JPH08262003A - Insert for sample injction port of gas chromatograph - Google Patents

Abstract

PURPOSE: To prevent a sample from being stuck to the inner wall surface of a glass insert by a method wherein a heat-resistant resin layer is formed on the inner face of the glass insert. CONSTITUTION: A carrier gas which has been introduced from a carrier-gas introduction port 6 is moved in a gap between a glass insert 1 and a heat- resistant resin layer 2 and it is finally introduced into an analytical column 7. A sample is not thereby, stuck to the inner wall surface of the insert 1. The resin layer 2 is formed in such a way that, e.g. a heat-resistant tube manufactured by an extrusion molding operation is inserted into the inside of the insert 1. As a heat-resistant resin, polytetrafluoroethylene, a tetrafluoroethylene- hexafluoropropylene copolymer and a tetrafluoroethylene-fluoro(alkyl vinyl ether) copolymer can be enumerated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sample inlet insert for a gas chromatograph.

[0002]

2. Description of the Related Art As shown in JP-A-63-124959, a sample injection section of a conventional gas chromatograph is provided with a heat block section and a cylindrical insert made of glass inside thereof. In this method, the insert is heated by heating the heat block part, and the liquid sample injected into the insert is introduced into the analytical column by the vaporized carrier gas. However, when using a glass insert, when injecting a sample having a glass adsorbing property such as a nitro compound, the injected sample is adsorbed by the silanol group on the inner wall surface of the glass insert, and therefore reproducible and accurate. However, there is a drawback in that it is impossible to carry out a quantitative analysis.

In order to eliminate such problems, glass inserts are subjected to silane treatment using a silylating reagent such as dimethyldichlorosilane to cap silanol groups that react with silanol groups on the glass surface. Inactivated and used for analysis.
However, if the capping is not sufficient, or if the capping is peeled off due to repeated use of the sample or solvent for a long period of time, the silanol groups are exposed again on the inner surface of the glass insert, and the silanol groups become active, resulting in adsorption of the sample. There was a problem that occurred.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks, and an object of the present invention is to provide an inner wall surface of an insert when a sample having a glass adsorbing property is analyzed by a gas chromatograph. An object is to provide an insert for a sample inlet of a gas chromatograph in which a sample is not adsorbed.

[0005]

The insert for a sample inlet of a gas chromatograph of the present invention comprises a glass insert having an analytical column inserted at one end and a septum attached at the other end, and a heat block for heating the glass insert. A heat-resistant resin layer is formed on the inner surface of the glass insert at a sample inlet of a gas chromatograph having a portion and a carrier gas inlet opening to the glass insert.

The sample inlet insert of the above gas chromatograph is used in a normal gas chromatograph, and a longitudinal sectional view of an example thereof is shown in FIG. In the figure, reference numeral 1 is a glass insert, one end of which is connected to a column 7 in an airtight state, and the other end of which is attached to a septum 4. The septum 4 is fixed by a cap 5.

The glass insert 1 is provided with a carrier gas introduction port 6 opening on the side wall thereof, and the carrier gas (not shown) introduced from the carrier gas introduction port 6 is the glass insert 1 and the heat resistant resin. Layer 2
It moves through the gap between and and is finally introduced into the analytical column 7. Further, a heat block portion 3 for heating the glass insert 1 is provided outside the glass insert 1.

As a method of forming the heat resistant resin layer 2, a method of inserting a tube of heat resistant resin into the inner surface of the glass insert 1; a method of fusing a sheet of heat resistant resin to the inner surface of the glass insert 1 Etc.

The tube of the heat resistant resin is produced by, for example, extrusion molding. The outer diameter of this tube is preferably 0.1 mm smaller than the inner diameter of the glass insert in consideration of ease of insertion into the glass insert,
The length is 1-2 mm from the length of the glass insert, considering that it expands and extends in the length direction during use.
It is preferable to make it short. In addition, the thickness of the tube is 1
2 mm is preferable. In addition, the tube may be cooled to shrink the diameter if it is difficult to insert into the glass insert. The tube of the heat-resistant resin may be obtained by cutting the inside of an extrusion-molded or injection-molded rod and subjecting it to a tube-shaped secondary processing.

Examples of the heat resistant resin include polytetrafluoroethylene (PTF) represented by the formula (1).
E), tetrafluoroethylene-hexafluoropropylene copolymer (PEP) represented by formula (2), formula (3)
And a tetrafluoroethylene-perfluoro (alkyl vinyl ether) copolymer (PFA) represented by

[0011]

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[0012]

The present invention will be described below with reference to examples. (Example 1) Polytetrafluoroethylene (PTFE)
Was used to extrude a tube having an outer diameter of 4 mm, an inner diameter of 3 mm and a length of 78 mm, and the tube was inserted into a glass insert. This insert was attached to a gas chromatograph sample injection port, and a hexane solution of nitroglycerin was used as a sample having a glass adsorbing property, and the performance was evaluated under the following analysis conditions. Inlet temperature: 180 ° C, Detector: Electron capture type detector, Detector temperature: 200 ° C Analysis column length: 30 mm, Inner diameter: 0.32 mm, Thickness: 0.25 μm Analysis column temperature: 50 ° C for 1 minute After holding, the temperature was raised to 200 ° C. at a temperature rising rate of 10 ° C./min. Carrier gas: Helium Make-up gas: Nitrogen Injection method: splitless method, injection amount: 10 pg

Example 2 Using tetrafluoroethylene-hexafluoropropylene copolymer (PEP),
A tube having an outer diameter of 4 mm, an inner diameter of 3 mm and a length of 78 mm was molded and inserted into a glass insert having an outer diameter of 6 mm, an inner diameter of 4 mm and a length of 78 mm. The insert was attached to the gas chromatograph sample inlet, and the performance was evaluated under the same analysis conditions as in Example 1.

(Comparative Example 1) The performance was evaluated under the same analytical conditions as in Example 1 without inserting a tube of heat resistant resin into a glass insert having an outer diameter of 6 mm, an inner diameter of 4 mm and a length of 78 mm.

[0015]

[Table 1]

[0016]

The insert for the sample inlet of the gas chromatograph of the present invention has the above-mentioned constitution, and when the analysis of the sample having the glass adsorbing property is carried out by the gas chromatograph, the sample is adsorbed by the inner wall surface of the insert. Since the average value of the peak areas was large, the reproducibility when used repeatedly was good.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an insert for a sample injection port of a gas chromatograph of the present invention.

FIG. 2 is a vertical cross-sectional view showing a glass insert into which a tube of heat resistant resin is inserted.

[Explanation of symbols]

 1 Glass Insert 2 Heat Resistant Resin Layer 3 Heat Block Part 4 Septum 5 Septum Nut 6 Carrier Gas Inlet 7 Analytical Column

Claims (1)

[Claims] 1. A glass insert having a separation analytical column connected to one end and a septum attached to the other end, a heat block portion for heating the glass insert, and a carrier gas inlet opening to the glass insert. A sample inlet of a gas chromatograph having a heat-resistant resin layer formed on an inner surface of the glass insert.