JPH0783893A - Back flushing method for concentrating tube - Google Patents

Abstract

PURPOSE:To concurrently introduce a measurement object component adsorbed on a concentrating tube, toward a separation column for increasing the separability thereof, and improve concentration efficiency and measurement sensitivity by performing the back flushing of the concentrating tube in sufficiently heated state. CONSTITUTION:The temperature of a concentrating tube 14 is raised and when the temperature reaches the prescribed level, a ten-way valve 1 is operated for selection from a solid line position to a dotted line position. Carrier gas is thereby introduced through an introduction port 30 to back flush the tube 14 all at once. As a result, concentration efficiency in the tube 14 increases, and a measurement object component adsorbed on the tube 14 is introduced toward a separation column 17 almost concurrently. Separability and measurement sensitivity can, therefore, be improved.

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. 3 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.

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.

At the same time as switching the ten-way valve 1 to the state shown by the dotted line in the figure, 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 and j and the pipe 16, and further the pipe 15, the ports c and d, and the pipe 19
And enters the separation column 17. 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, the backflush of the concentrating pipe 14 was performed at the same time as the temperature rising of the concentrating pipe 14 was started, so that the concentrating pipe 14 was heated. In the process of being backflushed, the backflush is gradually performed. When the temperature of the concentrating tube 14 is raised, the measurement component gases adsorbed by the concentrating tube 14 are generally in the order of decreasing boiling point.
And is led to the separation column 17 side, but as shown by the symbol A in FIG. 4, the peak width of the measurement component gas is widened, and the dead volume portion around the concentrating tube 14 is
More specifically, the peak B of the sample S existing in the tubes 15 and 16 connecting the concentrating tube 14 and the ten-way valve 1 appears separately from the peak A. As a result, conventionally, the peak B interferes with the separation of the peak A, and the concentration efficiency in the concentrating tube 14 is reduced, which inevitably reduces the sensitivity.

The present invention has been made in view of the above matters, and an object of the present invention is to provide a method for backflushing a concentrating tube, which improves the separability and enhances the concentrating efficiency in the concentrating tube, and enables measurement with high sensitivity. To provide.

[0013]

In order to achieve the above object, the method for backflushing a concentrating tube according to the present invention performs backflushing while the temperature of the concentrating tube is sufficiently raised.

[0014]

According to the backflushing method of the concentrating tube,
Since the concentrating tube is backflushed after the concentrating tube is sufficiently heated, the components to be measured adsorbed in the concentrating tube can be discharged toward the separation column almost at the same time.

[0015]

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

The apparatus for carrying out the method for backflushing the concentrating tube according to the present invention is completely the same as that shown in FIG. 3, and some of the operation steps described above are changed. That is, in the above description, the ten-way valve 1 was switched to the state shown by the dotted line in the drawing so that the carrier gas was introduced from the inlet 30 and at the same time the concentrating tube 14 was heated to a predetermined temperature. Then, instead of this, after the temperature of the concentrating tube 14 is sufficiently raised, 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 to make the concentrating tube 14 Backflush.

That is, as shown in FIG. 1, when the temperature of the concentrating tube 14 reaches a certain temperature, the ten-way valve 1 is turned on, and the state shown by the solid line in FIG. 3 is shown by the dotted line. Introducing the carrier gas into the inlet 3 with the state switched.
It is introduced from 0 to backflush the concentrating tube 14.

FIG. 2 shows the change over time in the amount of gas when the concentrating tube 14 is backflushed as described above. The peak A of the measurement component gas is different from the peak in FIG. The width is getting narrower and higher. This is because backflushing was performed after almost all the components to be measured adsorbed in the concentrating tube 14 were desorbed. Therefore, by introducing such a measurement component gas into the analysis section 22 via the separation column 17 and the analysis column 18, it is possible to improve the separability and perform highly sensitive measurement.

[0019]

As described above, in the present invention, the backflush is performed while the temperature of the concentrating tube is sufficiently raised, so that the concentration efficiency in the concentrating tube can be enhanced. Therefore, the components to be measured adsorbed in the concentrating tube can be led out toward the separation column almost at the same time, so that the separability is improved and the measurement can be performed with high sensitivity.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the method of the present invention, showing the relationship between the temperature of a concentrating tube and the operating time of a ten-way valve.

FIG. 2 is a diagram showing a temporal change in the amount of gas output from the concentrating pipe when the method of the present invention is carried out.

FIG. 3 is a diagram showing an example of an apparatus to which the method of the present invention is applied.

FIG. 4 is a diagram showing a temporal change in the amount of gas output from a concentrating tube when a conventional method is carried out.

[Explanation of symbols]

 1 ... Flow path switching device, 14 ... Concentrating tube.

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

Claims (2)

[Claims] 1. A concentrating tube connected to a channel switching device and configured to perform backflushing by the channel switching operation of the channel switching device, wherein the backflushing is performed with the concentration tube being sufficiently heated. The method of backflushing a concentrating tube, characterized in that 2. The method for backflushing a concentrating tube according to claim 1, wherein the concentrating tube is provided with an appropriate concentrating filler.