JP2780370B2 - Automatic sample injector for gas chromatograph - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas chromatograph for analyzing various kinds of samples, and more particularly to an automatic sample injection device for a gas chromatograph using a capillary column.

[Prior Art] When injecting a sample with a gas chromatograph using a capillary column, a certain amount of the sample is taken out with a microsyringe or an injection device using a needle and the like, and an injection port plug ( The needle is pierced into the septum rubber), and the needle is injected with the tip of the needle positioned in the sample vaporization chamber. In a gas chromatograph using a capillary column, a carrier gas and a sample are mixed at a fixed ratio in a sample vaporization chamber, a part is introduced into the capillary column, and the other is discharged. There is a splitless mode in which the sample is injected and mixed while the inflow amount of the carrier gas is reduced, and the entire amount is introduced into the capillary column.

[Problems to be solved by the invention]

The analysis accuracy of a gas chromatograph using a capillary column depends on how uniformly the sample components are vaporized and introduced into the column in a sample vaporization chamber (usually in a glass insert). Further, the introduction accuracy is affected by the length (distance) between the tip of the syringe needle and the column inlet, and the optimum length (distance) changes when the injection amount of the sample changes. However, in the conventional sample introduction device, the position of the needle at the time of sample injection is fixed so as to always be at a fixed position, and the optimum length (distance) is selected according to a change in the injection amount to change the position of the needle. Has not become. Therefore, the analysis accuracy may vary depending on the sample amount and the injection position of the needle. The present invention has been made to solve such a problem.

[Means for solving the problem]

That is, in a gas chromatograph automatic sample injection device for injecting a fixed amount of a sample into a syringe fixed to a syringe support from a needle into a sample vaporization unit, the syringe support is attached to a vertically movable movable device, Positioning means is provided in which a distance between a needle tip of the syringe and an inlet end of a capillary column in the sample vaporizing section is set to an optimum position according to a sample injection amount.

[Action]

First, for many types of samples, the relationship between the optimal distance between the inlet of the capillary column and the tip of the needle and the analysis sample is determined in advance by using positioning means.

When analyzing a certain sample, the optimum position between the tip of the needle and the entrance of the capillary column is known in advance, so that it is set to that distance by the positioning means. Thus, when the syringe support is lowered to reach the set distance, the syringe support stops. In this case, the needle penetrates the septum of the sample vaporizing section, but the distance between the needle tip of the syringe and the entrance of the capillary column automatically becomes the optimum distance of the sample. If the plunger of the syringe is automatically pushed when the positioning means stops, the sample can be automatically injected into the sample vaporizing section at an optimum distance, mixed with the carrier gas, and introduced into the capillary column.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view of a main part of a sample injection device for a gas chromatograph according to the present invention. Reference numeral 1 denotes a syringe for injecting a sample, which is fixed and held on a syringe support 4 by a fixture 5. The head of the plunger 2 inserted into the syringe 1 is fixed to a driving device 6 so that a sample obtained by vertically moving the plunger is injected from the needle 3. As the driving device 6, other devices that can be driven up and down, such as a stepping motor, an air cylinder, a pinion and a rack, can be used.

Next, the syringe support 4 is moved up and down along the guide bar 7 by a vertical moving device. That is, a combination of a pulley 9 driven by a stepping motor 8 and a tamping belt 10 is used as the vertical moving device, and the arm 4a of the syringe support 4 is attached to the tamping belt 10.
Is fixed. In addition, as a device for vertically moving the syringe support 4, other combinations of a chain and a sprocket,
A method using a combination of a pinion and a rack may be used. In this way, the syringe support 4 is moved by the vertical moving device, and the needle 3 attached to the end of the syringe 1 is moved to the sample vaporizing section 24.
The needle tip 3a penetrates through the septum rubber 25 so that the needle tip 3a is located in the glass insert 26.

Reference numeral 11 denotes a movable stopper which moves on the table 12 in the horizontal direction, and a long groove 11a is penetrated therethrough in the moving direction of the central portion.
The guide rod 7 is inserted through 1a. As shown in FIG. 2, the movable stopper 11 is formed in an uneven shape so that the upper portion has three levels, and a shaft 13 serving as a worm gear is fixed to an end. And the shaft 13 of the worm gear is
The movable stopper 11 is moved in a horizontal direction by meshing with a pinion 15 driven by a motor 14. However, fixed stoppers 16 and 17 are fixed on the base 12 to stop the movable stopper 11 at a predetermined position, and a stopper 18 projects inside the base 12 so as to stop the movable stopper 11 halfway. A switch 19 is provided. Switches 20 and 21 are attached to the front and rear ends of the movable stopper 11 so as to stop the motor 14 when the fixed stopper is brought into contact with the stopper.

Further, a collar 22 is fixed to the arm 4a of the syringe support 4, and the arm 4a
The collar 22 is contacted via the collar 22 so as not to contact the upper surface. A switch 23 is attached to the lower end surface of the collar 22 so as to stop the stepping motor 8 when it comes into contact with the upper surface of the movable stopper 11.

Next, a method (operation) of positioning the needle tip 3a of the syringe 1 at the optimum position will be described.

First, when the collar 22 fixed to the arm 4a abuts on the upper surface of the movable stopper for many types of samples, the optimal distances L ₁ and L ₁ between the inlet 27a of the capillary column 27 and the tip 3a of the needle 3 are set. _2. Investigate the relationship between ……… and the analysis sample in advance.

When analyzing certain samples, its position distance L ₁ is at best the needle distal end portion 3a and the capillary column inlet 27a is a collar 22 on the upper surface of the stage 11b of the mobile stopper 11 is when in contact.

Then, the motor 14 is driven to drive the pinion 15 and the worm gear 13.
When the movable stopper 11 is moved rightward as shown in FIG.
The motor 14 is stopped when the switch 17 is touched by contacting the switch 17, and the movable stopper 11 is also stopped there.

Thus, the stepping motor 8 is driven to lower the arm 4a.
Upon contact with 11b, the stepping motor 8 stops. In this case, the needle 3 penetrates the septum 25 of the sample vaporization unit 24, but the distance between the needle tip portion 3a and the capillary column inlet 27a is automatically become L _1. When the stepping motor 8 stops, the switch of the driving device 6 is automatically turned on and the plunger 2 is pressed, so that the sample is automatically and at an optimum distance in the sample vaporizing chamber 24 (glass insert 26).
Into the column and mix it with the carrier gas.
Can be introduced.

Similarly if the distance between the needle tip portion 3a and the capillary column inlet 27a and L _2, moves the mobile stopper 11 similarly to the position of the fixed stop 18 (although in this case, fixing stopper actuates the electromagnetic switch 19 It is preferable to lower the syringe support 4).

Although mobile stopper 11 in this embodiment has been described for the case of three-stage, may be increased number For further different numeric optimum distance L _n of other sample, the mobile stopper 11 of the various stages You may be able to exchange it for something. The mechanism for driving the movable stopper 11 may be a ball screw. Further, the positioning means is not limited to the movable type stopper which moves in the horizontal direction as in the present embodiment.
A plurality of stoppers that engage with the collar 22 are provided along the arrow, and the stopper that engages with the collar 22 is specified by inserting and removing the stopper with an electromagnet or air pressure, and the needle tip of the syringe 1 is stopped at a predetermined position. It is also possible.
It is convenient to drive these stoppers by inputting data of the amount of material to be injected into a central processing unit (CPU) in advance and automatically controlling each sample.

The sample injection device for a gas chromatograph according to the present invention further includes a PTV (rapid heating vaporization injection device) other than a vaporization chamber for a split / splitless mode or a cold on-column injection device using a 0.53 mm inner diameter column tube in a vaporization section. Can also be applied. When used in these, the sample is introduced into the glass insert column in a liquid state. Also in this case, it is needless to say that the needle can be adjusted to a position corresponding to the injection amount of the sample.

〔The invention's effect〕

The gas chromatograph sample injection device according to the present invention has a configuration as described in detail above. Therefore, when evaporating a sample liquid or introducing a sample, the position of the tip of the needle can be controlled and the optimum position can be adjusted according to the sample amount. Can be selected. Therefore, it is possible to improve the quantitative accuracy in the sample introduction analysis.

[Brief description of the drawings]

FIG. 1 is a perspective view of a main part of a sample injection device for a gas chromatograph according to the present invention, and FIG. 2 is a specific example diagram for stopping a syringe support at an optimum position. DESCRIPTION OF SYMBOLS 1 ... Syringe, 3 ... Needle, 4 ... Syringe support tool 6 ... Drive device, 7 ... Guide rod, 8 ... Motor 9 ... Pulley, 10 ... Timing belt 11 ... Moving stopper, 24 …… Sample vaporization section 27 …… Capillary column

Claims (1)

(57) [Claims] An automatic sample injector for a gas chromatograph for injecting a predetermined amount of a sample into a syringe fixed to a syringe holder through a needle into a sample vaporizer, wherein the syringe holder is moved vertically. Attach,
A gas chromatograph for a gas chromatograph, wherein a positioning means for setting a distance between a needle tip of the syringe and an inlet end of a capillary column in the sample vaporizing section to an optimum position according to a sample injection amount is provided. Automatic sample injection device.