JPS5918454A - Carrier gas controlling apparatus for on-column capillary chromatograph - Google Patents

Abstract

PURPOSE:To enhance the universality of the titled apparatus, by a method wherein a constant flow amount valve and a pressure regulating valve or a needle valve different in characteristics are combined and the selective use thereof is performed before and after specimen injecting operation. CONSTITUTION:At the begining of specimen injecting operation, a flowline change-over device 2 is rotated 90 deg. and a carrier gas is flowed through an equivalently adjusted variable register 7 to make the outlet pressure of a constant flow amount valve 1 unchangeable. The carrier gas passing a pressure regulating valve is flowed to the direction of a capillary column 4 through a specimen injecting apparatus 3. That is, when a needle is passed after a needle guide is pierced in order to pierce a syringe through thin septum rubber at the beginning of injecting operation, the carrier gas is leaked from the periphery of the needle and the inlet pressure of the capillary column is made almost equal to the atmospheric pressure. In the next step, this leakage is stopped and, when the indication of a pressure gauge 8 is raised to be made equal to the indication of a pressure gauge 5, the flowline change-over device 2 is returned to the original. Subsequently, the plunger of the syringe is pushed to put a specimen on a place in the vicinity of the inlet of the capillary column 4 and retracted to pull out the needle from the septum rubber. Thereby, measurement is performed smoothly.

Description

Detailed Description of the Invention (1) Description of the technical field to which the invention pertains The present invention relates to a device for controlling the flow of carrier gas in an on-column capillary gas chromatograph. It involves a carrier gas control device that is designed to correspond to the chromatography and to have a constant flow function during chromatographic measurements.

(2) Description of the prior art Regarding the sample injection method in an on-column capillary gas chromatograph, see the document rlJ (HRC&CCH
1978) 263) or literature r2J (HRC&C
The method described in C. Sat (1981) 295) is widely known. When we replicated the methods described in these publications, we found that in both cases, at the time of depressing the syringe plunger, the carrier gas leaked out from around the needle into the atmosphere quite significantly, requiring simple control of the carrier gas. It was found that when a flow valve is used, the flow rate of carrier gas in the capillary column is significantly reduced and is close to zero. As a result, when injecting a sample under such conditions,
It was found that the sample circulates between the needle and the inner wall of the capillary column by capillary action, thereby contaminating the outside of the υ needle with sample and contaminating the exit path of the needle. As another method, the present inventor has developed a sample injection method (patent application filed in 1983) that solves this inconvenience.
-213230 Specification: %1) was devised. In this method, when the needle enters the capillary column, the carrier gas pressure at the inlet of the capillary column becomes approximately normal pressure at one point, and then by eliminating gas leakage from around the needle, the column inlet pressure It is characterized by returning the pressure to the pressure before needle entry and then injecting the sample. In this method, as mentioned above, there is a process in which the outlet pressure of the constant flow valve that controls the flow rate of the carrier gas returns from zero to the pressure before the needle enters. Since this process usually takes 90 seconds or more, there has been a desire to develop a method to speed up the process.

One such method has already been proposed by the present inventor and is described in Japanese Patent Application No. 57-31155 filed by the same applicant as the present applicant.

(3) Detailed Description of the Invention The present invention, unlike the invention described in the above specification, provides a highly versatile control device designed to be applicable to sample injection methods such as the on-column capillary method. That is the purpose of this.

(4) Detailed Description of the Invention The apparatus of the present invention combines a constant flow valve with different characteristics with a pressure regulating valve or a needle valve, and selects and uses these valves as appropriate before and after the sample injection operation to inject the sample into the capillary column. The inlet pressure of the capillary column is made approximately equal to the population pressure before the sample injection operation, and a carrier gas is caused to flow through a constant flow valve during chromatographic measurements.

More specifically, in the device according to the present invention,
When there is a change in the column inlet pressure due to the sample injection operation, the increase in pressure is less than that of a constant flow valve. Once the desired flow rate is approximately reached at the column temperature of the column, the sample is injected, the needle is removed from the sample injector, and the carrier gas is routed through the constant flow valve whose outlet is already at that pressure. After that, the constant flow rate is controlled by the constant flow valve, or once the column inlet pressure reaches the desired pressure, the carrier gas is supplied to the sample injection device by the constant flow valve, and then It is designed to inject the sample and then pull out the syringe needle.

The device of the present invention requires a constant flow valve, a flow path switch, a connection pipe to a sample injection device, a variable resistor, a pressure regulating valve, or a needle pulp. A pressure needle is attached to make it easier to adjust the device.

The flow path switching device here does not necessarily have to be one cock, but may have the function of switching the flow path by a combination of two or more cocks. Then, by arranging them, the flow path of the carrier gas is determined by (1) passing through a constant flow valve and a flow path switching device to the sample injection device, or cutting off the flow path to it using a flow path switching device; The present invention includes a flow path that can pass through a variable resistor and (2) a flow path that can lead to a sample injection device via a constant pressure valve or a needle valve.

The method of operating this device varies greatly depending on the sample injection device connected to it. I have already devised a typical example (%
(Japanese Patent Application No. 56-213230) A case in which it is combined with a sample injection device will be described. First, ■, Start the sample injection operation. Before the carrier gas leaks from around the injection needle and the outlet pressure of the constant flow valve decreases, the flow of carrier gas must be reduced from the sample injection device to below the sample injection port. The outlet pressure of the constant flow valve is maintained unchanged by changing the flow path resistance to be adjusted to be equivalent to the flow path of . Subsequently, (1) connect the flow of carrier gas that has passed through the pressure regulating valve or needle pulp to the sample injection port, and (2) begin the sample injection operation as already described (Japanese Patent Application No. 56-213230).

■Return the column inlet pressure to the pressure before starting the sample injection operation.

(2) Connect the flow of carrier gas that has passed through the constant flow valve to the sample inlet, and at the same time remove the flow from the pressure regulating valve or needle valve. (2) Push the plunger of the syringe.

It consists of each of the above steps.

The structure of the sample injection port does not limit the application of the present invention. That is, the present invention is based on the aforementioned patent application filed in 1973.
The present invention can be used not only in a sample injection device having a structure suitable for the sample injection method described in No. 6-213230, but also in combination with the known injection devices of the above-mentioned documents “1” and “2”. This is possible as shown in the examples.

(5) Detailed Description of the Invention Next, the present invention will be specifically described by way of preferred embodiments and with reference to the drawings so that the content of the present invention can be easily understood.

Example 1 Figure 1 shows a first example of a rapid steady-state constant flow device (left side of the dotted line in the figure) based on the present invention, which injects a sample without carrier gas leaking around the syringe needle. A sample injection device devised to enable
230 (to the right of the dotted line in the figure), and shows the state before starting the sample injection operation.

In the illustration, the carrier gas passes through a constant flow valve 1, enters a sample injection device 3 via a flow path switch 2, and flows through a capillary column 4 in the direction of the detector. The inlet pressure of the capillary column 4 at that time is indicated by the pressure gauge 5. The other carrier gas passes through a pressure regulating valve 6, a flow path switching device 2, a variable resistor 7, and is discharged into the atmosphere. The inlet pressure of the variable resistor 7 at that time is indicated by the pressure gauge 8. Prior to the sample injection operation, the flow path switching device 2 is rotated 90 degrees to direct the carrier gas that has passed through the constant flow valve 1 to the variable resistor 7 via the flow path switching valve 2. 5 so as not to change before and after the operation of the flow path switching device 2.

As a result, the resistance of the variable resistor 7 is equivalent to the resistance of the flow path below the sample injection device 3. Next, switch the flow path switch 2 to the first
In the state shown in the figure, adjust the pressure regulating valve 6 so that the indication on the pressure gauge 8 becomes the same as that on the pressure gauge 5. In this way, preparations before starting the sample injection operation are completed.

To start the sample injection operation, first, the flow path switching device 2 is rotated 90 degrees from the state shown in FIG. In this way, the outlet pressure of the constant flow valve 1 is kept unchanged. The carrier gas that has passed through the pressure regulating valve 6 is transferred to the sample injection device 3.
through the capillary column 4. The specific sample injection operation has already been described (Japanese patent application 1983-
No. 213230 Specification 11) According to the method. That is, in order to pierce the septum rubber with the thin needle of the syringe at the beginning of the injection operation, the needle guide is passed through it and then the syringe needle is passed through it. At this stage, the carrier gas leaks around the needle and the inlet pressure of the capillary column is almost atmospheric. Next, when the leakage around the needle is stopped, the reading on the pressure gauge 8 quickly rises and becomes equal to the reading on the pressure gauge 5. When the two directions become equal, the flow path switch 2
Return it to its original state as shown in Figure 1. At this time pressure gauge 5
The instructions hardly work. Press the plunger of the syringe and place the sample near the inlet of the capillary column 40.
Retract and remove the needle from the septum rubber. This completes the injection operation.

As described above, when the apparatus of the present invention is used, a drop in column inlet pressure during a period of sample injection operation can be quickly recovered by using the pressure regulating valve 6, and the sample is placed on the column and chromatographic measurement begins. Sometimes, the constant flow valve 1 is used, which has the advantage that subsequent measurements can be carried out smoothly.

In the above, before pressing the plunger, the carrier gas flowing into the capillary column is switched from passing through the pressure regulating valve 6 to passing through the constant flow valve 1, but this switching can also be done after pushing the plunger. do not have. Further, the present device can be used in the same manner even if the pressure regulating valve 6 is replaced with needle pulp.

Embodiment 2 FIG. 2 shows an embodiment of the present invention @2, in which the rapid steady-state constant flow device (left side of the dotted line in the figure) based on the present invention was replaced with a known on-column sample injection device (HRC&CC1 (1978)).
The figure shows the state before starting the sample injection operation.

The carrier gas flows through the constant flow i-valve 1, through the flow path switching device 9, through the sample injection device f10, and through the capillary column 4 toward the detector. The other carrier gas passes through the needle pulp 11 and the strafuhal 7'12f and joins the flow path of the key carrier gas, but in the illustrated state, the stop pulp 12 is closed. Prior to injecting the sample, the variable resistor 7 is adjusted in the same manner as shown in Example 1, and the magnitude of the resistance is determined by the sample injection device 10.
Let it be equivalent to the flow path resistance below. The procedure for sample injection is as follows.

The flow path changer 9 is turned counterclockwise by 90 degrees as shown, and the carrier gas that has passed through the constant flow valve 1 is made to flow through the equivalently adjusted variable resistor 7, and the stop pulp 12 is opened. Next, open the three-way cock 13 attached to the sample injection device @10, insert the long thin needle attached to the syringe into the capillary column, open the needle pulp 11, and press the pressure gauge 8.
No other pressure! Flow the carrier gas so that the ratio is close to 1'5. The plunger of the syringe is pressed, the needle is retracted, the stopcock 13 is closed, and the stopcock 12 is quickly closed to bring the flow path switching device 9 into the state shown in FIG.

When the device of the present invention is used, a portion of the carrier gas that has passed through the needle pulp 11 leaks from around the injection needle during the sample injection operation, but since the inlet pressure of the capillary column is close to the pressure indicated by the pressure gauge 5, the gear pillar Carano,
The carrier gas flows sufficiently inside the capillary, greatly reducing the inconvenience that the sample pushed out by the plunger becomes a plug in the capillary column and wraps around the needle and the inner wall of the capillary column due to capillary action, contaminating the outside of the needle. . At the start of chromatographic measurements, the carrier gas entering the sample injection device 10 is switched to the carrier gas that has passed through the constant flow valve 1 using the flow path switch 2, which has the advantage that subsequent measurements can be carried out smoothly. Of course, even if the needle pulp 11 is replaced with a pressure regulating valve, it can be operated and used in the same manner.

As described above, the device ≧ based on the present invention can be widely applied regardless of the sample injection device.

Embodiment 3 The 31st word indicates the third embodiment of the present invention, and the known (:E
The device of the present invention is attached from both sides j to the sample injection device f14 (the part between the two dotted lines in the figure), which is similar to that of IRCt & CC et al. (1981,) 295). The situation is shown before starting the injection operation.

The carrier gas passes through the constant flow valve 1, enters the sample injection device 14 via the three-way cock 15, and part of it passes through it, passes through the three-way cock 16, passes through the needle pulp 17, and enters the atmosphere at a rate of O~10 m1/min. the other flows through the capillary column 4 for 2 to 6 m, about 4/min towards the detector. = A'Yabira IJ - The inlet pressure of the column is indicated by the pressure gauge 5. The other gear gas flow path passes through a pressure regulating valve 6 and is stopped at a three-way cock 16.

Prior to sample injection, the resistance of the oJ variable resistor 7 is adjusted in the same manner as in Example 1 so that the resistance is equivalent to that of the sample injection device yt14 or lower. That is, the three-way cock 15 is closed, the other three-way cock 18 is opened, and the variable resistor 7 is adjusted so that the reading on the pressure gauge 5 is the same value as before starting this operation. In this embodiment, the three-way cock (15, 1
8) is used in combination as a flow path switching device.

Next, the three-way cock 16 is rotated 90 degrees clockwise as shown, and a separately prepared needle guide is inserted into the septum rubber of the sample injection device i14. The carrier gas that has passed through the pressure regulating valve 6 enters the sample injection device 14 via the three-way cock 16, and a portion leaks into the atmosphere from its needle guide. The pressure regulating valve 6 is adjusted so that the reading on the pressure gauge 8 is almost the same as that on the pressure gauge 5. By doing this, the carrier gas is flowing into the capillary column 4 as well as before the injection operation.

In this state, the sample is injected into the capillary column 4, the injection needle and needle guide are removed from the septum rubber, and the three-way cock 16 is quickly rotated 90 degrees counterclockwise to open the three-way cock 15 and close the other three-way cock 18. Set it to the state shown in . In this way, chromatographic measurements are performed using the carrier gas that has passed through the constant flow valve 1. At this point, a part of the carrier gas passes through the sample injection bag @14 and leaks into the atmosphere from the three-way cock 16 through the needle valve 17. This is to remove internal contamination.

(6) Effects of the Invention As described above, the apparatus of the present invention utilizes the quick pressure adjustment function of the pressure regulating valve or needle valve at certain points during sample injection operation, and at the time of chromatographic measurement.
According to the present invention, since the outlet pressure is switched to a constant flow valve in which a constant flow is flowing at a predetermined pressure, and the constant flow lid function can be utilized thereafter, the column input during one period of the sample injection operation can be reduced. A pressure drop can be quickly recovered by using a pressure regulating valve, and when a sample is loaded onto a column and chromatographic measurements are started, a constant flow valve is used to ensure smooth subsequent measurements. This method has the advantage of being highly versatile as it can also be applied to sample injection methods.

[Brief explanation of the drawing]

1, 2 and 3 show an apparatus according to the invention for explaining first, second and third embodiments of the invention, respectively. 1... Constant flow valve, 2.9... Flow path switch, 3.10
．． 14...Sample injection device, 4...Capillary column, 5.8Φ...Pressure tl', 6---111 pressure valve, 7
...Variable resistor, 11.17・Standard tube needle valve,
12.13.15.18... Three-way cock, 16. Urn.
Mikata Cook Special Fraud Applicant Yuji Takayama Patent Attorney Yutabe Kumagaya No. 31

Claims (1)

[Claims] By switching between the first flow path through which the carrier gas flows through the constant flow valve, the flow path switching device, and the sample injection device, and the tenth flow path being cut off by switching the flow path switching device, the carrier gas flows through the constant flow path into the sample injection device. A second flow path through which the carrier gas flows to the variable resistor via a flow rate valve and a flow path switch; and when the carrier gas does not flow to the sample injection device through the @1 flow path, the sample flows through a constant pressure valve or a needle valve. 1. A carrier gas control device for an on-column capillary chromatograph, comprising: a third channel through which a carrier gas can flow through an injection device.