JPH0772131A - Backflash method for concentration pipe - Google Patents

Abstract

PURPOSE:To remove effect of an interference component by making a carrier gas flow through a dead volume part between a passage switching device and a concentration pipe to discharge a sample in the dead volume prior to backflushing. CONSTITUTION:A sample cylinder 2 is operated to suck in the stale where ports a-j of a one-way valve 1 are connected. A fixed amount of atmospheric air S enters a concentration pipe 14 via a sample introduction port 13, a filter 12, the ports (b) and (c) and a pipe 15 and further, a pipe 4 via a pipe 16 and the ports (j) and (a). Here, benzene, toluene and xylene in the atmospheric air S are adsorbed by the concentration pipe 14. Then, a three-way solenoid valve 35 is operated and a normally closed port 35c is opened. Furthermore, with a three-way solenoid valve 35 and the sample cylinder 2 kept in operation, a carrier gas flows through pipes 28 and 36, the three-way solenoid valve 35, the ports (b) and (c), the pipe 15, the concentration pipe 14, the pipe 16, the ports (j) and (a) and the pipe 4 in that order to discharge the atmospheric air S in the dead volume parts 15 and 16 and the concentration pipe 14 from the normally closed port of the three-way solenoid valve 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a concentration tube provided in an atmospheric component concentration measuring apparatus using a gas chromatograph capable of measuring specific components such as benzene, toluene and xylene contained in the atmosphere. Regarding the backflush method.

[0002]

2. Description of the Related Art FIG. 4 is a diagram showing a general structure of an atmospheric component concentration measuring apparatus using the above-mentioned gas chromatograph (hereinafter, simply referred to as an atmospheric component concentration measuring apparatus). In FIG. The flow path switching device is composed of a well-known ten-way valve having, for example, 10 ports (indicated by 10 symbols a to j provided in the clockwise direction in the drawing). Reference numeral 2 is a sample cylinder, one end of which is connected to the port a through a pipe 4 having a three-way solenoid valve 3 and the other end of which is provided with a filter 6 through a three-way solenoid valve 5. It is connected to the mouth 7. In addition, 8 is a five-way solenoid valve, 9 is a ten-way valve diaphragm, and 10 is a capillary.

A port b adjacent to the port a is connected to an inlet 13 for the sample S via a tube 11 and a filter 12. Reference numeral 14 is a concentrating pipe connected between a port c adjacent to the port b and a port j adjacent to the port a via pipes 15 and 16. Although not shown in detail, the concentrating tube 14 is configured to generate heat when energized by itself and to raise the temperature. In addition, an appropriate concentration filler is provided inside thereof. Note that the concentration tube 14 may not be provided with a concentration filler.

Reference numerals 17 and 18 denote a separation column and an analysis column, respectively. The separation column 17 is provided with pipes 19 and 20 between a port d adjacent to the port c and a port h adjacent to one port j. Connected, analytical column 18
Has one end connected to a port g adjacent to the port h via a tube 21, and the other end connected to an analysis unit 22 including, for example, a photoionization detector. The other end of the analysis unit 22 is connected to the outlet 23.

The port e adjacent to the port d is connected to the back flush port 25 via the needle valve 24. A port f adjacent to the port e is connected to an inlet 30 for a carrier gas (for example, N ₂ gas) having a filter 29 via a pipe 28 having a needle valve 26 and a pressure regulator 27. The port i adjacent to the port h is connected to the portion of the pipe 28 between the needle valve 26 and the pressure regulator 27 via the pipe 31. In addition, 32 is a pump provided in a pipe 33 branched from the pipe 11 and connected to an air cooling device (not shown) provided in the vicinity of the concentration pipe 14, and 34 is a constant temperature bath.

When quantitatively analyzing benzene, toluene, and xylene in the atmosphere using the atmospheric component concentration measuring apparatus having the above-described structure, the following operation is performed.

The sample cylinder 2 is suctioned while the ports a to j of the ten-way valve 1 are connected as shown by the solid lines in the figure. As a result, a certain amount of sample (atmosphere) S is transferred to the sample inlet 13 and the filter 1.
2, the ports b and c, and the pipe 15 to enter the concentrating pipe 14, and the pipe 16 and the ports j and a to enter the pipe 4. At this time, benzene, toluene, and xylene in the sample S are adsorbed in the concentration tube 14.

The ten-way valve 1 is switched to the state shown by the dotted line in the figure, and the carrier gas is introduced from the inlet 30 and, at the same time, the concentrating tube 14 is heated to a predetermined temperature. By this heating, benzene, toluene, and xylene adsorbed in the concentrating tube 14 are desorbed to obtain a concentrated sample. Then, the carrier gas introduced from the inlet 30 enters the concentrating pipe 14 through the ports i, j and the pipe 16,
Further, it enters the separation column 17 through the pipe 15, the ports c and d, and the pipe 19. By the flow of the carrier gas, benzene, toluene, and xylene in the sample S are almost separated from the components after xylene.

The benzene, toluene, and xylene separated from the other components further leave the separation column 17, and the pipe 2
At the time of passing 0, ports h, g, the ten-way valve 1 is switched to the solid line state in the figure. As a result, the benzene, toluene, and xylene exiting the port g will be removed by the needle valve 2
The carrier gas having passed through the ports 6, f and g passes through the pipe 21 and is further sent to the analysis column 18. At the same time, the sample S containing the components after xylene remaining in the separation column 17 is supplied to the tubes 19, ports d, e by the carrier gas flowing into the separation column 17 through the ports i, h and the tube 20. And backflush via needle valve 24.

Benzene sent to the analytical column 18,
Toluene and xylene are further introduced into the analysis unit 22,
The desired chromatogram is obtained. Benzene after analysis,
Toluene and xylene are discharged from the discharge port 23.

[0011]

As can be understood from the above description, in the prior art, backflushing of the concentrating tube 14 was carried out at the same time when the temperature of the concentrating tube 14 was started to rise. was there. That is, at the start of the backflush, the sample S is also present in the dead volume portion around the concentrating tube 14, more specifically in the tubes 15 and 16 connecting the concentrating tube 14 and the ten-way valve 1. The sample S interferes with the concentrated sample, and as shown in FIG. 3 (B), other peaks of benzene, toluene, and xylene (represented by B, T, and X), which are the measurement target components, are included in the chromatogram. The oxygen peak O contained in the sample S and the dead volume part 1
The peaks A of the gas in 5 and 16 appeared, and these became interference components, and good separation was not performed, resulting in an error in the measurement results.

The present invention has been made in view of the above matters, and an object thereof is to provide a method for backflushing a concentrating tube capable of removing the influence of interference components and obtaining a good separation state. To provide.

[0013]

In order to achieve the above object, a method of backflushing a concentrating tube according to the present invention comprises a carrier in a dead volume portion between a flow path switching device and a concentrating tube before backflushing. By flowing the gas, the sample in the dead volume part is exhausted.

[0014]

According to the backflushing method of the concentrating tube,
Prior to backflushing the concentrating tube, the sample inside the dead volume part around the concentrating tube is exhausted, so even if the measurement target component is desorbed by raising the temperature of the concentrating tube, the sample inside the dead volume part Will not be interfered by. In particular, when the atmosphere is analyzed as a sample, the influence of oxygen contained in the atmosphere can be eliminated.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of the structure for carrying out the method for backflushing a concentrating tube according to the present invention. In the atmospheric component concentration measuring apparatus shown in this figure, port b of the Jikata valve 1 is used. 1 for connecting the sample inlet 13 with the sample inlet 13
1, the three-way solenoid valve 35 is installed so that the common port 35a is located on the port b side and the normally open port 35b is located at the sample introduction port 13, and the normally closed port port 35c is installed through the pipe 36. It is connected to the pipe 31.

In the atmospheric component concentration measuring apparatus constructed as shown in FIG. 1, the samples in the dead volume parts 15 and 16 between the ten-way valve 1 and the concentrating tube 14 are sampled before backflushing. To evacuate, the following operation should be performed.

That is, following the above steps, the three-way solenoid valve 35 is operated to open the normally closed port 35c. Further, in a state where the three-way solenoid valve 3 and the sample cylinder 2 are operated, the carrier gas is pipe 28-pipe 36-three-way solenoid valve 35-port b-port c-pipe 15-concentration pipe 1.
4-pipe 16-port j-port a-pipe 4 in that order,
Inside the dead volume parts 15 and 16 and the concentrating tube 14.
Purge the inside. As a result, the dead volume unit 1
The sample S in 5, 16 and the concentrating tube 14 is discharged to the outside of the apparatus through the normally closed port of the three-way solenoid valve 3. Needless to say, benzene, toluene, and xylene, which are the components to be measured, are not removed by the purging because they are adsorbed in the concentrating tube 14.

After the purge is performed, the subsequent operations are performed. FIG. 3 (A) is a chromatogram obtained in this way, and from this figure, the peak of oxygen and the gas in the dead volume parts 15 and 16 generated in the backflushing method of the conventional concentrating tube are shown. It can be seen that the peak A disappears and good separation is performed.

FIG. 2 shows another structural example for carrying out the method for backflushing the concentrating tube according to the present invention. In the atmospheric component concentration measuring apparatus shown in this figure, the port of the ten-way valve 1 is used. a pipe 19 for connecting d and the separation column 17
The three-way solenoid valve 37 is installed so that the common port 37a is located on the port d side and the normally open port 37b is located at the separation column 17, and the normally closed port port 3
7c is connected to the outlet 23 via a pipe 38.

In the atmospheric component concentration measuring apparatus constructed as shown in FIG. 2, before backflushing, the samples in the dead volume parts 15 and 16 between the ten-way valve 1 and the concentrating tube 14 are sampled. To evacuate, the following operation should be performed.

That is, following the above steps, the ten-way valve 1 is switched to the state shown by the dotted line in the figure, and the three-way solenoid valve 37 is operated to open the normally closed port 37c. Carrier gas is pipe 28-pipe 31-port i-
The flow proceeds in the order of port j-pipe 16-concentration pipe 14-pipe 15-port c-port d-pipe 19 to purge the dead volume parts 15 and 16 and the concentration pipe 14. As a result, the dead volume parts 15 and 16 and the concentration tube 1
Sample S in 4 is a normally closed port 37 of the three-way solenoid valve 37.
It is excluded to the outside of the device via c and the tube 38.

[0023]

As described above, in the present invention, the temperature of the concentrating tube is raised because the sample in the dead volume portion around the concentrating tube is exhausted prior to backflushing the concentrating tube. Thus, even if the component to be measured is desorbed, the sample in the dead volume portion is not interfered with, and a good separation state can be obtained. The present invention can eliminate the influence of oxygen contained in the atmosphere, particularly when the atmosphere is analyzed as a sample.

[Brief description of drawings]

FIG. 1 is a diagram showing the configuration of an apparatus for carrying out the method of the present invention.

FIG. 2 is a diagram showing another configuration of an apparatus for carrying out the method of the present invention.

FIG. 3A is a diagram showing a chromatogram obtained by the method of the present invention, and FIG. 3B is a diagram showing a chromatogram obtained by a conventional method.

FIG. 4 is a diagram showing a configuration of an apparatus for performing a conventional method.

[Explanation of symbols]

1 ... Flow path switching device, 14 ... Concentrating tube, 15, 16 ... Dead volume.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shuichi Ishimoto 2 Higashimachi, Kichijoin Miya, Minami-ku, Kyoto-shi, Kyoto

Claims (1)

[Claims] 1. A concentrating tube connected to a flow channel switching device and configured to perform backflushing by the flow channel switching operation of the flow channel switching device, wherein the flow channel switching device and concentration are performed before backflushing. A method for backflushing a concentrating tube, characterized in that a carrier gas is flowed to a dead volume portion between the tube and the tube to exhaust the sample in the dead volume portion.