JPH1123554A - Gas chromatograph device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformly heat a capillary tube connecting a column to a detector. SOLUTION: A capillary tube 21 is arranged in a hollow tube 24, and make-up gas heated by a heating part 27 is supplied into the hollow tube 24. The make-up gas flows in a nozzle 33, and it is mixed with sample gas fed through the capillary tube 21 so as to be jetted in an ionization chamber 31. Gas heated at fixed temperature continuously flows through the hollow tube 24, and hence the capillary tube 21 can be extremely uniformly heated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a gas chromatograph, and more particularly, to an interface for connecting a gas chromatograph column and a detector (including a mass spectrometer).

[0002]

2. Description of the Related Art When a column of a gas chromatograph is connected to a detector, an appropriate interface is often used between the two because of the structure of the detector. FIG. 3 is a configuration diagram of a main part showing an example of a gas chromatograph device using a surface ionization type ionization detector as a detector. In a gas chromatograph (GC) unit 10, a predetermined amount of carrier gas is supplied via a sample vaporization chamber 11 to a column 13 heated to an appropriate temperature by a column oven 12. The liquid sample injected into the sample vaporization chamber 11 is vaporized and carried into the column 13 on a carrier gas flow. Each component in the sample is temporally separated while passing through the column 13, and after leaving the column 13, is introduced into the detection unit 30 through the capillary tube 21 of the interface unit 20.

In the detection unit 30, a nozzle 33 is provided protruding from an ionization chamber 31 in a vacuum atmosphere, and a sample gas transported by a capillary tube 21 and a makeup gas supplied through an auxiliary gas tube 32 are provided. Is nozzle 3
3 mixed inside. The tip of the nozzle 33 is a heater 33a
The nozzle 33 is heated to an appropriate temperature. Since the gas is continuously supplied to the nozzle 33, the pressure difference between the inside and the outside (in the ionization chamber 31) increases, and the gas gushes from the ejection hole of the nozzle 33 vigorously. In front of the nozzle 33, a heated solid surface 34 is arranged.
The sample molecules ejected from and accelerated to the supersonic region come into contact with the solid surface 34 and are ionized by the surface ionization. The generated ions reach the detector 35 and are detected as an ion current corresponding to the number of generated ions. In addition,
A configuration of a mass analyzer that separates the generated ions for each mass number and detects the ions may be employed.

As a make-up gas, a gas having a low specific gravity, such as He, is usually used. By mixing the sample gas and the make-up gas, even a sample molecule having a relatively large specific gravity and being hardly accelerated can be accelerated to a supersonic region by repeating two-body collision with the molecules of the make-up gas.

In the above configuration, the temperature of the column 13 is set within a range of about 100 to 450 ° C. according to the kind of the target component and the like (mainly according to the boiling point of the target component).
When the temperature of the sample gas reaching the end of the column 13 decreases,
Since the gas flow is deteriorated and the analysis accuracy is deteriorated, a heat equalizing block 22 made of metal such as aluminum is provided in close contact with the periphery of the capillary tube 21, and the heat equalizing block is heated by the heater 23. Like that. At this time, the temperature of the capillary tube 21 is set to a temperature substantially equal to or slightly higher than that of the column 13.

[0006]

However, even if a heat equalizing block 22 having a high thermal conductivity is used, the temperature of the heat equalizing block 22 is slightly different between a portion close to the heater 23 and a portion far from the heater 23. It is difficult to heat completely uniformly in the longitudinal direction. If the heating of the capillary tube 21 has uneven temperature, the sample components may aggregate at a low temperature portion, and the peak of the chromatogram may be widened or lost.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a gas chromatograph apparatus capable of improving the temperature non-uniformity of a capillary tube at an interface. Is to do.

[0008]

SUMMARY OF THE INVENTION The present invention, which has been made to solve the above problems, is directed to a gas chromatograph having an interface for introducing a sample separated by a column of a gas chromatograph into a detector. The interface section comprises: a) a sample conduit connected to the column outlet; b) a hollow tube containing the sample conduit; c) gas supply means for flowing gas through the hollow tube; d. Heating means for heating the gas before the gas is introduced into the hollow tube.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a gas chromatograph apparatus according to the present invention, a gas is heated to a predetermined temperature outside a hollow tube by a heating means and then supplied into the hollow tube, and a sample conduit is circulated around the hollow tube. Heated by gas. Since the gas at a predetermined temperature is continuously supplied around the sample conduit, its heat capacity is very large, and the wall surface of the sample conduit is heated almost uniformly.

In the gas chromatograph apparatus according to the present invention, when a makeup gas (auxiliary gas) is used in the detector, the gas supplied to the hollow tube can be used as the makeup gas. In this case, the makeup gas used to heat the sample conduit was:
It is mixed with the sample gas transported by the sample conduit in or near the detector.

[0011]

According to the gas chromatograph of the present invention, since the sample conduit is heated with high uniformity, each component contained in the sample gas eluted from the column is introduced into the detector without delay. For this reason, it is possible to prevent the peak of the chromatogram from spreading or disappearing due to the non-uniform temperature.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the gas chromatograph according to the present invention will be described below. FIG. 1 is a configuration diagram of a main part of the gas chromatograph device of the present embodiment. In the gas chromatograph device of the present embodiment, the above-described ionization detector is used for the detection unit 30. In the interface section 20 in the present embodiment, the capillary tube 21 connected to the column 13 is disposed inside a substantially coaxial stainless steel (or other material) hollow cylindrical tube 24. A heat insulating material 25 is provided around the hollow tube 24 in close contact with the hollow tube 24 to prevent dissipation of heat from the hollow tube 24.

A heating gas supply pipe 26 is connected to the hollow tube 24 on the GC section 10 side, while a gas supply port 33 b communicating with the nozzle 33 is opened on the detection section 30 side. A make-up gas (for example, He gas) at a predetermined flow rate is introduced into the heating gas supply pipe 26, and after being heated to a predetermined temperature by a heating unit 27 provided in the middle thereof, is supplied to the hollow pipe 24. The heating unit 27 includes, for example, a soaking block provided in close contact with the outer periphery of the heating gas supply pipe 26 and a heater for heating the soaking block. The heating temperature is appropriately set in the range of about 100 to 500 ° C. depending on the column oven temperature.

When the makeup gas heated by the heating unit 27 flows into the hollow tube 24, it flows so as to surround the capillary tube 21, and heats the outer peripheral wall of the capillary tube 21. Then, the gas flows into the nozzle 33 through the gas supply port 33b and is mixed with the sample gas carried through the capillary tube 21. This mixed gas is heated by the heater 33a to a temperature of several hundred degrees C. to a temperature close to 1,000 degrees C.
It is released as a supersonic free jet from the gas outlet at the tip. The makeup gas supplied to the hollow tube 24 is deprived of heat by the capillary tube 21 and the surrounding heat insulating material 25. However, since the makeup gas heated to a predetermined temperature is continuously supplied, a very large heat capacity is obtained. Having. For this reason, the temperature in the hollow tube 24 is maintained almost uniformly at a predetermined temperature.

The detecting section 30 can be configured as shown in FIG. 1 other than the ionization detector as long as it requires a makeup gas.

In the ionization detector used in the above embodiment, the makeup gas is usually further heated in the nozzle 33. However, when it is necessary to lower the temperature of the makeup gas and mix it with the sample gas, Can be configured as shown in FIG. That is, the gas supply pipe 2 that supplies the cooled (that is, not heated) makeup gas to the nozzle 33 of the detection unit 30
8 is connected to mix the heated makeup gas that has passed through the hollow tube 24 with the unheated makeup gas so as to reduce the temperature thereof. Thereby, the temperature of the makeup gas in the nozzle 33 can be adjusted to an appropriate temperature lower than the heating temperature of the heating unit 27.

Further, in this configuration, when it is desired to rapidly lower the temperature of the capillary tube 21 after the end of analysis or the like, a large amount of cold gas is introduced into the hollow tube 24 through the gas supply tube 28, and this gas is discharged. The gas may be discharged to the outside through the heating gas supply pipe 26.

The gas introduced into the hollow tube 24 does not have to be a makeup gas, but a gas dedicated to heating the capillary tube 21 is used, and the gas is discharged outside without being introduced into the nozzle 33. Is also good. Further, the gas discharged through a septum purge channel or a split channel (not shown) connected to the sample vaporizing chamber 11 may be reused. When the detection unit 30 performs ionization using the chemical ionization method, the reaction gas used for the ionization can be reused.

Furthermore, the above embodiment is merely an example, and it is apparent that modifications and changes can be made as appropriate within the scope of the present invention.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a main part of an embodiment of a gas chromatograph device according to the present invention.

FIG. 2 is a configuration diagram of a main part of a gas chromatograph device according to another embodiment of the present invention.

FIG. 3 is a configuration diagram of a conventional gas chromatograph device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Gas chromatograph (GC) part 12 ... Column oven 13 ... Column 20 ... Interface part 21 ... Capillary tube 24 ... Hollow tube 25 ... Heat insulation material 26 ... Heated gas supply tube 27 ... Heating part 30 ... Detection part 31 ... Ionization Chamber 33 ... Nozzle 33b ... Gas supply port 34 ... Solid surface 35 ... Detector

Claims (1)

[Claims] 1. A gas chromatograph apparatus having an interface for introducing a sample separated by a column of a gas chromatograph into a detector, the interface comprising: a) a sample conduit connected to a column outlet; b) a hollow tube containing the sample conduit; c) gas supply means for flowing a gas through the hollow tube; d) heating to heat the gas before the gas is introduced into the hollow tube. Means, and a gas chromatograph apparatus comprising: