JPH0436449Y2 - - Google Patents

Description

[Detailed description of the invention] (Technical field) The present invention relates to a sample introduction device for a liquid chromatograph, and particularly relates to a sample introduction device that can perform operations from analysis to fractionation and has a wide range of sample injection amounts. .

(Prior art) Liquid chromatography, especially high-performance liquid chromatography, has traditionally been used to develop and separate predetermined components in a sample introduced into a system in a separation column using a mobile phase solvent sent from a pump. Graphi (HPLC) has been widely adopted as a separation analysis method and preparative method. In a device for performing liquid chromatography, a so-called liquid chromatograph, a loop injector using a sample loop method is generally used to introduce a predetermined amount of sample into the system. It is used as a device.

By the way, such a loop injector includes a six-way valve as a flow path switching section provided on a flow path between a mobile phase pump and a separation column of a liquid chromatograph, and a sample injector through a sample injection port of the six-way valve. It consists of a sample loop section that holds a predetermined sample to be injected at the pump, and by switching the six-way valve, both ends of the sample loop are connected to the flow path on the mobile phase pump side and the separation column side. They are connected to each other so that the sample in the sample loop is guided to the separation column along with the mobile phase solvent discharged from the mobile phase pump, and by changing the capacity of the sample loop part, It is possible to inject samples of several tens of ml, and is known to have excellent performance in terms of operability and simplicity during injection.

(Problem) However, in liquid chromatographs for analysis, separation columns are generally used for samples up to several tens of microns in size, while for preparative separation, columns for samples up to several tens of microns in size are used. Since the separation column is used for samples up to 10 ml, the sample loop section for analysis inevitably holds a small amount of sample, and therefore a large amount of sample is used for preparative separation. When injecting a sample, it was necessary to replace it with a longer loop or a larger diameter in order to increase the amount of sample retained. However, there had not yet been a sample introduction device that could perform both analysis and fractionation in the same device.

As described above, when using a conventional loop injector for both analytical and preparative operations, it is necessary to replace the sample loop section, which is a very troublesome operation. It was.

In addition, in order to widen the sample area that can be injected, if a sample loop section with a large inner diameter with a capacity of several 100 ml is provided, several
When a small amount of sample, about 10 μm in size, is injected, diffusion tends to occur inside the sample loop, which causes the inherent problem that the number of theoretical plates decreases during separation using a separation column. On the other hand, if the sample loop section is constructed from a pipe with a narrow inner diameter of, for example, 0.5 mm, in order to prevent such diffusion, it is possible to achieve this purpose. To ensure a large sample loop capacity, the length of the pipe must be
The distance can exceed 100m, which is completely impractical.

(Solution Means) Here, the present invention was devised to solve the problems in the conventional loop injector type sample introduction device, and its feature is that the mobile phase of the liquid chromatograph is A flow path switching valve is disposed on the flow path between the pump and the separation column, and a sample loop is provided to hold a sample injected with a sample injector through the sample injection port of the flow path switching valve. By switching the switching valve, both ends of the sample loop are connected to the channels on the mobile phase pump side and the separation column side, respectively, and the sample in the sample loop is connected to the mobile phase discharged from the mobile phase pump. In the sample introduction device, the sample loop is configured with a pipe of different diameter, and a predetermined length portion of the sample loop on the side connected to the separation column side flow path, The pipe has a smaller diameter than the portion connected to the mobile phase pump side flow path.

(Function/Effect) Therefore, in a sample introduction device having such a configuration, since the sample loop that holds the injected sample is connected to pipes of different sizes (inner diameters), The amount of sample held in the large-diameter pipe section increases, and the sample injection amount range becomes wider without increasing the length of the pipe. There is no longer any need for extensive work or effort.

Moreover, the sample loop has a predetermined length on the side connected to the separation column side flow path, in other words, a predetermined length on the sample injection port side of the flow path switching valve into which a predetermined sample is injected by the sample injector. The length of the pipe is made up of small diameter pipes, so even if a small amount of sample, for example a few microns, is injected, such a small amount of sample will be retained in the small diameter sample loop. As a result, the diffusion phenomenon of the sample within the sample loop can be effectively suppressed or prevented, and this also eliminates problems such as a decrease in the number of theoretical plates during separation in the separation column. It could have been resolved advantageously.

(Example) Hereinafter, in order to clarify the present invention more specifically, one embodiment of the present invention will be described in detail based on the drawings.

First, FIG. 1 shows a system diagram of an example of a high performance liquid chromatograph (HPLC) as a liquid chromatograph equipped with a sample introduction device according to the present invention, in which 2 represents a predetermined mobile phase solvent. The mobile phase solvent in this storage tank 2 is guided through a flow path 6 to a known separation column 8 by the operation of a pump 4. Further, a sample introduction device 10 according to the present invention is provided on the flow path 6 between the pump 4 and the separation column 8, and a predetermined amount of sample introduced by the sample introduction device 10 is transferred to the pump 4. It is guided into a separation column 8 together with the mobile phase solvent sent from the sample, and within the separation column 8, each sample component is separated in a known manner and eluted together with the mobile phase.

Although not shown, a detector or the like for detecting the sample components separated and eluted by the separation column 8 is provided on the flow path downstream of the separation column 8, as necessary. ing.

By the way, the sample introduction device 10 includes a six-way valve 14 as a well-known flow path switching valve,
and a sample loop 16 attached thereto. More specifically, the six-way valve 1
4, as is well known, six ports whose flow paths are interrupted or interrupted by the rotation of the rotor 18, namely, a mobile phase inlet port 20a, a sample loop outlet port 20b, a drain port 20c, and a sample injection port 20d. , a sample loop inlet port 20e and a mobile phase outlet port 20f, of which the mobile phase inlet port 20a is connected to the flow path 6 on the pump 4 side, while the mobile phase outlet port 20f is connected to the separation column. The 6 portions of the flow path on the 8 side are connected. Furthermore, a predetermined sample is now being injected from the sample injection port 20d using a sample injector such as a syringe, and excess liquid is being discharged from the drain port 20c. .

A sample loop 16 for holding the sample to be injected is connected between the sample loop inlet port 20e and the sample loop outlet port 20b of the six-way valve 14. This sample loop 16 is composed of a first pipe 22 with a small diameter (inner diameter) and a second pipe 24 with a large diameter (inner diameter), and the first pipe 22 is connected to the sample loop inlet port 20e. while the second pipe 24
is connected to the sample loop outlet port 20b so that it can be connected to the flow path 6 portion on the pump 4 side.

Therefore, in the sample introduction device 10 having such a structure, when holding a predetermined sample in the sample loop 16, the second As shown in the figure, the sample loop inlet port 20e and the sample injection port 20d are
Further, the sample loop exit port 20b and the drain port 20c are connected to each other, and in this state, a predetermined amount of sample is injected from the sample injection port 20d using a predetermined sample injector such as a syringe. A predetermined sample is introduced into the first pipe 22 and further into the second pipe 24 of the sample loop 16. Note that the liquid present in the sample loop 16 is forced out of the sample loop 16 as the sample is injected, and the liquid present in the sample loop
b, and is further discharged to the outside of the system through the drain port 20c. Also,
During this sample injection, the mobile phase inlet port 20
a and the mobile phase outlet port 20f are connected, so that the mobile phase solvent constantly sent from the pump 4 is supplied to the separation column 8 through the channel 6.

And in this way, sample loop 16
After a predetermined amount of sample is injected and held in the
By rotating the rotor 18 of the six-way valve 14 by a predetermined angle (60°), as shown in FIG. The phase outlet ports 20f are connected to each other, so that the solvent sent from the pump 4 is connected to the sample loop 1.
The sample held in the column 6 is pushed out and guided into the separation column 8 through the channel 6, and a predetermined separation operation can be performed in the separation column 8 to separate the target sample components. will be carried out.

In this way, in the sample introduction device 10, a predetermined sample injected from the sample injection port 20d of the hexagonal valve 14 is first passed through the sample loop inlet port 20e to the first small diameter pipe of the sample loop 16. In the case of separation analysis operations targeting samples up to several tens of micrometers in size, it is necessary to keep such a small amount of sample in the first pipe 22. Then, depending on the diameter of the first pipe 22, the degree of diffusion of the sample can be effectively suppressed, thereby advantageously suppressing or preventing a decrease in the number of theoretical plates in the separation column 8. It can be done. From this, the first pipe 22
Regarding the size of the sample loop 16, the length and diameter should be appropriately determined to accommodate the amount of sample for purposes such as analysis where diffusion within the sample loop 16 is a problem. .

In addition, when a sample amount up to several tens of milliliters is targeted for the purpose of preparative separation, etc., when such a large amount of sample is injected, the inside of the first pipe 22 of the sample loop 16 After the sample is filled with the sample, the sample is introduced into the second pipe 24 which has a larger diameter (inner diameter), and a large amount of the sample can be held there. There is no need to make the length that long, and the desired amount of sample can be advantageously held. Note that this second pipe 2
The length and diameter of 4 will be determined as appropriate depending on the large amount of sample to be held.

Incidentally, in order to minimize the diffusion of the sample up to 10μ, a stainless steel pipe (first pipe 22) with an inner diameter of 0.25 mm and a stainless steel pipe (second pipe 24) with an inner diameter of 2.1 mm are connected. sample loop 16 (ensures a capacity of 360μ),
As a result of comparing sample loops made of stainless steel pipes with an inner diameter of 2.1 mm, it was found that the number of theoretical plates was
The number of theoretical plates was 7,100, whereas in the case of using sample loop 16, which is a combination of stainless steel pipes of different diameters, a theoretical plate number of 8,700 was obtained in the second case, and the reduction in sample diffusion contributed to the increase in the number of theoretical plates. It became clear that it was.

In addition, from this result, a sample loop 16 with a capacity of several tens of ml was constructed from pipes of different diameters.
It is possible to introduce a small amount of sample for analysis of a few microns without reducing the number of theoretical plates, and it is also possible to hold a large amount of sample, so there is no need to replace the sample loop. With one sample loop 16, it is possible to inject and hold samples ranging from several μ to several tens of ml.
There is no longer any need for the troublesome work or labor required to replace the sample loop according to the amount of sample as in the past.

Although one embodiment of the present invention has been described in detail above, it goes without saying that the present invention is not to be construed as being limited only to such illustrative specific example, and the present invention may deviate from its spirit. It should be understood that various changes, modifications, improvements, etc. can be made and implemented based on the knowledge of those skilled in the art.

For example, in the previous example, sample loop 16
is a first pipe 22 and a second pipe 2 of different diameters.
4, but it is also possible to construct a larger number of pipes with different internal diameters, thereby reducing the pipe length to a larger sample capacity range. It is possible to introduce the sample loop 16 without reducing the number of theoretical plates, and there is no problem in constructing the sample loop 16 with a pipe whose diameter (inner diameter) gradually changes. The smallest diameter portion of the pipe will be connected to the sample loop inlet port 20e of the six-way valve 14.

In addition, as a flow path switching valve represented by the six-way valve 14, in addition to the usual one having six ports, the sample injection port 20d is configured with a needle port provided in the rotor, and the syringe is inserted through this needle port. There is no problem even if it is a rheodyne type valve or the like that allows injection of a predetermined sample at a point.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing an example of a liquid chromatograph equipped with a sample introduction device according to the present invention.
FIG. 2 is an explanatory diagram showing one operating mode (sample injection state) of the sample introduction device. 2...Storage tank, 4...Pump, 6...Flow path, 8...
...Separation column, 10...Sample introduction device, 14...
Six-way valve, 16...Sample loop, 18...
Rotor, 20a...mobile phase inlet port, 20b
...Sample loop exit port, 20c...Drain port, 20d...Sample injection port, 20e
...Sample loop inlet port, 20f...Mobile phase outlet port, 22...First pipe, 24...
second pipe.

Claims (1)

[Scope of utility model registration request] A sample loop in which a flow path switching valve is disposed on a flow path between a mobile phase pump and a separation column of a liquid chromatograph, and holds a sample injected with a sample injector through a sample injection port of the flow path switching valve. By switching the flow path switching valve, both ends of the sample loop are connected to the flow paths on the mobile phase pump side and the separation column side, respectively, and the sample in the sample loop is transferred to the mobile phase pump. In the sample introduction device, the sample loop is configured with a pipe having a different diameter, and the sample loop is configured with a pipe having a different diameter, and the sample loop is connected to the separation column side flow path. A sample introduction device for a liquid chromatograph, characterized in that a predetermined length portion is a pipe having a smaller diameter than a portion connected to the mobile phase pump side channel.