JPH09189691A - Multidirectional connector for gas chromatograph - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multidirectional connector with good maintenance property in which the broadening of a peak in a sample gas can be minimized as much as possible. SOLUTION: This connector has a branch connecting part 2 provided in a plurality of directions so as to be continued to the supplying point of a sample gas, a branched passage 3 having an inside diameter equal to or substantially equal to the inside diameter of a capillary column 4, and a column guide 5 for inserting the capillary column 4 by a prescribed length which is continued to the branched passage 3 and having an inside diameter slightly larger than the outer diameter of the capillary column 4. A cylindrical ferrule 7 having a tapered part 16, to which the capillary column 4 is inserted, is provided in such a manner that its cylinder bottom part 10 makes contact with the end part of the branch connecting part 2, and a nut member 11 is screwed to the branch connecting part 2 so as to enclose the ferrule 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas chromatograph multidirectional connector (hereinafter simply referred to as a multidirectional connector) for branching a sample gas supplied from one direction into multiple directions.

[0002]

2. Description of the Related Art A gas chromatograph is used to analyze hydrocarbons in automobile exhaust gas, but the number of hydrocarbon components contained in the exhaust gas is as large as 200 or more, and its boiling point range is also very wide. . Therefore, it takes as long as 40 minutes to separate and analyze these individual components by using only one separation column by utilizing the difference in boiling points.

The temperature of the column during separation may be increased to reduce the time it takes for all components to elute from the column. However, although this method can increase the speed, it has a problem that a component having a low boiling point, that is, an initial eluted component cannot be sufficiently separated. In other words, if you try to separate a multi-component sample with a wide range of boiling points in one column,
It is difficult to achieve both high speed and high separation.

As a solution to the above-mentioned problems, there has been proposed a system in which a gas chromatograph has multiple columns. In this method, as shown in FIG. 3, for example, four separation columns 33 are connected in parallel to each other in a flow path 32 on one end side of a cold trap 31, and a gas (hereinafter, referred to as a sample gas) transferred by a carrier gas from the cold trap 31 is connected. Is supplied to each separation column 33. In this figure, 34 is a FID (hydrogen flame ionization detector) provided in the subsequent stage of each separation column 33, 35 is a sample inlet, 36 is a carrier gas source,
37 is a vacuum pump.

As described above, one cold trap 3
When the sample gas from 1 is supplied to the four separation columns 33, a multidirectional connector having one flow path and four branch flow paths is required, and is shown by the reference numeral 38 in the one shown in FIG. It is provided in the part.

In the above multi-directional connector, it is necessary to make the carrier gas and the sample gas evenly flow through the four separation columns 33, the dead volume is as small as possible, and the maintainability is good. Those are preferable.

By the way, conventional multidirectional connectors include those made of glass or stainless steel. However, there is a problem that a glass column cannot be used for a stainless steel capillary column, and it is expensive and disposable. Further, in the case of stainless steel, conventionally, only the outer diameter of the connecting tube was a specific size.

Therefore, the inventor of this application has developed a multidirectional connector as shown in FIGS. 4 and 5. That is, in these drawings, 41 is a multi-directional connector made of, for example, stainless steel, and has a sample gas introduction portion (not shown) and four branch connection portions 42 provided in a direction perpendicular to the paper surface. . Inside the branch connection part 42, four branch flow passages 43 communicating with the sample gas introduction passage of the sample gas introduction portion and having a throttling function are provided, and at the other end side of each branch flow passage 43, a capillary column is provided. A column guide 45 for inserting 44 is provided. A female screw portion 42a is formed on the inner circumference of the end of each branch connection portion 42.

Further, 46 is a columnar ferrule made of graphite, for example, and having a tapered taper portion, and a hole 46a for inserting the capillary column 44 is formed in the axial direction of the ferrule. 47 is a push screw,
A male screw portion 47a that is screwed with the female screw portion 42a is formed, and a hole 47b for inserting the capillary column 44 is formed in the axial direction thereof.

In order to connect the capillary column 44 to the multidirectional connector 41, the capillary column 44 is inserted through the push screw 47 and the ferrule 46 in this order, and the tip end of the capillary column 44 is inserted into the column guide 45. By tightening the push screw 47, the ferrule 46
Is compressed and the hole 46a is contracted, so that the capillary column 44 is fixed in a predetermined connection state.

According to the multidirectional connector 41 having the above structure,
Since the sample gas can be distributed in four directions and the dead volume of the connection portion is smaller than that in the conventional case, it is possible to favorably prevent the spread of the peak in the sample gas.

[0012]

However, in the multi-directional connector 41, some room for improvement has been found. That is, in this multi-directional connector 41, the taper portion side of the ferrule 46 is connected to the branch connection portion 42.
Since it is configured to be close to the inner column guide 45, a dead volume d is inevitably generated between the column guide 45 and the capillary column 44, and it is necessary to make it completely zero or a state close thereto. However, there is a concern that the spread state of the peak will be affected by that amount.

In addition, when replacing the capillary column 44, the ferrule 46 may remain on the side of the branch connecting portion 42 even if the push screw 47 is loosened, and the ferrule 46 cannot be easily taken out. However, excessive external pressure may be applied to the capillary column 44, which may be damaged, and the branch passage 43 may be clogged by the ferrule 46.

The present invention has been made in view of the above matters, and an object thereof is to reduce dead volume to a state of zero or close to that as much as possible, and to facilitate removal of a ferrule to obtain a sample. It is an object of the present invention to provide a multidirectional connector that can suppress the spread of peaks in gas as much as possible and that has good maintainability.

[0015]

In order to achieve the above object, the present invention provides a multidirectional connector for branching a sample gas supplied from one direction in multiple directions.
Branch connection parts are provided in a plurality of directions so as to be continuous with the sample gas supply point, and inside each branch connection part, a branch flow path having the same or substantially the same inner diameter as the inner diameter of the capillary column, and the branch flow path Connected to the column, has an inner diameter slightly larger than the outer diameter of the capillary column, and is provided with a column guide for inserting the capillary column for a predetermined length, while allowing the capillary column to pass therethrough and having a columnar shape with a tapered taper portion. The ferrule is provided such that the bottom of the columnar body is in contact with the end of the branch connecting portion, and the nut member is screwed to the branch connecting portion so as to wrap the ferrule.

In the multidirectional connector having the above structure, the capillary column can be connected to the branch flow passage with almost no dead volume. When the nut member is loosened to replace the capillary column, the ferrule will stick to the nut member, so the ferrule will not remain in the connector, thus damaging the capillary column or creating a branch flow path. No more clogging with ferrules.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION A preferred embodiment of the present invention will be described below with reference to FIGS.

First, in FIG. 1, reference numeral 1 denotes a multi-directional connector made of, for example, stainless steel, which has a sample gas introduction portion (not shown) provided in a direction perpendicular to the paper surface and four branch connection portions 2. doing. As shown in FIG. 2, four branch flow passages 3 having a throttling function that communicate with the sample gas introduction passages of the sample gas introduction portion are provided inside each branch connection portion 2. A column guide 5 for inserting the capillary column 4 is provided on the other end side. Further, a male screw portion 6 is formed on the outside of each branch connection portion 2.

The lengths and inner diameters of the respective branch channels 3 are set so that they have the same flow rate characteristics. The branch channel 3 is configured to have the same or almost the same inner diameter as the inner diameter of the capillary column 4. Further, the column guide 5 has an inner diameter slightly larger than the outer diameter of the capillary column 4, and is configured so that the capillary column 4 can be inserted by a predetermined length.

Reference numeral 7 is, for example, graphite, which is a columnar ferrule having a tapered taper portion 8, and a hole 9 for inserting the capillary column 4 in the axial center thereof from the taper portion 8 side to the bottom of the cylinder body. It is opened on the 10th side.

Reference numeral 11 denotes a nut member that includes the ferrule 7 and is screwed to the branch connecting portion 2. The inner surface side of the nut member 11 has the branch connecting portion 2
And formed so as to correspond to the outer periphery of the ferrule 7,
A female screw portion 12 that is screwed into the male screw portion 6 of the branch connection portion 2 is formed on the inner periphery on one end side, and a hole 14 having a diameter (slightly larger) that is substantially the same as the outer diameter of the capillary column 4 is formed on the bottom portion 13 on the other end side. It has been opened. Reference numeral 15 is a straight inner wall of the nut member 11, and 16 is a tapered inner wall surface having the same slope as the tapered portion 8.

An example of a procedure for connecting the capillary column 4 to the branch connecting portion 2 of the multidirectional connector 1 having the above structure will be described.

First, the tip end side of the capillary column 4 is passed from the hole 14 side of the nut member 11 toward the female screw portion 12 side.

Next, the tip side of the capillary column 4 is
The ferrule 7 is passed from the tapered portion 8 side toward the columnar bottom portion 10.

Then, the tip of the capillary column 4 protruding from the bottom 10 of the cylindrical body of the ferrule 7 is inserted into the column guide 5 of the branch connecting portion 2, and the tip is placed between the column guide 5 and the branch flow path 3. Abut the wall 17.

In this state, the nut member 11 is attached to the branch connecting portion 2 so as to include the ferrule 7 therein,
Screw into this. Since the tapered portion 8 is formed on the outer periphery of the ferrule 7 on the side where the capillary column 4 is inserted, the force due to the screwing is applied to the ferrule 7, whereby the hole 9 of the ferrule 7 is contracted, and the capillary column 4 is It is sandwiched by the walls around the hole 9 and is rigidly connected to the branch connection 2.

In the connected state, the tip end side of the capillary column 4 abuts the step wall 17 in the branch connection part 2, so that no gap is formed between the capillary column 4 and the branch flow passage 2, and Since there is almost no gap between the capillary column 4 and the column guide 5, the dead volume at the connection portion is almost zero or close to this.

Therefore, this multidirectional connector 1 is shown in FIG.
In the gas chromatograph incorporated in the portion indicated by reference numeral 38, the spread of the peak in the sample gas is suppressed as much as possible, and good analysis results can be obtained.

When the capillary column 4 in the connected state is removed from the branch connecting portion 2, the nut member 11 is rotated in the loosening direction. In this case, the ferrule 7
Since the flat cylindrical body bottom portion 10 is simply in contact with the flat end portion 18 of the branch connection portion 2, the ferrule 7 is attached to the nut member 11 as the nut member 11 rotates, It comes off easily. Therefore, the capillary column 4 can be easily removed, and the capillary column 4 will not be damaged or the branch channel 3 will not be clogged.

Further, the multidirectional connector 1 having the above construction is strong because it is made of metal such as stainless steel, and when any of the capillary columns 4 is broken or cracked during use, It is only necessary to replace the capillary column 4 with a new one, maintenance is very simple, and running costs can be greatly reduced.

The present invention is not limited to the above-mentioned embodiment, and it goes without saying that the number of branch connection portions 2 can be set to an arbitrary number of 2 or more.

[0032]

The present invention is embodied in the above-described embodiment and has the following effects.

The capillary column can be connected to the branch connection portion with almost no dead volume, and the ferrule can be easily taken out without damaging the removal of the capillary column. It can be done easily and the branch flow path is not clogged.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of a multidirectional connector of the present invention.

FIG. 2 is an exploded cross-sectional view showing a main part of the multidirectional connector.

FIG. 3 is a configuration diagram showing an example of a gas chromatograph in which the multidirectional connector invention is incorporated.

FIG. 4 is a partial cross-sectional plan view of the multidirectional connector developed in the previous stage of the present invention.

FIG. 5 is a cross-sectional view showing a main part of the multidirectional connector.

[Explanation of symbols]

2 ... Branch connection part, 3 ... Branch flow path, 4 ... Capillary column, 5 ... Column guide, 7 ... Ferrule, 8 ... Tapered taper part, 10 ... Cylindrical bottom part, 11 ... Nut member.

Claims (1)

[Claims] 1. A multidirectional connector for a gas chromatograph for branching a sample gas supplied from one direction in multiple directions, wherein branch connection parts are provided in a plurality of directions so as to be continuous with a supply point of the sample gas. Inside each branch connection part, a branch channel having the same or almost the same inner diameter as the inner diameter of the capillary column, and connected to this branch channel,
While having an inner diameter slightly larger than the outer diameter of the capillary column and providing a column guide for inserting the capillary column by a predetermined length, while inserting the capillary column, a cylindrical ferrule having a tapered taper portion, A multidirectional connector for a gas chromatograph, characterized in that the bottom of the columnar body is provided so as to abut the end of the branch connecting portion, and a nut member is screwed to the branch connecting portion so as to wrap the ferrule.