JP3834902B2 - Sample introduction method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sample introduction method for introducing a sample into an analyzer such as a liquid chromatograph, and more particularly to a sample introduction method suitable for use when performing an automatic analysis using an autosampler.
[0002]
[Prior art]
As a sample introduction device, a sample measurement sampling loop having a sample introduction needle at the tip is used, the needle is inserted into a sample bottle, the sample is sucked into the sampling loop using a syringe, and the needle is measured. An apparatus is used that is connected to a sample introduction port of a liquid chromatograph and switches the flow path so that the mobile phase flows from the needle to the column through the sampling loop to introduce the sample.
[0003]
After the sample is introduced, the needle is moved to the washing pot to prevent cross-contamination, and the outside is washed with the washing liquid, and the washing liquid is flowed from the sampling loop to the needle using the syringe used to suck the sample. As a result, the inside of the sample introduction channel is also washed.
Sample weighing at the time of sample introduction and supply of cleaning liquid at the time of cleaning are performed using a common syringe.
[0004]
[Problems to be solved by the invention]
Since sample introduction is performed using a syringe, a common syringe is used regardless of whether the amount of sample injected during analysis is very small or large. As a result, it is difficult to accurately measure the sample injection amount from a small amount to a large amount.
An object of the present invention is to provide a sample introduction method capable of accurately measuring both a small amount and a large amount of sample.
[0005]
[Means for Solving the Problems]
The sample introduction device used in the sample introduction method of the present invention includes a sample metering sampling loop having a sample injection needle at the tip, a metering pump, a port connected to the sampling loop, and a port connected to a flow path for supplying a mobile phase. At least a port connected to the column, a port connected to the sample introduction port, and a port connected to the multi-position valve connected to the metering pump, and a flow path for the mobile phase to flow from the sample introduction port to the column through the sampling loop and the needle is formed. A multi-port valve that switches between an injection state and a load state in which the mobile phase forms a flow path to the column without passing through any of the sampling loop, needle, and sample inlet, and the metering pump is connected to a common port. The common port at least Port leading to the switch-port valve, and a said multi-position valve which connects switching between ports connected to a port and cleaning the pot leads to the washing liquid. A metering pump having a capacity smaller than that of the sampling loop is used.
[0006]
At the time of sample introduction, the multi-port valve is loaded, and the needle is connected to the metering pump via the sampling loop by the multi-position valve. After the needle is immersed in the sample and the required amount of sample is drawn by the metering pump, the needle moves to the sample inlet, the multiport valve is switched to the injection state, and the sample is introduced into the column by the mobile phase. The
[0007]
If the amount of sample introduced exceeds the capacity of a single stroke of the metering pump, a predetermined large amount of sample is aspirated by switching the multi-position valve and repeating the metering pump while the multiport valve is still loaded. After that, the needle moves to the sample inlet, the multiport valve is switched to the injection state, and the sample is introduced into the column by the mobile phase.
[0010]
【Example】
FIG. 1 shows a flow chart of an example of a sample introduction apparatus to which one embodiment is applied. A sampling loop 4 for sample measurement is connected to the port 2 a of the 6-port valve 2, and a sample injection needle 6 is provided at the tip of the sampling loop 4. The port 2b of the 6-port valve 2 is connected to a mobile phase supply channel 12 through which the mobile phase 8 is supplied by the liquid feed pump 10, the column 14 is connected to the port 2c, and the sample is connected to the port 2d. An inlet 16 is connected, and the ports 20d and 20e of the 6-position valve 20 are connected to the ports 2e and 2f.
[0011]
Reference numeral 20 denotes a 6-position valve that can be connected to the common port 20a by switching to six positions. The suction / discharge port of the plunger pump 22 is connected to the common port 20a. The plunger pump 22 also has a suction port, which is connected to the port 20 b of the 6-position valve 20. A flow path connected to the cleaning liquid 24 is connected to the port 20c of the 6-position valve 20, and ports 2e and 2f of the 6-port valve 2 are connected to the port 20d and the port 20e, respectively. The port 20f is connected to the cleaning pot 26. It is connected to the flow path. The 6-position valve 20 is configured to connect the common port 20a to any one of the ports and switch the connection between ports other than the common port.
In the vicinity of the 6-position valve 20, a vial 28 containing a sample is disposed.
[0012]
The needle 6 can move between the positions of the sample inlet 16, the washing pot 26 and the vial 28, and the sample inlet 16 is provided with a seal member so that the needle 6 is liquid-tight and the sample inlet 16 is maintained. So that a closed flow path can be formed.
[0013]
Next, referring to FIG. 2, the operation in which the sample is sucked into the sampling loop 4 and introduced into the liquid chromatograph will be described. 2A to 2C show a case where the sample introduction amount is equal to or less than the capacity of one stroke of the plunger pump 22.
(A) As shown in FIG. 2 (A), the 6-port valve 2 is set to the load state, and the sampling loop 4, the needle 6 and the plunger pump 22 are connected to the ports connected to the washing pot 26, The flow path is opened to atmospheric pressure.
[0014]
(B) When the 6-position valve 20 is rotated 60 ° rightward in the drawing, the needle 6 is connected to the plunger pump 22 via the sampling loop 4. Next, the needle 6 is separated from the sample inlet 16 and immersed in the sample in the vial 28. Thereafter, the plunger of the plunger pump 22 is retracted and the sample in the vial 28 is inhaled by a necessary amount.
[0015]
(C) The needle 6 moves to the sample inlet 16 and is fitted into the sample inlet 16, the 6-port valve 2 is switched to the injection state, and the 6-position valve 20 is further rotated 60 ° to the right in the figure. . In this state, the mobile phase 8 is supplied by the liquid feed pump 10, and the sucked sample is introduced from the needle 6 through the sample inlet 16 into the column 14.
During that time, the plunger of the plunger pump 22 returns to the origin, and the cleaning liquid in the flow path of the plunger pump 22 is discharged to the cleaning pot 26.
[0016]
On the other hand, when the amount of sample introduced exceeds a capacity of one stroke of the plunger pump 22, the 6-port valve 2 is in that state after the sample is sucked by the plunger pump 22 in FIG. In this state, the 6-position valve 20 is switched to the position shown in FIG. 2C, the plunger pump 22 is returned to the origin, and the position is switched again to the position shown in FIG. Thus, by repeating the sample inhalation by the plunger pump 22, a large amount of sample exceeding the capacity of one stroke of the plunger pump 22 is inhaled. Thereafter, the 6-port valve 2 and the 6-position valve 20 are switched to the state shown in FIG. 2C, and the sucked sample is introduced into the column 14.
[0017]
The operation for cleaning the needle and the flow path for sample injection will be described.
(When cleaning the sample injection channel and the inside and outside of the needle)
(A) After the sample is introduced into the column 14, as shown in FIG. 3 (A), the 6-position valve 20 is switched to the position where the ports 20b and 20c are connected, and the intake port of the plunger pump 22 is dedicated. Is connected to the flow path of the cleaning liquid 24. Then, when the plunger of the plunger pump 22 is retracted, the cleaning liquid 24 is sucked into the plunger pump 22.
[0018]
(B) Thereafter, after the 6-position valve 20 is rotated 180 degrees to the left in the figure, the plunger of the plunger pump 22 is advanced to discharge the cleaning liquid, and the plunger pump 22 and the 6-port valve 2 are connected. The flow path is washed.
By repeating the steps of FIGS. 3A and 3B, the flow path connecting the plunger pump 22 and the 6-port valve 2 is cleaned with a sufficient amount of cleaning liquid.
[0019]
(C) When cleaning the needle and the channel for sample injection, as shown in FIG. 3C, the 6-position valve 20 is rotated 180 degrees to the right in FIG. The suction port of the plunger pump 22 is connected to the flow path of the cleaning liquid 24, the 6-port valve 2 is switched to the load state, and the needle 6 is placed in the cleaning pot 26. Then, after the plunger 24 is retracted, the cleaning liquid 24 is sucked into the plunger pump 22, and then the 6-position valve 20 is rotated 120 degrees in the left direction in FIG. When the plunger 22 is advanced, the cleaning liquid is discharged from the sampling loop 4 through the inside of the needle 6 to the cleaning pot 26, and the inside of the sample injection channel and the inside and outside of the needle 6 are cleaned.
[0020]
In FIG. 3 (C), the 6-position valve 20 is switched between the position indicated by the solid line and the position indicated by the broken line, and is repeatedly washed, so that the inside of the flow path for sample injection and the inside and outside of the needle 6 are changed. It can be washed with a sufficient amount of washing liquid.
[0021]
(For cleaning by simply immersing the needle in the cleaning pot)
From the state of FIG. 2A, the 6-position valve 20 is switched to the position of FIG. 2B, and the needle 6 is immersed in the cleaning pot 26.
[0022]
(When washing the outside of the needle by pouring the washing liquid into the washing pot with the needle immersed in the washing pot)
From the state shown in FIG. 2A, the 6-position valve 20 is switched to the position shown by the solid line in FIG. 3C, and the needle 6 is immersed in the washing pot 26. After the cleaning liquid 24 is sucked into the plunger pump 22, the 6-position valve 20 is rotated 60 ° counterclockwise in FIG. 3C to connect the plunger pump 22 to the cleaning pot 26 and suck into the plunger pump 22. The cleaned cleaning liquid is sent to the cleaning pot 26 and the outside of the needle 6 is cleaned.
When repeating this cleaning operation, the 6-position valve 20 is switched to the position shown by the solid line in FIG. 3C again, and after the cleaning liquid 24 is drawn into the plunger pump 22, the plunger pump 22 is connected to the cleaning pot 26. Thus, the 6-position valve 20 is rotated, and the cleaning liquid is sent from the plunger pump 22 to the cleaning pot 26. This operation is repeated as many times as necessary.
As described above, the needle and the sample injection channel can be cleaned sufficiently with a large amount of cleaning liquid by switching the multi-position valve and repeating the operation of the metering pump so that cross contamination can be effectively suppressed. .
[0023]
FIG. 4 shows the operation when the sample is diluted with the cleaning liquid. With the needle 6 immersed in the vial 28, the 6-position valve 20 is moved to the solid line position, the cleaning liquid 24 is sucked into the plunger pump 22, and the 6-position valve 20 is switched to the broken line flow path from the plunger pump 22. By sending out the washing liquid, the washing liquid is injected from the needle 6 into the vial 28, and the sample is diluted.
[0024]
【The invention's effect】
In the present invention, the sample is metered using a metering pump and a multi-position valve. When a large amount of sample is introduced, a large amount of sample can be sucked into the sampling loop by switching the multi-position valve and repeating the metering pump. Therefore, it becomes possible to accurately measure from a small amount of sample to a large amount of sample.
[Brief description of the drawings]
FIG. 1 is a flow chart showing an example of a sample introduction apparatus to which one embodiment is applied.
FIG. 2 is a flow chart showing a sample introduction method of one embodiment.
FIG. 3 is a flow path diagram showing a cleaning operation by the sample introduction device.
FIG. 4 is a flow path diagram showing a dilution operation by the sample introduction device.
[Explanation of symbols]
2 6-port valve 2a to 2f 6-port valve port 4 Sampling loop 6 Needle 12 Mobile phase supply flow path 14 Column 20 6-position valve 20a 6-position valve common port 20a to 20f 6-position valve port 22 Plunger pump 24 Cleaning fluid 26 Washing pots 28 vials

Claims (1)

A sampling loop for sample weighing with a needle for sample injection at the tip;
A metering pump;
At least a port connected to the sampling loop for sample measurement, a port connected to a flow path for supplying a mobile phase, a port connected to a column, a port connected to a sample introduction port, and a port connected to a multi-position valve described later after connecting the measurement pump; An injection state in which the mobile phase forms a flow path that flows from the sample inlet to the column through the sampling loop and needle, and a flow path that flows to the column without the mobile phase passing through the sampling loop, the needle, and the sample inlet. A multi-port valve that switches between load states;
A sample introduction apparatus comprising: a multi-position valve, wherein the metering pump is connected to a common port, and the common port is switched between at least a port connected to the multi-port valve, a port connected to a cleaning solution, and a port connected to a cleaning pot. In the sample introduction method using
Use a metering pump with a smaller capacity than the sampling loop,
When the sample introduction amount to be injected is equal to or less than the suction capacity of one stroke of the metering pump, when the multi-port valve is in a load state, the metering pump performs one suction to the sampling loop,
When the sample introduction amount to be injected is larger than the suction capacity of the metering pump in one stroke, when the multiport valve is in a load state, the metering pump is connected to the sampling loop through the switching of the multiposition valve. A sample introduction method, wherein suction is performed twice or more.

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