JPH0464585B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to an automatic sample injection device for a capillary column in a gas chromatograph.

(b) Conventional technology and problems to be solved In recent years, compared to analysis using packed columns,
Analyzes using capillary columns, which have much higher separation capabilities, are increasing, but problems have been pointed out with the conventional split injection method, such as low quantitative performance and unsuitability for analysis of trace components. For this reason, various splitless injection methods have been developed to perform microanalysis using capillary columns, but the most ideal method is to directly inject the sample as a liquid into the capillary column. This is a cooled on-column method.

With this method, the solvent peak shows a sharp cut with little tailing, and high quantitative performance equivalent to that of a packed column can be obtained from low-boiling point components to high-boiling point components. It has the excellent feature of not decomposing or reacting at all.

However, the tip of the microsyringe needle used in this cooled on-column method has an inner diameter of 0.2~
This part is made of an ultra-thin silica capillary (outer diameter: 0.17 mm) in order to be inserted into a 0.5 mm capillary column, so it requires skill to operate during injection. Furthermore, to date, only devices with a diameter of 0.53 mm or more have been developed that can be connected to a liquid autosampler for automatic operation, and for diameters smaller than that, all injection operations were performed by hand. This is because in conventional autosamplers, the syringe moves and the sample is scooped up from a vial sealed with a silicone or other rubber stopper set on a turntable by penetrating the rubber stopper with a needle. This is because a capillary needle cannot penetrate this rubber stopper, and a viscous sample cannot be scooped up sufficiently.

(C) Means for Solving the Problems The present invention provides an automatic on-column injection device for a capillary column that makes it possible to fully automatically perform the process from collecting a liquid sample to injecting the sample into a capillary column. , a sample supply path connected to a sample pumping device is communicated with a syringe, a syringe valve piston is provided at one end of the syringe, one end of a needle is fitted into the other end, the needle is supported by the syringe piston, and the other end is fitted with a syringe valve piston. The sample injection port is characterized by being able to be placed in and inserted freely into a cleaner part installed opposite to the sample injection port, while the sample injection port has a packing at the end of the injection tube, and the insertion part of the packing can be opened and closed by air. shall be.

(D) Embodiment The sample pressure feeding device A comprises a sample bottle 1, a probe 2 inserted therein, a gas supply pipe 3, a piston 4 communicating therewith, and a gas supply path 5. The sample stored in the sample bottle 1 is forced into the supply path by the gas pressure from the probe 2 as the piston 4 descends. Using this piston 4, the sample flow time is appropriately set and the sample is fed. Samples may be taken directly from the sample line without the use of sample bottles. Sample injection device B is constructed as follows. That is, a syringe valve piston 8 is configured to be able to move in and out of a syringe valve 7 of a syringe 6 that communicates with the sample supply path 3 . The syringe valve piston 8 is air-driven within the cylinder 9. A needle 10 is supported by a syringe piston 11, and its upper end is inserted into the syringe 6, and its lower end is inserted into a cleaner section 12 of a sample injection port C, which will be described later. The cylinder 9 is moved up and down by an injection piston 13 driven by a syringe piston 11.

After flowing the sample according to the set time, when the syringe valve piston 8 is closed, the sample is sealed in the microsyringe 6. Then, the needle 10 is inserted into the sample injection port C and the sample is injected. A cleaner part 12 is provided at the front end of the sample injection port C, and the cleaner part 12 is connected to the purge gas injection port 1.
4 and a discharge port 15 are provided, and the opening thereof is sealed by providing a packing 16, and the tip of the needle 10 positioned inside thereof is always purged.
The sample injection port C is provided with a through hole 17, a cylindrical body 18 communicating with the through hole 17, and an injection tube 19 following the through hole 17. 20
21 is an air supply port communicating with the cylindrical body 18 and corresponding to the gap 23, and 21 is a carrier gas supply port communicating with the injection pipe 19. The upper end of the cylinder 22 is in sliding contact with the inside of the cylindrical body 18, and the lower end thereof is in sliding contact with the cylindrical body 18.
It is formed thinner and a gap 23 is formed between it and the cylindrical body 18. A spring 24 is located within the cylindrical body 18 between its upper end and the cylinder 22, and presses the cylinder 22 downward. 25 is a packing, which is located in the lower part of the cylinder 22 in the cylindrical body 18, and has an insertion part 26 for the needle 10, such as a through hole or a split groove.
is formed. 27 is a through hole provided in the cylinder 22, and the through hole 17, the cylinder through hole 27, and the injection pipe 19 are arranged in a line. 28 is a stopper for needle 10, 29 is a column oven,
30 is a capillary column communicating with the injection pipe, and 31 is a cooling air inlet.

In order to inject the sample, the tip of the needle 10 is lowered by the lowering of the syringe piston 11 and reaches the through hole 17 . At this time, air is supplied from the air supply port 20, enters the gap 23, and enters the cylinder 22.
is pushed up, and the spring 24 is compressed by the force. At the same time, the pressure on the packing 25 is released, the packing 25 returns to its original state, and the insertion portion 26 of the needle 10 opens. There, the needle 10 descends, passes through the through hole 17, the through hole 27 of the cylinder 22, and the insertion portion 26 of the packing 25, and is inserted into the injection tube 19. Once the needle 10 has descended to a certain position, the stopper 28 stops the needle 10 from further descending. cylinder 22 due to air supply stop
is pushed down by the spring 24, and the packing 25 is sealed. At this time, the upper end of the needle 10 rises above the syringe 6, and the sample in the syringe 6 is sent to the injection tube 19 through the needle 10 and inserted into the capillary column 30 by the amount of rise. Next, the needle 10 is raised and withdrawn, and the injection operation is completed.

(E) Effects of the Invention According to the present invention as described above, a sample flow path connected to a sample pressure feeding device is communicated with a syringe, a syringe valve piston is provided at one end of the syringe, and one end of a needle is fitted into the other end. At the same time, the needle is supported by the syringe piston, and the other end is placed in a cleaner part installed opposite to the sample injection port.
On the other hand, the sample injection port is characterized by a packing provided at the end of the injection tube, and the insertion part of the packing can be opened and closed by air, so that the sample injection is completely automated and the liquid sample can be inserted freely. can be directly injected directly into a capillary column, especially for 0.25
It became possible to use columns as thin as mm, expanding the scope of their use, and making it extremely easy to use the cooled-on-column method, which had a great effect on trace analysis.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram of a pressure feeding device that is a part of the present invention, FIGS. 2 to 4 are schematic explanatory diagrams of an automatic injection mechanism showing the operating order, and FIG. 5 is a schematic front view of the injection mechanism. 6 to 8 are schematic explanatory diagrams showing the operating sequence of the injection port device. 1... Sample bottle, 2... Probe, 3... Sample supply tube, 4... Piston, 5... Supply path, 6...
Syringe, 7...Syringe valve, 8...Syringe valve piston, 9, 22...Cylinder, 1
0...Needle, 11...Syringe piston, 1
2... Cleaner section, 13... Inject piston, 14... Purge gas inlet, 15... Discharge port, 16... Mouth packing, 17, 27... Through hole, 18... Cylindrical body, 19... ...Injection tube, 20...
Air supply port, 21...Carrier gas supply port,
23... Gap, 24... Spring, 25... Packing, 26... Insertion part, 28... Stopper, 29... Column oven, 30... Capillary column, 31... Cooling air inlet.

Claims (1)

[Claims] 1. A sample supply path connected to a sample pressure feeding device is communicated with a syringe, a syringe valve piston is provided at one end of the syringe, and one end of a needle is fitted into the other end, and the needle is supported by the syringe piston, and the other end is fitted with a syringe valve piston. The sample injection port is characterized by being able to be placed in and inserted freely into a cleaner part installed opposite to the sample injection port, while the sample injection port has a packing at the end of the injection tube, and the insertion part of the packing can be opened and closed by air. Automatic sample injection device for capillary columns.