JPH09127074A - Adjusting device for flow rate of carrier gas at sample injection port for gas chromatograph - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adjusting device by which the consumption amount of a carrier gas is saved by providing, in order to control the flow rate of the carrier gas to be supplied to a sample injection port individually, two systems of adjusting parts of the carrier gas. SOLUTION: When a sample is injected in a split injection method, a stop valve 4 is set to an open state, and a three-port solenoid valve 7 is set to a state A. At this time, required carrier gases are supplied to a sample injection port 1 from normal mass-flow controllers 2, 3. At this time, the entrance pressure of a capillary column 9 is controlled by a back-pressure regulator 8, and a carrier gas in a small quantity is introduced into the column. In addition, the carrier gas is discharged through a septum purge flow-rate regulator 6 and the pressure regulator 8. Then, when a sample is injected in a splitless injection method, the valve 4 is set to a closed state, and the solenoid valve 7 is set to a state B. Then, in an analytical operation, the valve 4 is set to a closed state, the solenoid valve 7 is set to the state A, and a carrier gas in a small quantity is introduced into the injection port 1 by the controller 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sample inlet for a gas chromatograph, and more particularly to a carrier gas flow rate controller using a capillary column.

[0002]

2. Description of the Related Art In the conventional apparatus, most of the carrier gas is constantly exhausted from the split outlet, or an expensive electrically controlled flow control device is used. Therefore, there was a problem in terms of cost. A related device of this type is, for example, Japanese Patent Laid-Open No. 4-105062.

[0003]

The gas chromatograph is a device that can be said to be the king of analytical instruments used in more than 100,000 units worldwide, mainly in the petroleum and petrochemical fields.
Therefore, many companies use hundreds of units, and the consumption of carrier gas and the like reaches a huge amount.
Recently, a capillary gas chromatograph that uses a capillary column that uses He gas, which is only natural, as a carrier gas, has become the mainstream, and the running cost thereof is great. Further, since a large amount of natural He gas is used, there is a problem from the viewpoint of protecting the global environment. In this regard, the present invention provides a carrier gas flow controller for a gas chromatograph which reduces the use of carrier gas exhausted during analysis when using a capillary column and saves the consumption of carrier gas.

[0004]

When a capillary column is used in the analysis of a gas chromatograph, the carrier gas flow rate in the column is about several ml / min so as not to impair the separation efficiency of the column. The amount of sample to be analyzed is ideally used in an amount of about 1% of the packed column so as not to impair the separation efficiency of the capillary column. The volume is about 0.001-0.01 μl,
It is in the range that cannot be collected with existing injectors. Actually, about 0.1 to 1 μl is measured with a microsyringe, a sample divider is provided to divide into about 1%, and about 1% μl is collected. The remaining 99/100 is discharged to the atmosphere outside the gas chromatograph together with the carrier gas by flowing through a capillary column.

The present invention has been devised so that the carrier gas released into the atmosphere is not released. That is, about 100 ml / min necessary for division is supplied to the sample injection port only when the sample is injected, and about several ml / min is supplied to the sample injection port during analysis and standby. Further, since the time of staying in the sample injection port varies depending on the amount of sample, viscosity, etc., it is possible to control the switching timing of this flow path and save carrier gas consumption.

In order to achieve the above object, the present invention has two channels of carrier gas to be supplied to a sample injection port, one of which supplies about 100 ml / min of carrier gas for sample injection, and the other one. Is a few ml for analysis and standby
The carrier gas of min can be supplied. The flow rate in the column was controlled by a back pressure regulator to control the column inlet pressure, and the flow path could be switched by a three-port solenoid valve during the splitless injection method. As described above, the flow rate of the carrier gas in the column is always constant, and moreover, the carrier gas can be supplied to the sample injection port by the required minimum amount, so that the carrier gas can be saved.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will now be described with reference to FIG.
This will be described with reference to FIG.

FIG. 1 is a flow path diagram during analysis of a carrier gas flow rate controller for a sample inlet for a gas chromatograph according to the present invention in a split injection method and a splitless injection method. FIG. 2 is a flow path diagram at the time of sample injection in the splitless injection method.

The structure of the flow controller will be described below with reference to FIG.

A carrier gas adjusted by the mass flow controller 2 and the mass flow controller 3 is supplied to the sample inlet 1. A stop valve 4 is attached in front of or after the mass flow controller 2 (indicated in front of the mass flow controller 2 in FIG. 1, but either may be used). By opening and closing the stop valve 4, the mass flow controller 2 is installed. The carrier gas supplied from 2 is controllable. The stop valve 4 is controlled by the stop valve control unit 5. The supplied carrier gas is divided into one introduced into the capillary column 9 inside the sample inlet 1 and one discharged to the outside through the septum purge flow rate controller 6 and the back pressure regulator 8. The flow rate of the carrier gas introduced into the capillary column 9 is adjusted by controlling the column inlet pressure by the back pressure regulator 8.

The operation will be described below separately for sample injection, analysis, and standby.

First, at the time of sample injection in the split injection method, the stop valve 4 is open, and the three-port solenoid valve is shown in FIG.
State. At this time, the carrier gas of about 100 ml / min is normally supplied from the mass flow controller 2 to the sample inlet 1 from the mass flow controller 3 of several ml / min. At this time, the inlet pressure of the capillary column 9 is controlled by the back pressure regulator 8 and a carrier gas of several ml / min is introduced into the column. In addition, several ml / min through the septum purge flow controller 6 and 10 through the back pressure regulator 8.
About 0 ml / min of carrier gas is discharged. Therefore,
If the sample is injected in this state, about 1% of the total amount of the sample is introduced into the capillary column 9 and analyzed.

Next, when the sample is injected in the splitless injection method, the stop valve 4 is closed and the three-port solenoid valve 7 is in the state shown in FIG.

The stop valve 4 is closed during analysis and standby (both split injection method and splitless injection method).
The three-port solenoid valve 7 is in the state shown in FIG. At this time, several ml / min of carrier gas supplied from the mass flow controller 3 is introduced into the sample inlet 1. Since the inlet pressure of the capillary column 9 is controlled by the back pressure regulator 8, the same several ml / min of carrier gas as when the sample is injected is introduced. In this state, the carrier gas discharged from the back pressure regulator 8 is small, and the carrier gas is hardly wasted. Since the time for opening the stop valve 4 is about 1 minute, the amount of carrier gas consumed is about several ml / min. Therefore, about 1% of the carrier gas is consumed as compared with the conventional case.

According to this embodiment, the consumption of the carrier gas can be reduced to about 1%, so that the running cost can be reduced.

[0016]

According to the present invention, since the consumption amount of the carrier gas can be reduced to about 1% of the conventional value, the running cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a system diagram of a flow path during analysis of a carrier gas flow rate controller of a sample injection port for a gas chromatograph according to the present invention in a split injection method and a splitless injection method.

FIG. 2 is a systematic diagram of a flow path during sample injection in the splitless injection method.

[Explanation of symbols]

1 ... Sample inlet, 2, 3 ... Mass flow controller, 4
... Stop valve, 5 ... Stop valve control unit, 6 ... Septum purge flow rate controller, 7 ... Three-port solenoid valve, 8 ... Back pressure regulator, 9 ... Capillary column.

Claims (1)

[Claims] 1. A carrier gas flow controller that vaporizes a liquid sample and supplies the carrier gas to a sample inlet for a gas chromatograph, which is introduced into a column, in order to reduce the consumption of the carrier gas, usually during sample injection. In order to control the flow rate of the carrier gas to be supplied to the sample injection port individually during the analysis, a two-system carrier gas control unit is provided, and a 3-port solenoid valve is used to switch between split injection method and splitless injection method A carrier gas flow rate controller for a sample inlet for a gas chromatograph, which is characterized in that