JPS5995458A - Sampling method of gas chromatograph - Google Patents

Abstract

PURPOSE:To measure accurately a gaseous sample, to introduce it into a column at the same pressure as the equilibrium pressure and to eliminate an evil influence due to the variation of pressure by carrying out the equilibrium of pressure at sampling for measuring by a gaseous carrier at a substantially constant pressure. CONSTITUTION:A three-way solenoid valve 15 is inserted into the outlet of a pump 2, and a two-way solenoid valve 16 is connected to the inlet side of a flow meter 4 to move these valves mutually. In this gaseous sample flow passage 6, a buffer pipe 17 is inserted between the three-way solenoid valve and a sampling valve 13. The buffer pipe 17 is made of the same material as a measuring pipe 12 and has a volume about five times or more that of the said pipe 12. Thus, just before sampling, the gaseous carrier from a pressure gauge 9 is branched and passed to not only the three-way solenoid valve, but also a column 10. Consequently at the sampling time, only the gaseous sample at the same pressure is inserted into the column 10, and any variation of the pressure is not observed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas chromatograph sampling method, and more particularly to a gas chromatograph sampling method in which a metering tube is operated by a switching pulp.

A general sampling mechanism of a Gaff chromatograph is to introduce a sample gas into a measuring tube at normal atmospheric pressure, and introduce (sampling) the sample gas in the measuring tube into a column using a carrier gas. In this mechanism, for example, as shown in FIG.
A sample gaff flow path (6) leading from the connected pump +21 and electromagnetic pulp (3) to the atmosphere outlet (5) connected to the flow meter +41, and the carrier gas cylinder (7).
) directly connected to the pressure regulating valve (8) and pressure gauge (9) to the column (10I) and the carrier and analysis gas flow path ILI.
Place the six-way valve sampling pulp (131) for selectively inserting the metering tube L121 into the position shown by the solid line in the figure, open the tongmagi pulp (3), and open the pump (2).
) to drive.

As a result, the sample gaff and pull gaff are introduced into the sample gaff flow path including the metering tube (121) and the atmospheric outlet (5).
) is purged from the metering tube [12
It fills up within 1. The sample Ganu in the measuring tube 1121 is -
Pulp (rD to switch to the dashed line position in Figure 131'i)
, is forced into a carrier gas and introduced (sampled) into the column 1101, and the separated components are measured by a detector (141).

In this case, the amount of sample gas sampled in the metering tube 1121 with a constant volume is constant on the assumption that the atmospheric pressure is constant, but even with normal pressure fluctuations, if the pressure is low,
mb, or about 1040 mb in the case of high pressure, and this changes the absolute amount of sample introduced into the column by about ±3%, which is one error factor.

The gear gaff pressure during which the sample is introduced into the column is sufficiently higher than atmospheric pressure, so
Pressure fluctuations occur in the column during sampling, resulting in shock peaks of 4E, which tend to be confused with the peaks of early eluted components, and chromatographic base fluctuations.

SUMMARY OF THE INVENTION In order to eliminate the above-mentioned disadvantages in gas sampling in gas chromatographs, the present invention provides a method in which pressure equilibration during metered sampling is performed with a carrier gas at substantially constant pressure.

This makes it possible to accurately measure the sample gas (based on a constant pressure) and to introduce it into the column at the same pressure as its equilibrium pressure, thereby minimizing adverse effects caused by pressure fluctuations.

The following is a second example of an apparatus configuration for carrying out all the methods of the present invention.
This will be explained according to the diagram.

In the flow path shown in Fig. 2, there is a difference from the conventional example shown in Fig. 1.
While fully inserting the solenoid valve 1151, insert the flowmeter (4)
A two-way electromagnetic pulp 1t61f is connected to the inlet side of the sample gas θ, and a buffer pipe is connected between the three-way electromagnetic pulp + i5+ sampling pulp (131) in the path (6) to this sample gas θ. (This is because the ID has been inserted. The other components are the same as those of the conventional example shown in FIG.
It is desirable that the volume of the weighing tube 1121 made of the same glue as 5 times or more is loaded.

Next, a procedure for implementing the gas sampling method of the present invention using the configuration shown in FIG. 2 will be explained. First, sampling pulp u
l- Place it in the position shown by the solid line, and place the three-way electromagnetic pulp 1i51 f
The "a-b" circulation position is of course connected to the outlet of the pump (2) and the buffer pipe d71, and the opening/closing pulp LL61 *Opening such pulp 115)
, σ6) are desirably performed simultaneously by interlocking movements. As a result, the sample pulp flows into the buffer pipe (1'r), which is drawn out to the pump 121 and passes through the three-way electric cable U, and further flows into the sampling pulp U.
31'e and is put into the weighing tube 121. The opening/closing pulp u6) of the weighing tube outlet flow path is opened, and the sample gas is passed from this knob to the conductivity meter +41k and then to the atmosphere discharge port +5.
Purged from 1.

Next, the three-way pulp l151 'ag c-b' is set to the open position, and the opening/closing pulp (161'< closed) is operated in conjunction with this.

The carrier gas source (7) preferably has a gas pressure several times the atmospheric pressure, so that the carrier gas exiting from the three-way bulkhead (151) passes through the buffer pipe while fully compressing the sample gas contained under atmospheric pressure. 17) Flow into.

This allows the buffer via "(lη and metering tube L1
The sample gas in 21- is compressed in the downstream side of the former U force and in the range from the entire metering tube 1121 to the opening/closing valve ub+. However, it should be noted that if the sample gas is left in this state for a period of time, the sample gas and carrier gas will mix due to the gas diffusion phenomenon.

Therefore, the sample gas is compressed by the carrier gas at the same time that the pressure of the carrier gas, which was at atmospheric pressure and was connected to the buffer via 117) and the metering tube U21 and has temporarily dropped, returns to a constant initial control pressure (1,000 ryo). Switch to the sampling process by switching u9, [161 and u3.

At this point, the diffusion between the carrier gaff and the sample tube occurs only at the contact portion of the two tubes downstream of the buffer via, and the measuring tube 1121 is filled with only the sample.

Then, by placing the sampling valve U at the position indicated by the broken line in the figure, the metering tube 121 is inserted between the pressure gauge (9) and the column 1101 in the carrier and analysis gas flow (Lll), and the column (10j is 11 The sample gas sampled almost completely by constant pressure equilibrium by the carrier gun is sent in. Immediately before this sampling, the carrier gas from the pressure gauge (9) is branched to the three-way electromagnetic pulp ti51. Therefore, during sampling, the sample gas at the same pressure is inserted into the column [01], and no pressure fluctuation occurs. do not have.

The method of the present invention is as described above.
The effects can be summarized as follows.

(11 Effects of fluctuations in atmospheric pressure (Metric f(i) when sample gas is sampled at atmospheric pressure 1,000 yen.

(21) Not affected by pressure fluctuations during sampling (confusion of shock peak occurrence with component heat, base return movement, etc.).

(3) Sampling by carrier gas. f
To compress, the metering tube is inversely proportional to this pressure +! lllt
, it can be made smaller.

The smaller the chromatograph, the less the chromatographic link.

The present invention is as described above, and makes it possible to implement a useful sampling method of 1C, 4°, and just by making some changes to the conventional flow path configuration. For sample gas compression () <) V button u5) (Connected to D channel port C) As a power source, another gas source having the same pressure as the carrier cannula may be used.

[Brief explanation of the drawing]

FIG. 1 is a flow diagram showing a conventional Ganu chromatography sampling flow path, and FIG. 2 is a diagram showing an example of a C-arame line for carrying out the method of the present invention. +21 - - -Pump +41 - - -Flow rate meter +51----Atmospheric discharge port (62--Sample flow path (7) -Carrier gas cylinder +81- −
---One pressure valve +91 ---One pressure gauge [101-----One column ttU----Carrier and analysis power flow path U21
---Measuring tube [131------- Sampling tube] Detector

Claims (1)

[Scope of Claims] A metering tube is selectively inserted into either a sample gas flow path from a sample gas source to an atmospheric outlet, and a carrier and analysis gas flow path from a carrier gas source to a column inlet. of sampling pulp, and a buffer chamber 47' having a capacity sufficiently larger than that of the measuring tube is provided on the upstream side of the sampling pulp in the sample gas flow path.
At the same time, 30,000 pulp for selectively introducing the sample gas from the sample gas source and the carrier gas from the carrier gas source into the buffer pipe is inserted into the inlet side of the buffer pipe, and In a gas chromatograph system in which an opening/closing pulp is inserted in front of an atmospheric discharge port in a sample gas flow path, the measuring tube is inserted into the sample gas flow path via the sampling pulp, and the sample gas source marked @ is connected to the sample gas source. By connecting to the buffer pipe through a three-way pulp and opening the opening/closing pulp, a sample gas is introduced into the buffer pipe and the metering tube, and the carrier gas source is connected to the buffer pipe through the three-way pulp. By connecting to a buffer pipe and closing the opening/closing pulp, the sample gas in the buffer pipe and metering tube is compressed toward the metering tube side by carrier gas pressure, and the sampling pulp is in a second position, and the A gas chromatograph sampling method characterized by introducing a sample gas measured into a measuring tube into a column and analyzing it.