JPH063343A - Gas chromatographic device - Google Patents

Abstract

PURPOSE:To obtain accurate analyzed results from a sample containing an interfering substance for a long time without performing pretreatment for removing the interfering substance by heating the sample injected into a preheating tube from one end of the tube in the preheating tube and sending vaporized components to a main-body column together with a carrier gas. CONSTITUTION:A preheating tube 4 is connected to the gas inlet section of a main-body column 2 through a repeating tube 6 on one side and to a sample injecting section 1 and carrier gas supplying device 8 through a branched tube 7 on the other side, with its U-shaped bent section 5 being positioned downward. The tune 4 and part of the tube 7 are housed in a heating device 9 equipped with a temperature controller. A sample is injected from the section 1 while a carrier gas is supplied at a fixed rate from the device 8. The injected sample drops into the tube 4 and most of the sample reaches the bent section 5 where the sample is heated. Whereas volatile components are quickly vaporized, nonvolatile components are gradually carbonized and most of them adhere to the tube wall of the section 5. Therefore, the nonvolatile components do not go to the column 2 nor contaminate the column 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas chromatograph, and more particularly to a gas chromatograph suitable for analyzing volatile fatty acids coexisting with non-volatile interfering substances.

[0002]

2. Description of the Related Art When volatile fatty acids in a sample in which organic substances having a large molecular weight such as sugar and protein coexist with volatile fatty acids are to be determined by gas chromatography,
When the sample is directly injected into the column, the nonvolatile high molecular weight substance contaminates the column, which hinders accurate analysis and shortens the life of the column. For this reason, conventionally, it has been necessary to perform a pretreatment for removing an interfering substance in a sample and then apply it to a gas chromatograph. However, a simple process is not enough to completely remove the interfering substance,
Therefore, there is a problem that a complicated process and a considerably large amount of sample are required, and a part of sample components may be altered or volatilized during the pretreatment, which causes an error.

There is also provided an apparatus in which a preheating tube is installed directly above the column, a sample is injected therein, and only the components heated by the preheating tube and vaporized are sent to the column by a carrier gas, but some of them are also provided. However, there was a drawback that the sample of (1) directly entered the column.

[0004]

Therefore, according to the present invention, even if a sample containing an interfering substance as described above is analyzed as it is, an accurate analysis value can be obtained for a long time, and a pretreatment for removing the interfering substance is unnecessary. It is intended to provide a gas chromatograph device.

[0005]

A preheating tube having a U-shaped bent portion is placed with the bent portion facing down between a sample injection section and a main body column, and a heating device for the preheating tube is installed.
The sample is injected from one end of the preheating tube, the injected sample is heated in the preheating tube, and the vaporized components are sent to the main body column from the other end of the preheating tube by the carrier gas.

[0006]

In this gas chromatograph, the sample injected from one end of the preheating tube having the U-shaped bent portion is heated in the preheating tube, only the volatile components in the sample are vaporized, and the main gas is applied to the main column by the carrier gas. Sent in. High molecular weight organics such as sugars and proteins are
As a result of being stagnant at the bent portion and being heated, it gradually carbonizes and adheres to the pipe wall. Since the gas outlet of the preheating pipe is at a high position,
No carbonized (or pre-carbonized) high molecular weight non-volatile components are pumped into the body column and contaminate the column,
The column exerts a high degree of resolution for a long time to give accurate analytical results.

[0007]

The present invention will be described below with reference to the illustrated embodiments. In the embodiment of FIG. 1, the sample injection part 1, the main body column 2, the detection electrode 3 and the like are not particularly different from those in the conventional gas chromatograph device. The preheating pipe 4 characteristic of the present invention has a U-shaped bent portion 5 at the bottom, one end to a gas inlet portion of the main body column 2 via a relay pipe 6, and the other end to a sample injection portion via a branch pipe 7. 1 and a carrier gas supply device 8 respectively. A part of the preheating pipe 4 and the branch pipe 7 is housed in a heating device 9 with a temperature control device.

When performing analysis by this apparatus, the heating device 9 heats the preheating tube 4 to a temperature sufficient to vaporize the volatile component to be quantified. Then, the sample is injected from the sample injection part 1 while the carrier gas is supplied from the carrier gas supply device 8 at a constant flow rate. The injected sample falls into the preheating tube 4, and some components are vaporized during the fall, but most reach the U-shaped bent portion 5 and are heated there. The volatile components are quickly vaporized and sent to the main body column 2 by the carrier gas, but the non-volatile components are gradually carbonized and most of them adhere to the tube wall of the bent portion 5. Since the connecting portion with the main body column 2 is located higher than the U-shaped bent portion 5, non-volatile components and their carbides are not sent to the main body column 2 and contaminate the column.

When the above-mentioned device was used to measure the concentration of volatile fatty acids in the digested liquid (containing undecomposed sugar, soluble protein, etc.) obtained by anaerobically digesting the waste sugar liquid,
The column was usable for 100 hours or more. For comparison, when the preheating tube 4 was replaced with an existing glass straight tube type preheating tube and used for the same analysis under the same conditions, the column was contaminated with the carrier in 10 hours and could not be calibrated.

[0010]

In the device of the present invention, it is possible to completely prevent the non-volatile interfering substance from entering the column and shortening the life of the column. Therefore, the sample containing the non-volatile interfering substance can be directly subjected to the gas chromatography. It becomes possible to carry out the analysis, and the time required for the analysis is shortened and the analysis operation is simplified.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a gas chromatograph apparatus of the present invention.

[Explanation of symbols]

1: Sample injection part 2: Main body column 3: Detection electrode 4: Preheating tube 5: U-shaped bent part 8: Carrier gas supply device 9: Heating device

Claims (1)

[Claims] 1. A preheating tube having a U-shaped bent portion is interposed between the sample injection part and the main body column with the bent portion facing down, and a heating device for the preheating tube is installed so that the sample is loaded from one end of the preheating tube. A gas chromatograph apparatus, characterized in that an injected sample is heated in a preheating tube and vaporized components are sent from the other end of the preheating tube to a main body column by a carrier gas.