated. In the apparatus of the present invention, the pressure drop of the separation column at the time of sample introduction is suppressed by the second hexagon cock and its peripheral devices.

That is, first, at the time of measuring the sample gas (including the standard gas, the same applies hereinafter), the carrier gas is sent from the carrier gas cylinder through the pressure compensating line to reach the second hexagonal cock, and the By the switching, the pressure is measured and sampled through the flow path formed in the cock into the supplementary pressure measuring pipe. Then, the remaining carrier gas that has not been collected in the supplementary pressure measuring pipe passes through the flow path in the second hexagonal cock again and is discharged out of the system via the flow rate control valve.

On the other hand, the sample gas flows from the sample introduction tube to the first
The six-way cock is weighed and sampled through the flow path formed in the cock by switching the cock. Then, the remaining sample gas not collected in the sample measuring tube passes through the flow path in the first hexagonal cock again and is discharged out of the system from the sample discharging tube.

Further, at the time of this sample measurement, a main body line from the carrier gas cylinder to the detector via the second hexagonal cock, the first hexagonal cock and the separation column is also provided.
The carrier gas for charging is introduced, and the pressure of the line for the main body, and thus the pressure of the separation column, is changed to the pressure of the carrier gas (1.7 kgf /
cm ² and thus held in) "0.7 kgf / ^cm 2 in gauge pressure".

In this way, when the sample gas measuring operation is completed, the first and second hexagonal cocks are switched, and
Move on to sample gas analysis. At the time of this analysis, the pressure line is not used, but the main line is used exclusively.

That is, the carrier gas is sent from the carrier gas cylinder through the main body line to the second hexagonal cock, and the sample is weighed through the flow path formed in the cock by switching the cock. It enters the pressure-supplying measuring tube from the opposite direction to the time (that is, the side that was the outlet of the carrier gas at the time of sample measurement). Then, at the time of the above-mentioned sample measurement, the carrier gas for replenishment, which has been measured (collected) in the measuring tube, accompanies the flow through the flow path in the second hexagonal cock again to reach the first hexagonal cock.

The first hexagonal cock also passes through a flow path formed in the cock by switching the cock, and also in the opposite direction to the above-described sample measurement (ie, the sample gas outlet at the sample measurement). ) Enters the sample measuring tube. Then, at the time of the above-described sample measurement, the sample gas for analysis (sampled) weighed (collected) in the measuring tube is accompanied, and again passes through the flow path in the first hexagonal cock and reaches the separation column.

As described above, in the apparatus of the present invention, the sample gas introduced into the separation column is entrained by the carrier gas sent from the carrier gas cylinder at the time of analysis and the carrier gas for pressure compensation in the pressure gauge. The Rukoto. That is, the pressure of the sample gas introduced into the separation column is adjusted by the pressure of the carrier gas for supplementary pressure, thereby suppressing the pressure drop of the separation column from occurring during the transition to the analysis operation.

Further, by switching the first and second six-way cocks, when the operation is shifted from the weighing operation to the analysis operation, the flow control valve having a flow path connected to the second six-way cock is connected to
If the carrier gas for supplementary pressure in the supplementary pressure measuring pipe is flowed little by little, the pressure can be adjusted, and the pressure fluctuation at the time of switching the cock can be suppressed as much as possible.

In the gas sample introduction device of the present invention having the above-described operation, when the size of the sample measuring tube is changed, in other words, when the amount of the sample to be analyzed is changed, the pressure compensating measurement is performed. It is not always necessary to change the size of the tube, but it can be dealt with by adjusting the pressure of the carrier gas for pressure compensation. However, when the size of the sample measuring tube is largely changed, it may be necessary to change the size of the supplementary pressure measuring tube.

[0025]

FIG. 1 shows an embodiment of a gas sample introducing apparatus according to the present invention. 1, the same reference numerals as those in FIG. 2 indicate the same functional units as those in FIG. In FIG. 1, a first hexagonal cock 3b and a second hexagonal cock 3b are provided in a sample introduction section 3 of a main body line 11 from a carrier gas cylinder 1 of a gas chromatograph main body 100 to a detector 7 through a sample introduction section 3 and a separation column 5. And the six-way cock 4b are arranged in series.

A sample measuring tube 3a and sample introduction / discharge tubes 12a and 12b are arranged in a first hexagonal cock 3b located downstream of the main body line 11 with their respective flow paths connected to each other. The compensating pressure measuring pipe 4a and the flow control valve 4c are connected to the second hexagonal cock 4b
Are arranged by connecting the respective flow paths. Then, separately from the main body line 11, a pressure compensating line 10 from the carrier gas cylinder 1 to the second hexagonal cock 4b is provided.

In such a configuration, by switching between the first hexagonal cock 3b and the second hexagonal cock 4b, a flow path indicated by a black line is formed in both cocks 3b, 4b during sample measurement. . That is, one is a carrier gas cylinder 1 → pressure regulator 2 → compression line 10 → second hexagonal cock 4b (opening → opening) → compression pressure measuring pipe 4a → second hexagonal cock 4b (opening → opening) Part)
→ Flow control valve 4c → Line outside the system. In this line, a carrier gas for pressure suppression for suppressing the pressure drop of the separation column 5 at the time of the transition to the analysis operation is supplied to the pressure-measuring tube 4a.
This is a line for weighing (collecting).

The other is a sample introduction tube 12a → first hexagonal cock 3b (opening → opening) → sample measuring tube 3
a → the first hexagonal cock 3b (opening → opening) → sample discharge tube 12b → line to the outside of the system. This line is a line for measuring (collecting) a sample to be analyzed in the sample measuring tube 3a.

At the time of sample measurement, together with these two lines, the carrier gas cylinder 1 → second hexagonal cock 4b (opening → opening) → first hexagonal cock 3b
A line of (opening part → opening part) → separation column → reactor 6 → detector 7 is also formed. This line is composed of a main body line 11 and various kinds of equipment (e.g., a flow path in the first and second hexagonal cocks 3b and 4b during an analysis operation, a separation column 5, a reactor 6, a detector 6). 7) is a line for charging with carrier gas.

At the time of analysis, the first hexagonal cock 3b
And by switching the second hexagonal cock 4b, in FIG.
Flow paths indicated by white lines in both cocks 3b and 4b, that is, carrier gas cylinder 1 → pressure regulator 2 → body line 11 → second hexagonal cock 4b (opening → opening)
→ Compensating pressure measuring pipe 4a → second hexagonal cock 4b (opening →
(Opening) → first hexagonal cock 3b (opening → opening) → sample measuring tube 3a → first hexagonal cock 3b (opening → opening) → separation column 5 → reactor 6 → detector 7 line Is formed.

The first hexagonal cock 3b and the second hexagonal cock 4b may have the same configuration, the same capacity, and the same material, or may use different hexagonal cocks. . In this example, the first hexagonal cock 3b
Is used for the conventional gas chromatograph, and the second hexagonal cock 4b is a commercially available product.

The supplemental pressure measuring tube 4a is connected to the sample measuring tube 3a.
The same material and the same material as those described above may be used, or different materials may be used. The capacity of the supplementary pressure measuring tube 4a is selected from a capacity of about 0.1 to 10 mL depending on the operating conditions, and is used.
Plays an important role in the device of the present invention,
It must be strictly selected based on the calculation formula described later.

The pressure-supply line 10 can be made of any material and size.
They may be of the same size or different. In this example, a stainless steel pipe with an outer diameter of 2
mm and an inner diameter of 1.5 mm are used.

The pressure regulator 2 provided on the pressure-supply line 10
Has a pressure adjustment range of 0 to 10 kgf / cm ² (gauge pressure), and a pressure gauge has a pressure scale range of 0 to 10 kg.
Those having a flow rate of about f / cm ² (gauge pressure) are used, and the flow control valve 4c having a flow rate of about 1 to 10 mL / min is used.

The first six-way cock 3b and the second
The switching with the six-way cock 4b may be performed separately by manually operating each of the four-way cocks 4b. For example, a "simple universal joint device" proposed by the inventor of the present invention (Japanese Utility Model Application No. 4-59974). ) May be performed simultaneously. In the example of FIG. 1, the first hexagonal cock 3b and the second
And the universal joint device 21 via an interlocking line 20.
Is activated to switch at once.

In the above-described configuration, first, in order to perform the measurement (collection) operation of the sample, the first and second hexagonal cocks 3b and 4b are switched at once by the universal joint device 21, and the above-described sample is operated. Three lines (a line around the first hexagonal cock 3b, a line around the second hexagonal cock 4b, a line for the main body and a line for charging peripheral devices with a carrier gas) are formed at the time of weighing.

In the line around the first hexagonal cock 3b of these three lines, the sample gas to be analyzed passes from the introduction tube 12a through the flow path (→) in the first hexagonal cock 3b. It is introduced into the measuring tube 3a and a predetermined amount is measured (collected). The remaining sample gas again passes through the flow path (→) in the first hexagonal cock 3b, and the discharge pipe 1
2b is discharged out of the system.

Simultaneously with the measurement (sampling) of the sample gas, in the line around the second hexagonal cock 4b, the carrier gas for pressure compensation passes from the carrier gas cylinder 1 through the line 10 for pressure compensation, and is supplied to the pressure regulator 2 and the pressure gauge. While the pressure is being adjusted, the pressure is sent to the second hexagonal cock 4b, passes through the flow path (→) in the cock 4b, is introduced into the supplementary pressure measuring pipe 4a, and a predetermined amount is measured (collected). The remaining carrier gas passes through the flow path (→) in the second hexagonal cock 4b again, reaches the flow control valve 4c, and is discharged out of the system.

In the charging line, the carrier gas is sent from the carrier gas cylinder 1 through the main body line 11 while the pressure is adjusted by the pressure regulator 2 and the pressure gauge. Channel (→)
And the flow path (→) in the first hexagonal cock 3b,
After passing through the separation column 5, the reactor 6, and the detector 7, it is discharged out of the system.

When the sample weighing operation is completed in this way, the first and second hexagonal cocks 3b and 4b are switched again by the universal joint device 21 to form the above-mentioned line for analysis. When the line is formed, that is, when the operation is shifted from the sample measuring operation to the analyzing operation, the carrier gas for the supplementary pressure in the supplementary pressure measuring tube 4a is supplied to the flow control valve 4
The pressure fluctuation in the system is suppressed by flowing a small amount from c outside the system.

In the analysis line, the carrier gas is sent from the carrier gas cylinder 1 to the main body line 11 while the pressure is adjusted by the pressure regulator 2 and the pressure gauge. The flow path in the cock 4b (
→) to the compensating pressure measuring pipe 4a, and along with the compensating carrier gas in the measuring pipe 4a, again through the flow path (→) in the second 6-way cock 4b, and the first 6-way cock 3
b.

In the first hexagonal cock 3b, the cock 3b
Through the internal flow path (→) to the sample measuring tube 3a,
The sample gas in the measuring tube 3a is sent again to the separation column 5 through the flow path (→) in the first hexagonal cock 3b with the sample gas in the measurement tube 3a. The analysis of the sample gas is performed.

Since CO and CO ₂ separated by the separation column 5 cannot be detected by the flame ionization detector, they react with the hydrogen of the carrier gas in the reactor 6 to form methane (CH ₄ ). 7

In such an analysis operation, in addition to the sample gas entrained by the carrier gas from the carrier gas cylinder 1, the separation column 5 also includes a supplementary pressure measuring tube 4 a at the time of sample measurement.
The carrier gas that has been weighed (collected) is introduced. The carrier gas in the supplementary pressure measuring tube 4a acts as a supplementary pressure, and the pressure applied to the separation column 5 by the carrier gas introduced for charging during sample measurement does not drop.

As described above, in the apparatus of the present invention, the pressure and the amount of the carrier gas measured (collected) in the supplementary pressure measuring pipe 4a depend on the achievement of the object of the present invention (the separation column 5 at the transition to the analysis operation). This is an important factor in preventing pressure drop. The pressure of the carrier gas is adjusted by the pressure regulator 2 disposed in the pressure-supply line 10, and the amount of the carrier gas is controlled by the capacity of the pressure-supply measuring pipe 4a.

Hereinafter, a method of obtaining the capacity of the supplementary pressure measuring pipe 4a will be described. First, the capacity of the supplementary pressure measuring pipe 4b is obtained by Expression (1) of Equation 1.

[0047]

(Equation 1)

[0048]

(Equation 2)

Next, a specific method of obtaining the capacity of the supplementary pressure measuring pipe 4a will be described. The preconditions at this time are as shown in Table 1.

[0050]

[Table 1]

Under the preconditions in Table 1, the sample measuring tube 3a
10 mL of a sample gas at atmospheric pressure is introduced into the measuring tube 3.
The pressure in a is changed to the inlet pressure of the separation column 5 (1.7 kg of pressure sent for charging at the time of sample measurement).
The pressure is increased to 1.7 kgf / cm ² with a carrier gas of f / cm ^2.
A carrier gas at a pressure of gf / cm ² requires 4.1 mL.

This 4.1 mL carrier gas is supplied by the carrier gas in the pressure compensating measuring tube 4a. This 4.
1 mL is the pressure of the supplementary pressure measuring tube 4a of 6.2 kgf / cm ²
In this case, it is sufficient that 1.1 mL of carrier gas for pressure compensation is measured in the pressure compensation measuring pipe 4a.

However, in order to prevent the pressure drop in the separation column 5, it is necessary to keep the inside of the supplementary pressure measuring tube 4 a at the same pressure as the inlet pressure of the separation column 5 (ie, self-holding). The self-holding amount of the supplementary pressure measuring pipe 4a is 6.2 k
If the pressure is gf / cm ² and the volume is xmL, the supplementary pressure measuring tube 4a
The amount of gas in the inside, and consequently the capacity of the supplementary pressure measuring pipe 4a, is 6.2.
At a pressure of kgf / cm ² , 1.1 + x (mL) is sufficient.

From the above, Expression (4) of Expression 3 is established.

[0055]

(Equation 3)

When formula (4) is rearranged, formula (5) of formula 4 is obtained.
When this equation (5) is expressed by parameters, it becomes the following equation (1).

[0057]

(Equation 4)

When rearranging the expression (5), x = 0.42. Therefore, the capacity of the supplementary pressure measuring pipe 4a is 6.2 kg.
When operating at a pressure of f / cm ² , 1.1+
0.42 = 1.5 mL is sufficient.

In this way, the capacity of the supplementary pressure measuring pipe 4a can be obtained. This relationship is shown in Table 2, and the calculated value and the actual value are almost the same.

[0060]

[Table 2]

Specific Example By using a gas chromatograph employing the gas sample introduction device of the present invention shown in FIG. 1 and a conventional gas chromatograph shown in FIG.
(A conditioning gas containing O: 10.2 ppm and CO ₂ : 10.0 ppm) was analyzed four times. The results were as shown in Table 4. In Table 4,
The results obtained by gas chromatography employing the apparatus of the present invention shown in FIG. 1 are shown as examples, and the results obtained by conventional gas chromatography shown in FIG. 2 are shown as comparative examples.

[0062]

[Table 3]

FIG. 3 shows a chromatogram by gas chromatography employing the apparatus of the present invention shown in FIG. FIG.
Chromatogram by conventional gas chromatograph of
This was shown in FIG. As is clear from FIG. 3, when the apparatus of the present invention is employed, the baseline does not fluctuate, and therefore, accurate integration of the peak area can be performed.

[0064]

[Table 4]

Table 4 shows No. The same testing machine was used for all
This is the result of using the same sample and the same area processing parameters. The standard deviation and the coefficient of variation are almost the same in the example and the comparative example, but the CO component is about 35% larger in the comparative example than in the example. The CO ₂ component is about 18% higher in the comparative example than in the example. Further, as described above, in FIG. 3, since the baseline is stable and the peak of the CO component is clearly seen, the value of the embodiment can be regarded as the true value of the CO component. Example value is C
Assuming the true value of the O component, the comparative example is about 35%
It can be seen that the values in the examples accurately integrate only the peak area of the CO component.

[0066]

As described above in detail, according to the gas sample introduction device of the present invention, a six-way cock, a pressure regulator, a flow control valve, these components and a gas chromatograph can be used without requiring a significant change in the conventional gas chromatograph. By using only a simple member such as a main body or a pipe connecting to a carrier gas cylinder or the like, it is possible to suppress the fluctuation of the baseline at the time of analysis. As a result, it is possible to provide a gas chromatograph which can perform analysis with high accuracy at extremely low cost.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing one embodiment of a gas chromatograph employing a gas sample introduction device of the present invention.

FIG. 2 is a schematic explanatory view showing a conventional gas chromatograph.

FIG. 3 is a chromatogram when hydrogen gas is analyzed by a gas chromatograph employing the apparatus of the present invention shown in FIG.

4 is a chromatogram obtained by analyzing hydrogen gas by the conventional gas chromatograph shown in FIG.

FIG. 5 is a diagram schematically showing a state of an integration process using the chromatogram shown in FIG. 4;

[Explanation of symbols]

REFERENCE SIGNS LIST 100 Gas chromatograph main body 1 Carrier gas cylinder 2 Pressure regulator 3 Sample introduction unit 3b First hexagonal cock 3a Sample measuring tube 4b Second hexagonal cock 4a Pressure compensating measuring tube 4c Flow control valve 5 Separation column 6 Reactor 7 Detector 10 Complement Line for pressure 11 Line for main body 12a Line for sample introduction 12b Line for sample discharge 20 Line for interlocking the first 6-way cock and the second 6-way cock 21 Simplified universal joint device proposed earlier

Claims (1)

(57) [Claims] 1. A gas chromatograph having a main body line from a carrier gas cylinder to a detector via a sample introduction part and a separation column, wherein a first six-way cock and a second six-way cock are provided in a main body line of a sample introduction part. A sample weighing tube and a sample introduction / discharge tube with a flow path connected to a first hexagonal cock on the downstream side are arranged in series, and a supplementary tube with a flow path connected to a second hexagonal cock on the upstream side. A pressure measuring pipe and a flow control valve are arranged, and a pressure compensating line from the carrier gas cylinder to the second hexagonal cock is provided. At the time of sample measurement, the carrier gas cylinder → the pressure compensating line →
2nd 6-way cock-> supplementary pressure measuring pipe-> 2nd 6-way cock-> flow control valve-> line outside system and sample introduction pipe-> 1st 6-way cock-> sample measuring pipe-> 1st 6-way cock-> sample discharge A pipe is formed from the pipe to the outside of the system. At the time of analysis, a carrier gas cylinder is used.
6-way cock → pressure-compensation measuring pipe → 2nd 6-way cock → 1st 6-way cock → sample measuring pipe → 1st 6-way cock → separation column → detector line Gas sample introduction device.