JPS5939642Y2 - Gas chromatograph sample introduction section - Google Patents

Description

[Detailed description of the invention] This invention is a gas chromatograph sample configured to purge gas (septum bleed) that is generated from the septum of the sample introduction part of the gas chromatograph and has an adverse effect on the baseline of the gas chromatogram (septum bleed) to the outside of the apparatus. This is about the introduction.

The present invention relates to a sample introduction section using SEBU TIME, which has a narrow opening in the insertion part of a syringe for sample injection, and the opening is blocked by the syringe when the syringe is filled with slag. In this method, an inexpensive high-resistance purge tube with a needle-shaped tip is inserted into the septum to maintain a narrow opening, and the bleed can be extracted.

Conventionally, the sample introduction section of a gas chromatograph has a septum made of silicone rubber, etc., so that the sample can be easily injected with a syringe.Silicon rubber is mainly used because it has both heat resistance and gas sealing ability. However, especially when used at high temperatures of 250°C or higher, gas is generated from inside the silicone rubber and mixed into the carrier gas by diffusion, disturbing the baseline and causing problems such as ghost peaks. becomes.

As a countermeasure against this problem, various methods have been devised to discharge all or part of the septum bleed out of the flow path, or to change the septum to one made of a different material after sample injection.

For example, a fixed branch channel may be provided in the sample introduction section near the septum, and a fixed or variable flow channel high resistance tube may be attached to the branch channel.

In this way, a portion of the carrier gas is discharged to the outside from this branch flow path, and the septum bleed is also discharged along with it, so that the amount of septum bleed that enters the main flow path is reduced.

However, in this method, since the carrier gas is divided into two parts even when the sample is introduced, part of the sample is lost during sample injection.

To prevent this drawback, some channels are configured so that all the carrier gas enters the column only during sample injection, but in this case, a valve for switching the channel is required, which is expensive. suck.

Additionally, in order to minimize septum bleed, there is a sample introduction section that allows the silicone rubber septum to be replaced with a Teflon septum when not injecting a sample, but this is also expensive and Teflon septa are prone to gas leakage.

To overcome the various drawbacks mentioned above, and to ensure that the entire amount of the injected sample is introduced into the column during sample injection, and to easily remove the remaining septum bleed, the present invention has a thin tube at the insertion part of the sample injection syringe. An aperture is provided, and the aperture is intended to be used as a sample introduction portion of a septum which is closed by the syringe when the syringe is inserted.

The present invention will be explained below according to the drawings.

FIG. 1 is a cross-sectional view of the main part of the sample introduction section of the present invention, and is an explanatory diagram in which a flow path high resistance tube is inserted through the septum into the sample vaporization chamber of a gas chromatograph in order to maintain the septum with a narrow opening.

A silicone rubber septum 2 of any shape is attached to the front surface of a sample vaporization chamber 1 in a sample introduction section of a gas chromatograph with a cap nut 3.

This septum 2 is provided with a thin opening 4, and in this embodiment, in order to maintain this opening through the opening 4 of this septum 2, the tip of the flow path high resistance tube 5 is inserted into the flow path at 1. Contains 1.

At this time, the needle tip 7 of the needle tube 6 that laterally restricts the flow path high resistance tube 5 must be located adjacent to the septum 11 from the carrier gas inflow position 8 of the sample vaporization chamber 1; A sleeve 9 is placed over the needle tube 6 for positioning and reinforcement of the needle tube 6.

The needle tube 6 may be a normal syringe needle or the like, and a high resistance 10 is connected to the rear end of the needle tube 6 by brazing.

Most of the carrier gas flowing in from the carrier gas inflow position 8 advances into the sample vaporization chamber and enters the column, but a portion enters the inside of the needle tube 6 from the needle tip 7 and is discharged to the outside of the apparatus through the high resistance 10. Ru.

The gas generated from the septum 2 is blocked by the carrier gas flow and does not enter the sample vaporization chamber, but is discharged from the apparatus together with the purge gas flow.

When injecting a sample, the flow path high resistance tube 5 may be pulled out from the septum 2, and a sample injection syringe (not shown) may be inserted.

Therefore, during sample injection, the entire amount of carrier gas is sent to the column, and no part of the sample is discharged outside the apparatus.

The material, length, resistance size, resistance making force, connection method, etc. of this high resistance 10 can be arbitrarily selected.

Further, a fixed resistance or a variable resistance may be used.

Furthermore, the needle tip I may be positioned without using the sleeve 9, for example, by fixing a stopper 11 at an appropriate position on the needle tube 6 as shown in FIG.

Any other method may be used for positioning.

Further, although the needle tube 6 and the high resistance 10 are shown separately in FIG. 1, the needle tube 6 itself may have a high resistance.

FIG. 3 shows another modified embodiment of the needle tube for maintaining septum aperture.

In FIG. 3, the connection between the needle tube 6 and the high resistance 10 is through a socket 12 with a sleeve 9 attached, a nut 13, and a seal 1.
4. This is done by screwing using nibble 15.

Therefore, if the needle tip 7 becomes clogged with silicone rubber chips from the septum 2, loosen the nut 13 and use the high resistance 10
It can be pushed out.

Similarly, when the nut 13 is loosened, the gas seal by the gasket 14 at the rear end of the needle tube 6 is released, and the needle tube 6
Since the carrier gas also flows out from the gap between the high resistance 10 and the high resistance 10, the total amount of purge gas increases.

This means that the needle tube 6 itself is also used as a high resistance tube.

If the high resistance 10 is extracted in this state, the flow path resistance of the needle tube 6 decreases, so the purge gas flow rate increases continuously.

In other words, this type of flow resistance tube can be used both as a fixed resistor and as a variable resistor.

As is clear from the above explanation, according to the present invention, the syringe insertion part for sample injection has a thin opening, and the opening is closed by the syringe when the syringe is inserted. Since a septum is used and a needle-like tube (flow path high resistance tube) is used to maintain this opening, septum bleed in a gas chromatograph can be removed at low cost. Part of the gas is not exhausted outside the device, and the entire amount of the injected sample can be sent to the column.

In the above embodiment, a needle tube is used to maintain the opening of the septum, but there is no need to use the needle tube if there is no risk that the hole will be blocked by the material of the septum.

[Brief explanation of the drawing]

Fig. 1: Constituent countries of the sample introduction section of a gas chromatograph according to an embodiment of the present invention, Fig. 2: A diagram of a modification of the needle tube 6 of Fig. 1, Fig. 3: A modified example diagram of Figure 1,

Claims (1)

[Scope of utility model registration request] The sample introduction part of a gas chromatograph has a thin opening in the part of the septum into which the sample injection syringe is inserted.