JPS6071950A - Gas chromatograph - Google Patents

Abstract

PURPOSE:To improve the measuring accuracy of a sample gas and to enable analysis of a trace component with high accuracy by drawing the sample gas into a measuring tube having large capacity and enriching the gas. CONSTITUTION:The 1st cock 2 is operated to connect a measuring tube 1 to a sample bag 3 and a pump 4 and at the same time the 3rd cock 8 is operated to close both ends of an enriching tube 13. A refrigerator 14 is then operated to cool the gas down to -40-50 deg.C. The pump 4 is operated upon ending of the above-described preparation to draw a specified amt. of a sample gas into the tube 1. The 1st-3rd cocks 2, 6, 8 are thereafter operated to form the flow passage consisting of a carrier gas source 5, the tube 1, the tube 13 and a resistance tube 7 so that the sample gas in the tube 1 is fed forcibly by the carrier gas to one port of the tube 13. The volatile component in the sample gas is thus captured by thoroughly cooled porous polymer beads 12. the diluting gas and carrier gas are released through the tube 7 into the atm. and only the intended component is enriched.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Application of the Technology The present invention relates to a gas chromatograph suitable for analyzing trace components contained in gas.

Conventional technology When analyzing trace components contained in a gas using a gas chromatograph, normally, as shown in Fig. 4,
Using a low-temperature concentration means formed by cooling a concentration tube A filled with a distribution agent to -183'C with a liquid oxygen jar B,
A fixed amount of gas from the sampler bag C is sampled through the concentrator tube A using an integrated flowmeter to condense trace components in the gas at a low temperature. Next, one end of the concentrator tube is connected to the sample inlet of the gas chromatograph and concentrated. The tube is heated to desorb concentrated components and then injected into a gas chromatograph column.

Although such a method can significantly improve the detection sensitivity of trace components, there is a problem in that errors tend to occur in the measurement of the sampling amount and the analysis accuracy decreases.

C. Objectives In view of the above-mentioned problems, an object of the present invention is to provide a gas chromatograph that can detect minute amounts of components with high precision and high sensitivity.

20. The structure of the present invention, that is, the feature of the present invention is that the sample gas from the Daikichi i5 metering tube is concentrated.

E. Embodiments The details of the present invention will be explained below based on illustrated embodiments.

FIG. 1 is a configuration diagram of an apparatus showing an embodiment of the present invention, and the reference numeral 1 in the figure indicates a capacity of 200 to 1000 m that can sample a sample gas in an amount in which trace components can be detected. The metering tube is configured so that it can be switched and connected to a sample bag 3, a pump 4, a carrier gas source 5, and a second multi-way cock, which will be described later, through a first multi-way cock 2, respectively. Reference numeral 6 denotes the aforementioned second multi-way cock, which is configured to be switchable and connectable to the first multi-way cock 2, the carrier gas source 5, the resistance tube 7, and the third multi-way cock 8, respectively. 9 is a concentration section, and a third multi-way cock 8
Thus, both ends are closed, and a flow path from the metering tube 1 to the resistance tube 7 and a flow path from the carrier gas source 5 to the column 11 of the gas chromatograph 10 are formed. This concentration section consists of porous polymer φ beads 12 with capture characteristics intermediate between distribution and adsorption, as shown in Figure 2.
The concentrating tube 13 filled with
5 and are encased together with a heat insulating material 16, and are configured to be cooled to -40 to 50'C during the concentration process and heated to +100 to 150'C during desorption.

In addition, the reference numeral 17 in the figure is a resistance tube having the same fluid resistance as the concentration tube 13, and is used to adjust the resistance of the carrier gas flow path system when introducing the sample gas from the metering tube 1 into the gas chromatograph 10. It is for.

In this embodiment, the first cock 2 is operated to connect the metering tube l to the sample bag 3 and the pump 4, and at the same time the third
Operate the cock 8 to close both ends of the concentrating tube 13, and operate the refrigerator 14 to cool it down to -40 to 50"C. After completing these preparations, operate the pump 4 to begin weighing. Sample a certain amount of sample gas in v1 (3rd
Figure ■).

When sampling is completed, operate the first, second, and third multi-way cocks 2.6.9 to form a flow path spanning the carrier gas source 5, metering tube 1, concentration tube 13, and resistance tube 7. , the sample gas contained in the metering tube I is forced into one port of the concentration tube I3 using a carrier gas, and the volatile components contained in the sample gas are captured in the sufficiently cooled porous polymer beads 12. Further, the diluent gas and carrier gas are discharged into the atmosphere through the resistance tube 7, and only the target component is concentrated (II). When the concentration of the sample gas in the metering tube 1 is completed in this way, the third multi-way cock 8
is closed, the heater 15 is energized to heat the concentration tube 13,
The target component captured by the porous polymer beads 12 is vaporized and brought into a state where it can be easily desorbed (III). In this state, the second multi-way cock is operated to form a flow path from the carrier gas source 5 via the third cock 8 to the chromatograph 10, and at the same time the third multi-way cock 8 is opened.
The carrier gas is caused to flow in the direction opposite to that of the concentration step, and the target component is injected into the column 11 by a backflush method. This allows all concentrated components to be injected into the column at the same time without any time delay, generating peaks that correspond to the separation ability of the column, and providing analytical results with high resolution and precision.

In this example, analysis of higher hydrocarbons such as methane CH4 or higher excluding ethane C2H6 was explained as an example, but in the case of ethane, the third cock was set to be a six-way cock, for example, and the analysis was performed in the same direction as the concentration step. By injecting the target component into the chromatograph by flowing a carrier gas through the chromatograph, analysis can be performed with higher sensitivity.

Effects As explained above, according to the present invention, the sample gas is sampled into a large-capacity measuring tube and concentrated, which improves the measurement accuracy of the sample gas and allows trace components to be detected with high precision. can be analyzed. Furthermore, since we use porous polymer beads in the concentrating section that capture volatile components through an intermediate action between distribution and adsorption, a normal refrigeration system can be used as a cooling means, eliminating the need for replenishment of liquid oxygen, etc. , maintenance can be simplified.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an apparatus showing one embodiment of the present invention, and FIG.
The figure is a sectional view showing an embodiment of the concentrating means in the above device, FIG. 3 is an explanatory diagram showing the operation of the above device, and FIG. 4 is a block diagram of an example of a conventional low-temperature concentrator. . 1...Measuring Af 2.6.8...Multi-way cock 5
... Carrier gas source 9 ... Low temperature concentration means 10
...Gas chromatograph applicant Shimadzu Corporation Representative Patent attorney Kei Nishikawa Katsuhiko Kimura

Claims (1)

[Claims] A large-capacity measuring tube capable of sampling a sample gas in an amount in which trace components can be detected, a low-temperature concentrating means filled with porous polymer pieces as a capture agent for volatile components, and a concentrating means from the measuring tube. A gas chromatograph comprising: a channel from the concentrating means to the column; and means for selectively switching a channel from the concentrating means to the column.