JP2000179714A - Flow passage switching device and gas chromatograph - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flow passage switching device capable of suitably using for switching a flow passage by a Deans system, and provide a chromatograph in which the flow passage switching device is used. SOLUTION: This device is provided with two flow passage 1a, 1b and a common flow passage c-d-e led to those flow passages, and end parts of two flow passages 1a, 1b are closed by abutting tip ends of needles 4, 4 capable of traveling forward and backward. In a flow passage switching device, one of two flow passages 1a, 1b is controlled in an opening condition, and the other one is controlled in a closing condition. A chromatograph is provided with the flow passage switching device on the gas flow passage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow path switching device and a gas chromatograph, and more particularly, to a flow path switching method capable of suppressing pressure fluctuations at the time of flow path switching to the utmost limit and having high time accuracy. The present invention relates to a flow path switching device that can be used and a gas chromatograph using the flow path switching device.

[0002]

2. Description of the Related Art For example, multidimensional (M)
D) In the case of gas chromatography, a Deans system in which a flow path is switched according to a makeup gas flow is employed. FIG. 5 is an explanatory view of an example of the conventional flow path switching by the Deans method. The flow path switching is performed as follows.

When the three-way valve (20) is opened to the flow path side shown by the solid line, the makeup gas (M) passes through the flow path (21) at the branch (r) in the (L) direction and at the branch. (Q)
Divided into sides. As a result, the sample gas (S) introduced from the flow path (23) is guided in the (R) direction by the make-up gas (M) at the branch (q). Meanwhile, 3
When the one-way valve (20) is switched to open to the flow path side indicated by the dashed line, the makeup gas (M)
Via (2), the light is divided at the branch (p) into the (R) direction and the branch (q). As a result, the sample gas (S) introduced from the channel (23) is guided in the (L) direction by the make-up gas (M) at the branch (q). Usually, the three-way valve (20) for switching the flow path of the makeup gas (M) is operated by a motor (not shown).

In addition to the above, there is also known a Deans system in which solenoid valves are provided in the flow paths (21) and (22) instead of the three-way valve (20).

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a flow path switching device which can be suitably used for the flow path switching by the Deans method as described above, and a gas chromatograph using the flow path switching device. Is to do.

[0006]

That is, the first aspect of the present invention is as follows.
The gist of the invention has two flow paths and a common flow path communicating with these flow paths, the ends of the two flow paths are closed by abutment of a needle tip which can be advanced and retracted, and one needle By the operation described above, one of the two flow paths can be controlled to be open and the other can be controlled to be closed.

[0007] A second aspect of the present invention resides in a gas chromatograph comprising a gas flow path provided with the above-described flow path switching device.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is an explanatory diagram of an example of a flow path switching device of the present invention, FIGS. 2 and 3 are explanatory diagrams of an example of a preparative gas chromatograph of the present invention, and FIG. 4 is another example of a gas chromatograph of the present invention. FIG. Since the flow switching device shown in FIG. 1 includes the same left and right elements, in the following description, the same elements will be described using only one element unless necessary. FIG.
In FIG. 3 and FIG. 3, the channel switching device shown in FIG. 1 is omitted for convenience.

First, a flow path switching device (hereinafter, abbreviated as device) of the present invention will be described. The apparatus of the present invention is suitably used particularly for flow path switching by the Deans method in a gas chromatograph. In this case, the device of the present invention has a function of switching the flow path of the makeup gas.

The device (10) of the present invention comprises two flow paths (1
a) and (1b) and a common flow path (c-d-e) communicating with these flow paths. These flow paths are (c)-
(D)-(1a)-/ (c)-(e)-(1b), so that the makeup gas (M) introduced from the common flow path (c-d-e) is switched. Switching of the flow path is performed. In the following description, the common flow path (c-
de) may be represented by code (c).

The ends of the two flow paths (1a) and (1b) are closed by the contact of the tips of the needles which can be moved forward and backward. In the case of the device shown in FIG. 1, one end of the flow path (1a) is inserted and fixed from one end of the opening / closing section envelope (2), and the support pipe (3) is inserted into the other end of the opening / closing section envelope (2). Are connected to each other, and a needle (4) capable of moving forward and backward is inserted into the inside of the support tube (3), so that the tip of the needle (4) comes into contact with the end of the flow path (1a). . Although the shape of the opening / closing section enclosure (2) is not particularly limited, the volume is preferably as small as possible from the viewpoint of reducing the dead space.

In the apparatus shown in FIG. 1, two opening / closing sections (2) are used, but one opening / closing section enclosure (2) is commonly used and two needles (4) are used. , The flow path (1a), the flow path (1b), and the common flow path (c) are connected to one opening / closing unit enclosure (2), and the common flow path (c) and the flow path (1a) are opened. , Common channel (c) and channel (1b)
May be configured to be switchable between the open state and the open state.

When inserting the needle (4) into the inside of the support tube (3), a sealing member (8) such as packing is used. From the viewpoint of reducing the dead space, the seal member (8) is preferably arranged at a position close to the opening / closing section enclosure (2).

The means for advancing and retracting the needle (4) is not particularly limited, but is preferably constructed as in the device shown in FIG. That is, in the needle driving unit shown in FIG. 1, the base end of the needle (4) is fixed to the piston (6) disposed in the cylinder (5), and the operating range of the piston (6) is Has gas supply ports (7A) and (7B) on both outer sides of the cylinder, and each gas supply port is alternately connected to the gas supply port of another cylinder, and each set: (7A) / (7B) It is connected to a common operation gas supply channel (9).

As other needle driving units, for example, a spring is installed above the piston (6) inside the cylinder (5), a control gas flow path is installed only below the piston (6), and A method may be adopted in which a control gas is introduced from the lower portion to be open, and a control gas is discharged to be closed by a spring. Conversely, a spring is installed below the piston (6) inside the cylinder (5), a control gas flow path is installed only above the piston (6), and control gas is introduced from above. For example, a method may be adopted in which a closed state is established when the control gas is discharged, and an open state is established by a spring when the control gas is discharged.

Further, an electromagnetic valve system may be employed without using a control gas for driving the needle (4). in this case,
An electromagnet may be installed in the upper part and lower part inside the cylinder (5), and the piston (6) may be formed of a material attracted by the magnet such as iron, and the piston (6) may be driven by turning on / off the electromagnet. Alternatively, the piston (6) itself may be an electromagnet, and a magnet such as an electromagnet may be arranged at the upper and lower portions inside the cylinder (1), and driven by utilizing attraction and repulsion.

However, in the case of the cylinder type needle driving unit shown in FIG. 1, the operation is highly reliable.
This is advantageous in that control of the piston speed is easy, the piston speed can be set in a wide range, and safety is high without using a strong current.

The apparatus of the present invention configured as described above can control one of the two flow paths to be open and the other to be closed by operating one needle, that is, for example, In the case of the apparatus shown in FIG. 1, by supplying the operation gas from the left operation gas supply flow path (9), the left needle (4) is lowered by the piston (6) to the flow path (1a). The needle (4) on the right side is raised by the piston (6) and comes off the flow path (1b). At this time, the gas in each cylinder compressed by the rise and fall of each piston is supplied to the gas supply port (7
B) and the gas supply port (7A) on the right side, and is discharged through the operation gas supply channel (9) on the right side.

The left and right operation gas supply passages (9) as described above.
The supply and discharge of the operation gas to and from the gas can be easily performed by, for example, a four-way switching valve (not shown). As other means, a solenoid valve may be used, or a common operation gas supply flow path (9) is not provided,
All the gas supply ports (7A) and (7B) may be made independent and connected to different solenoid valves to control switching of the flow path of the control gas.

The channel switching device of the present invention according to the present invention comprises:
The flow paths (1a) and (1b) and the common flow path (c) can be used without being limited to the gas flow direction.

Next, the gas chromatograph of the present invention will be described. The gas chromatograph of the present invention is characterized by comprising the above-mentioned flow path switching device in a gas flow path. Therefore, the main body may be any type of gas chromatograph as long as it is a gas chromatograph provided with a flow path having one or more branch points in three directions. For example, an MD gas chromatograph, a preparative gas chromatograph, a gas chromatograph having a gas flow path switching function, and the like are included.

In the case of the MD gas chromatograph and the preparative gas chromatograph, a specific fraction or component separated by the column branches off from a normal flow path and is guided to the flow path side where a cooling trap is installed to fractionate or separate. Taken. Furthermore, in the case of an MD gas chromatograph, the trapped fraction is vaporized again when introduced into the column for re-separation.

In the case of a gas chromatograph having a gas flow switching function, a main component (solvent) separated by a column is used.
Is discharged to the side of the flow path branched from the normal flow path. In addition, all the components of the sample (or constituent components) separated by the column are introduced into the detector,
When an infrared detector (IRD) and an atomic emission detector (AED) are used, the main component (solvent) remains and adversely affects detection (reduction in sensitivity and quantitativeness). The main component (solvent) is removed by the above gas flow switching function.

The gas chromatographs shown in FIGS. 2 and 3 are preparative gas chromatographs. The basic configuration of this gas chromatograph is the same as that of a conventionally known gas chromatograph.

First, in the state shown in FIG. 2 (analysis state), He (makeup gas) supplied from the He cylinder (11) via the pressure regulator (12) is supplied to the gas flow switching device. (C), the cylinder (5) on the left side, and the branch point (r) via the flow path (1a) (that is, the gas flow path switching device is a reverse configuration of the configuration shown in FIG. 1). ing). Then, the makeup gas that has reached the branch point (r) is diverted to the cooling trap (13) side and the branch point (q) side. Therefore, the sample inlet (14)
Is injected along with He (carrier gas) supplied from the He cylinder (15) via the pressure regulator (16) and reaches the branch point (q) via the separation column (17). After reaching, the detector gas (1) passes through the branch point (p) by the makeup gas diverted to the branch point (q) side.
8).

Next, immediately before the target component separated in the separation column (17) reaches the branch point (q), the gas flow path switching device is operated to switch the flow path of the makeup gas.
(Fractionation state). That is, the makeup gas reaches the branch point (p) via the common flow path (c), the right cylinder (5), and the flow path (1b) of the gas flow path switching apparatus (gas flow switching apparatus). Is the mode shown in FIG. 1). Then, the makeup gas reaching the branch point (p) is diverted to the detector (18) side and the branch point (q) side. Therefore, the target component separated at the separation column (17) and reaching the branch point (q) is flushed to the cooling trap (13) via the branch point (r).

After the target component has passed the branch point (r), the gas flow switching device is operated to switch the flow path of the make-up gas to return to the state shown in FIG. The symbol (19) in FIGS. 2 and 3 indicates a column oven.

The above-described apparatus of the present invention is suitably used for a gas chromatograph provided with a column (not shown) having a small flow rate before (L) of the flow path (24) as shown in FIG. Is done. On the flow path (24), a cooling trap (13) or the like is provided as a sample trap means if necessary. Right cylinder (5) closed, left cylinder (5)
When the sample is introduced from the (R) side of the channel (24) in the open state, the sample is held in the cooling trap (13) via the branch point (p). The carrier gas passes through the cooling trap (13) and the branch point (r), and a part of the carrier gas passes through the channel (1a) and the left channel (5) to the common channel (c), and then to another channel (c). A part reaches the (L) side of the flow path (24).

Thereafter, when the right cylinder (5) is open and the left cylinder (5) is closed, a carrier gas is introduced from the (R) side of the flow path (24) and held in the cooling trap (13). When the sample is opened, all the sample passes through the branch point (r) and passes through (L) of the channel (24).
Carried to the side. The carrier gas passes through the branch point (p), a part of which flows into the common flow path (c) via the flow path (1b) and the right cylinder (5), and another part is a cooling trap. After passing through (13), the sample reaches the (L) side of the flow path (24) via the branch point (r) while carrying the sample as described above. As described above, in the flow path switching device of the present invention, since a part of the carrier gas is discharged to the common flow path (c), the flow path (2
It is suitably used when a column (not shown) having a small flow rate is provided downstream of (L) in 4).

[0030]

According to the flow path switching device of the present invention, the following effects can be obtained.

(1) Active sites that cause decomposition or adsorption of a flowing substance at a portion provided for switching a flow path are removed.

(2) The configuration in which the tip of the needle which can be advanced and retracted contacts the end of the flow path to switch between the closed state and the open state means that the tip of the needle directly blocks the flow path. Therefore, the dead volume of the flow path at the time of switching (particularly at the time of closing) is substantially zero, and the switching speed is high.

(3) When two opening / closing sections are used, the internal pressure of each opening / closing section can be maintained at substantially the same pressure.
Pressure fluctuations at the time of switching between opening and closing can be suppressed to the utmost.

(4) When a needle drive unit of the cylinder type is used, the control gas used for operating the piston is independent of the switching flow path, and thus is subject to flow restriction due to the flow rate of the switching flow path. Operation speed can be increased to the utmost. As a result, it is possible to precisely switch the flow path at the target time. Therefore, in the gas chromatograph of the present invention, the target component can be efficiently and precisely fractionated.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an example of a flow path switching device of the present invention.

FIG. 2 is an explanatory view of an example of a preparative gas chromatograph of the present invention (analysis state).

FIG. 3 is an explanatory view of an example of a preparative gas chromatograph of the present invention (fractionation state).

FIG. 4 is a partial explanatory view of another example of the gas chromatograph of the present invention.

FIG. 5 is an explanatory diagram of an example of conventional flow path switching by the Deans method.

[Explanation of symbols]

 1a: Flow path 1b: Flow path cd-e: Common flow path 2: Opening / closing section enclosure 3: Support tube 4: Needle 5: Cylinder 6: Piston 7A: Gas supply port 7B: Gas supply port 8: Seal member 9: Operation gas supply flow path 10: Flow path switching device 11: He cylinder 12: Pressure regulator 13: Cooling trap 14: Sample injection port 15: He cylinder 16: Pressure regulator 17: Separation column 18: Detector 19: Column oven 20: Three-way valve 21 to 24: Channel M: Makeup gas S: Sample gas

Claims (3)

[Claims] The present invention has two flow paths and a common flow path communicating with these flow paths, and ends of the two flow paths are closed by abutment of a needle tip which can be moved forward and backward, and one of the flow paths is closed. A flow path switching device wherein one of the two flow paths can be controlled to be open and the other can be controlled to be closed by operating a needle. 2. The base end of each needle is fixed to a piston disposed in a cylinder, and each cylinder has gas supply ports (A) and (B) on both outer sides of the operating range of the piston. The flow path switching device according to claim 1, wherein the supply ports are alternately connected to gas supply ports of other cylinders, and are connected to a common operation gas supply flow path for each set. 3. A gas chromatograph comprising a gas flow path provided with the flow path switching device according to claim 1 or 2.