JPH1038870A - Liquid chromatographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid chromatographic device small in base line fluctuation of chromatogram. SOLUTION: At least a part of a passage connecting the outlet side of a column 1 to the inlet side of a flow cell 2 is made double piping. A liquid sample flowing from the column 1 toward the flow cell 2 is made flow to the inner pipe side 10, and the liquid sample from the outlet of the flow cell 2 is made flow to the outer pipe side 12 so as to reduce liquid temperature fluctuation of an eluent flowing in the inner pipe, thereby reducing base line fluctuation of chromatogram depending on temperature fluctuation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid chromatograph, and more particularly, to a connection between a column and a flow cell in a liquid chromatograph.

[0002]

2. Description of the Related Art In a liquid chromatograph (hereinafter, a liquid chromatograph is referred to as an LC), a liquid sample separated by a column is sent into a flow cell by a mobile phase, and various detections including a UV detector are performed. It is configured such that a sample component passing through the flow cell can be detected by the instrument.

[0003] The flow cell of a UV detector for LC conventionally used has an inner diameter of 1 mm and a length of 10 mm.
A cylindrical shape of a degree is commonly used, and in this case, the cell volume is about 8 μl. FIG. 2 shows a conventional example of an LC system using such a flow cell. In the figure, reference numeral 1 denotes a column which is mounted in a column oven. Reference numeral 2 denotes a flow cell which is housed in a metal block 3 for shielding external light and stabilizing the temperature. Reference numeral 4 denotes a light source, and reference numeral 5 denotes a detection element (for example, a photodiode) of a UV detector. Of the incident light from the light source 4, only the light transmitted through the flow cell 2 is detected by the detection element 5 via an optical system (not shown). It is supposed to be. Column 1 is in the column oven, flow cell 2 is installed in the UV detector, and the column oven and U
Since it is provided in a housing separate from the V detector, the connection from the outlet of the column 1 to the inlet of the flow cell 2 is connected by a connection flow path 10. The outlet side of the flow cell 2 is directly connected to the drain so that the liquid sample after measurement is discharged. In addition, a liquid feed pump and a sample injection unit (not shown), which are well-known components of the LC, are provided on the front side of the column.

[0004] The LC system shown in FIG. 2 has a disadvantage that it is susceptible to unevenness in liquid temperature of the liquid sample and fluctuations in the liquid temperature. That is, if the liquid temperature fluctuates, the swelling of the baseline due to the temperature change will occur in the chromatogram data measured by the UV detector.
Therefore, it is necessary to reduce unevenness in the liquid temperature of the liquid sample and fluctuations in the liquid temperature. Therefore, as shown in FIG. 3, in the connection flow path 10 from the column 1 to the flow cell 2, the metal block 3 has a function as a heat exchanger, and the connection flow path 1
0 is wound around the metal block 3 so as to suppress the fluctuation of the liquid temperature on the inlet side of the flow cell.

[0005]

In order to reduce the amount of a liquid sample to be consumed, for example, the flow cell to be used is reduced in internal diameter to a micro cell, and a system using a micro flow cell is used. There is. In the case of such a micro flow cell, in order to reduce the cell capacity, for example, a change is made to a cylindrical cell having an inner diameter of 0.8 mm and a length of 5 mm. When changing to such a micro flow cell, it is also necessary to reduce the fluctuation of the liquid temperature. However, when trying to stabilize the liquid temperature by using a method in which a liquid flow path is wound around a metal block as performed in a conventional cell of about 8 μl,
The piping from the column to the flow cell becomes longer, which causes a problem that the peak of the chromatogram spreads. In other words, when a microflow cell is used, if the length of the pipe after the column is long, the liquid sample separated by the column will spread again while flowing through the subsequent connection flow path, and the length of the pipe after the column will be long. You need to be careful.

Of course, it is best if the column and the cell can be directly connected, so that the spread of the peak can be suppressed. However, the column is mounted in a column oven which is a thermostat, and the flow cell is separated from the column oven. It is actually difficult to directly connect the column and the flow cell without passing through the connection flow channel because it is mounted inside the UV detector at the position, and a connection flow channel for connecting them is absolutely necessary. is there. Therefore, it is required in a system using a micro flow cell to make the connection flow path as short as possible. However, in the method of winding the connection flow path around a metal block as a heat exchanger as described above, a connection length of a considerable length is required. Since a flow path is required, it is difficult to simultaneously solve the problem of the spread of the chromatogram peak due to the length of the connection flow path and the problem of the baseline fluctuation of the chromatogram due to the thermal fluctuation of the liquid temperature. It is.

In the present invention, the liquid temperature is stabilized without using a conventional heat exchanger using a metal block.
It is an object of the present invention to provide an LC that can solve both of these problems at once.

[0008]

In order to solve the above problems, in a liquid chromatograph apparatus for detecting a liquid sample eluted from a column by introducing the liquid sample into a flow cell provided in a detection unit, a column outlet and an inlet of the flow cell are provided. At least a part of the flow path connecting the sides is a double pipe, and the liquid sample flowing from the column to the flow cell flows on the inner pipe side, and the liquid sample flows from the flow cell outlet on the outer pipe side. And

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a liquid chromatograph apparatus showing one embodiment of the present invention. In this figure, the same components as those in FIG.

In the drawing, reference numeral 11 denotes a discharge flow path (a);
Is a discharge channel (b), 13 is a discharge channel (c), and a general-purpose Teflon tube (with an inner diameter of about 500 μm) is used. The discharge channel (a) 11 has one end connected to the outlet of the flow cell 2 and the other end connected to the outer periphery of the inlet of the flow cell 2 so as to hermetically seal the T-joint 2.
0 is connected to one connection part. T-shaped joint 2
0 is connected to one end of a discharge channel (b) 12, and the other end of the discharge channel (b) 12 is tightly connected to the outer periphery of the outlet of the column 1 in a T-shape. It is connected to one connection part of the joint 21. Then, the discharge channel (c) 1 is connected to the remaining one connecting portion of the T-shaped joint 21.
3 are connected. The fluid flowing out from the outlet of the flow cell 2 is discharged to the discharge flow path (a) 11 and the T-shaped joint 2.
0, a discharge passage (b) 12, a T-shaped joint 21, and a discharge passage (c) 13 to be discharged to a drain (not shown).

The outlet of the column 1 communicates with one end of the connection channel 10 as in the conventional example of FIG. 2, and the other end of the connection channel 10 is connected so as to communicate with the outlet of the flow cell 2. . The connection flow path 10 is a fused silica tube (with an inner diameter of about 50 to 100 μm and an outer diameter of about 360 μm) and is inserted into the discharge flow path (b). That is, a double pipe is formed in which the connection flow path 10 is an inner pipe and the discharge flow path (b) is an outer pipe.

The length of the connection flow path (b) 12 is for connecting the column 1 in the column oven to the flow cell 2 in the UV detector. The length is determined by the layout of the internal design, but it goes without saying that it is desirable to make the length as short as possible.

Next, measurement with the present apparatus will be described. Send the mobile phase under the same liquid temperature conditions as before the analysis,
The mobile phase is allowed to flow through the discharge flow path (a) 11, the T-shaped joint 20, the discharge flow path (b) 12, and the T-shaped joint 21. Subsequently, the sample is introduced from a sample introduction unit (not shown), and the sample is sent into the column by the mobile phase, whereby the sample is separated into components and eluted from the outlet of the column 1. This eluted component is introduced into the flow cell 2 through the connection channel 10 (inner tube). Since the connection flow path 10 is in the discharge flow path (b) 12, the connection flow path 10 is covered by the mobile phase fluid that has flown in the discharge flow path (b) 12 and has been sent in earlier. Since the mobile phase fluid has a larger heat capacity than air and is supplied in advance under the same temperature condition as that of the analysis, the eluted fluid flowing in the connection flow path 10 is less susceptible to a change in external temperature, and is stable. It is sent into the flow cell 2 at a temperature. Therefore, the measurement can be performed in a state where the liquid temperature fluctuation is small, and as a result, the waviness of the baseline caused by the temperature fluctuation is reduced. Further, since the connection flow path 10 does not need to be wrapped around the metal block 3 due to the necessity of stable liquid temperature, the connection flow path 10 can be made the shortest length, so that the problem of the spread of the chromatogram peak is reduced. Can be done.

FIG. 4 shows a comparison of the chromatogram baseline fluctuation obtained by the conventional apparatus and the apparatus of the present invention. FIG. 4 (A) shows only the connection flow path from the column outlet to the flow cell. (B) shows a double pipe in which a discharge flow path is provided outside the connection flow path. Both use the same micro flow cell. As is clear from the figure, the chromatogram of (A) has a large undulation of the baseline, whereas the chromatogram of (B) has greatly improved the fluctuation of the baseline.

In this embodiment, the entire pipe from the column outlet to the flow cell inlet is a double pipe. For example, only the inside of the housing of the UV detector is a double pipe (that is, only a part of the connection flow path is a double pipe). Of course), it is needless to say that the effect of reducing the baseline fluctuation can be obtained as compared with the case where no double piping is used.

[0016]

As described above, in the liquid chromatograph of the present invention, since the connection flow path from the column to the flow cell is a double pipe, the liquid temperature fluctuation of the elution fluid flowing on the inner pipe side of the double pipe is described. And the volume from the column to the flow cell can be kept small. As a result, the baseline fluctuation can be reduced, and the problem of the spread of the chromatogram peak and the problem can be solved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a liquid chromatograph apparatus according to one embodiment of the present invention.

FIG. 2 is a configuration diagram of a conventional liquid chromatograph apparatus.

FIG. 3 is a configuration diagram of a conventional liquid chromatograph apparatus.

FIG. 4 is a diagram showing baseline fluctuation of chromatograms obtained by the liquid chromatograph of the present invention and a conventional liquid chromatograph.

[Explanation of symbols]

 1: Column 2: Flow cell 3: Metal block 4: Light source 5: Detection element 10: Connection channel (inner tube) 11: Discharge channel (a) 12: Discharge channel (b) (outer tube) 13: Discharge Channel (c)

Claims (1)

[Claims] In a liquid chromatograph apparatus for introducing a liquid sample eluted from a column into a flow cell in a detection unit, at least a part of a flow path connecting a column outlet side and a flow cell inlet side is formed as a double pipe, and A liquid chromatograph apparatus characterized in that a liquid sample flowing from a column to a flow cell flows on an inner tube side and a liquid sample flows from a flow cell outlet on an outer tube side.