JPH0416762A - Sample introducing apparatus for supercritical liquid chromatography - Google Patents

Abstract

PURPOSE:To prevent the fluctuation of the introducing amount of a sample due to the clogging of a resistance pipe by introducing the sample into a buffer container held to final analytical pressure and dissolving the sample in a mobile phase to dilute the same to discharge the diluted sample to a separation column. CONSTITUTION:A sample is injected in a sampling valve 1 from the sample injection port 4 thereof and, at the same time, a mobile phase is supplied to a buffer container 3 from a mobile phase feed part 2. This mobile phase is injected in the container 3 in a supercritical state and a part thereof is discharged to the atmosphere through a resistance pipe 8 to hold the interior of the container 3 to final analytical pressure. After the sample is injected, when the valve 1 is revolved to connect a sample injection pipe to the feed part 2 and container 3, the sample flows in a metering pipe 7. Subsequently, when a flow path change-over valve 6 is changed over, the mobile phase from a mobile phase feed part 9 flows in the metering pipe 7 and the sample is sent out to a capillary column 10 to be separated in a supercritical state. By this method, a predetermined amount of the sample can be introduced without generating the clogging due to the precipitation of a solute.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a sample introduction device suitable for supercritical fluid chromatography.

(Prior art) A supercritical chromatograph uses a gas fluid, such as carbon dioxide or ammonia, heated and compressed to a supercritical temperature and pressure as a mobile phase. The high solubility of a liquid makes it possible to dissolve polymeric substances at low temperatures, and the low viscosity of a gas makes it possible to use a capillary column as a separation column. It is used to analyze substances that are unstable or difficult to derivatize.

By the way, as mentioned above, when using a capillary column to obtain high separation performance, the sample load on the capillary column is extremely small, and it is difficult to inject a minute amount of sample with high precision, so it is difficult to maintain measurement accuracy. The practice is to inject as much sample as possible and introduce only a portion of this into the cathode column.

FIG. 2 shows an example of a sample introduction device used in the supercritical chromatograph described above, in which a resistance pipe is connected between the Sambrizig pulp A and the separation column B via a branch pipe C. The flow rate into the separation column B is adjusted by adjusting the fluid resistance of the resistance pipe.

In addition, the code|symbol E in the figure shows a mobile phase liquid feeding part.

(Problem to be solved by the invention) However, in a supercritical fluid chromatograph,
Since the sample is injected into the separation column under extremely high pressure, the solubility of the solvent is extremely high when it is present in the column, and the solubility decreases rapidly when it is discharged into the atmosphere.

For this reason, the solubility near the discharge end of the resistance tube rapidly decreases, and a phenomenon occurs in which components dissolved in the mobile phase precipitate and close the discharge end of the resistance tube. For this reason, the fluid resistance value of the resistance tube becomes larger than the set value, and the sample is not split, resulting in a large amount of flowing into the column.
As a result, there are problems in that the column load increases, resulting in a decrease in the fractional capacity and a decrease in reproducibility.

The present invention has been made in view of these problems, and its purpose is to eliminate the need for a split mechanism and to eliminate the need for a preset sample 1F! : The object of the present invention is to provide a new sample introduction amount W for supercritical liquid chromatography that can be reliably injected into a separation column.

(Means for Solving the Problems) In order to solve such problems, the present invention provides a mobile phase liquid feeding means, a sampling valve, a buffer container, and a resistance tube that communicates with the atmosphere at one end through a resistance tube that communicates with the atmosphere. A first flow path formed by connecting measuring tubes in series, and a second flow path connecting the measuring tubes to a mobile phase liquid feeding section and a separation column via a switching valve.

(Operation) The sample from the sampling valve is introduced into the buffer container maintained at the final analysis pressure in the separation column by a resistance tube, dissolved and diluted in the mobile phase, and then discharged into the separation column.

This eliminates the need for a resistance tube for adjusting the split ratio in the conventional apparatus, and therefore it is possible to prevent variations in the amount of sample introduced due to clogging of the resistance tube.

(Tora Embodiment) The details of the present invention will be explained below based on the illustrated Tora Embodiment.

Fig. 7 shows an embodiment of the present invention, in which reference numeral 1 is a subsibling valve, one end of which is connected to the mobile phase feeding section 2 that pressurizes the mobile phase fluid above supercritical pressure, and the other It is provided with a flow path connected to the buffer container 3 whose end is described, and two flow paths 1fr connected to the sample injection port 4 and the discharge port 5.

Reference numeral 3 denotes the aforementioned buffer container, which is configured to withstand supercritical pressure, and its discharge end is connected to a flow path switching valve 6, which will be described later.

Reference numeral 6 designates the aforementioned flow path switching valve, which connects the first flow path (the flow path indicated by the solid line in the figure) from the discharge end of the buffer container 3 through the metering pipe 7 to the resistance pipe 8 whose one end is open to the atmosphere. At one end of the metering tube 7, a two-layer mobile phase liquid feeding section 9 for pressurizing the mobile phase fluid above the supercritical pressure is connected, and at the other end, a capillary column 10 is connected, while a buffer device 3V! A second flow path (flow path indicated by a dotted line in the figure) which communicates with the atmosphere via the resistance tube 8 is switched. In addition, the symbol] 1 in the figure is
2 represents a detector connected to the discharge end of the Cadler column 10, and 2 represents a constant temperature bath.

In this embodiment, when a sample is injected through the sample injection port 4 of the sampling valve 1 with the flow path switching valve 6 set to the second flow path (the state shown by the dotted line in the figure), a portion of the sample enters the flow path. The excess amount is discharged to the outside from the discharge port 5.

At the same time, the mobile phase is supplied from the first mobile phase feeding section 2 to the buffer container 3 through the other channel of the sampling valve (the channel indicated by the solid line in the figure). As a result, the mobile phase from the first mobile phase liquid feeding section 2 is injected into the buffer container 3 in a supercritical state, and a part of it is released into the atmosphere via the resistance tube 8.
PA the inside of the buffer container 3 using the resistance tube 8! 121!
This should be maintained at final analysis pressure.

After injecting the sample, turn the sampling valve to connect the sample injection tube to the first mobile phase feeding section 2 and buffer container 3 (state shown by the solid line in the figure), the sample will be
The mobile phase from the mobile phase liquid feeding section 2 causes the buffer container 3
The 6x2a container 3 sent to
Since the internal pressure is set to be the pressure at the discharge end of the buffer, only the soluble components will be dissolved and the undissolved components will remain in the buffer container 3 until the end of the analysis. The mobile phase in the buffer container 3 in which the components have been dissolved roughly flows into the measuring tube 7.

Next, when the flow path switching valve 6 is switched to the second flow path (the flow path indicated by the dotted line in the figure), the mobile phase from the second mobile phase feeding section 9 flows into the metering tube 7, and the flow path of the metering tube 7 is A volumetrically defined amount of sample is delivered to the capillary column 10. By continuing to supply the mobile phase from the second mobile phase feeding section 9 in this state, separation is performed in a supercritical state within the capillary column 10, and the components are detected by the detector 11. Even if the pressure of the mobile phase decreases as it approaches the exhaust end of the column 10, only the components that can be dissolved at the final analysis pressure are dissolved in the buffer chamber 3 in advance.
This will prevent clogging that would otherwise occur due to the precipitation of solutes.

In this example, two mobile phase feeding sections are provided, but the same effect can be achieved even if the separation column and buffer container are commonly supplied from one mobile phase feeding section. is clear.

(Effects of the Invention) As explained above, in the present invention, a mobile phase liquid feeding means, a sampling valve, a buffer container, and a metering tube whose one end communicates with the atmosphere via a resistance tube that communicates with the atmosphere are connected in series. The first flow path is connected to the first flow path, and the second flow path connects the metering tube to the mobile phase feeding section and the separation column via the switching valve, so that the inside of the buffer container, which is previously maintained at the final analysis pressure, is provided. The sample can be diluted with the mobile phase and a stable amount of sample can be supplied to the separation column.

Furthermore, in the present invention, only the components that can be dissolved at the final analysis pressure are dissolved in the buffer container in advance.
Even if the pressure of the mobile phase decreases toward the discharge end of the separation column, the solute does not precipitate, thus enabling highly reliable analysis.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a loading device showing an embodiment of the present invention, and FIG. 2 is a block diagram showing an example of a sample introduction section of a conventional supercritical fluid chromatograph. 1...Sampling valve 2...Mobile phase liquid feeding section 3...Buffer container 6...Flow path switching valve 7...Measuring tube 8...Resistance tube 9
...Mobile phase feeding section 10...Separation column Fig. 1

Claims (1)

[Claims] Mobile phase feeding means, sampling valve, buffer container,
and a first flow path formed by connecting metering tubes in series, each of which is connected to the atmosphere through a resistance tube whose one end communicates with the atmosphere, and a switching valve that connects the metering tube to the mobile phase feeding section and the separation column. A sample introduction device for supercritical fluid chromatography comprising a second connecting channel.