JPH05272449A - Liquid feeding system for liquid chromatograph - Google Patents

Abstract

PURPOSE:To perform liquid feeding suitable for plural analysis methods only by the normal-reverse rotation of both cams by devising a means for setting the cam profile of a parallel-connected double plunger pump in such a way as to make the total feed liquid quantity of both plunger pumps constant at the normal rotation time of the cams. CONSTITUTION:When a parallel-connected double plunger pump 14 is driven after switching a change-over valve 19 onto the discharge drum 20 side, the moving phase sucked from a reservoir part 10 is delivered to a column 17 through a pressure sensor 15 and an injector 16. The respective components of a sample injected by the injector 16 are separated by the column 17 and detected by a detector 18. In the case of applying a single stage separation method, both cams of the pump 14 are rotated clockwise to hold total discharge quantity always constant and to perform precison liquid feeding. In the case of applying a recycle separation method, the change-over valve 19 is switched onto the recycle pipe 21 side to recycle the eluate having passed the detector 18, and simultaneously, both cams are rotated reversely to hold total suction quantity always constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a precision plunger pump used in a high performance liquid chromatographic analyzer, a preparative liquid chromatograph, and the like.

[0002]

2. Description of the Related Art In order to increase the degree of separation in an analytical or preparative liquid chromatograph, a method called a recycle separation method in which the eluent from the column is reintroduced into the column is effective. In this, as shown in FIG. 1, the eluent that has flowed out of the column 17 (and the detector 18) is connected to the pipe 13 on the suction port side of the pump 14 and is fed into the column 17 again by the pump 14. By repeating this recycling, it is possible to obtain the same high separation effect as when the column length is made very long.

However, a problem in the recycle separation method is the diffusion of the sample in the path for recycling the eluent from the column 17 (the pipe 21, the confluence 12, the pipe 13, the pump 14, the injector 16, etc.). Usually, a precision plunger pump is used in a liquid chromatograph, but since the plunger pump has a separate discharge stroke and suction stroke, sample diffusion becomes significant when the flow rates in both strokes are significantly different. Therefore, conventionally, when the recycling separation method is performed, a parallel type double plunger pump in which the difference in flow rate between discharge and suction is small and the non-suction time is short is used.

FIG. 2 shows a schematic structure of a parallel type double plunger pump. As the name suggests, the parallel type double plunger pump 14 has two plunger pumps 23, 24.
Are arranged in parallel so as to have a common suction port 25 and a common discharge port 26.
Plungers 27, 28 driven by respective cams 29, 30 are provided on 3, 24. Both cams 2
9 and 30 are fixed so that the rotational phase difference between them is always constant, and are rotationally driven by a single motor at a constant speed.

Cam 2 of both plunger pumps 23, 24
As shown in FIG. 3B, in the cam profiles of 9 and 30, the sum of the discharge flow rates of both plunger pumps 23 and 24 (that is, the flow rate at the discharge port 26 of the parallel double plunger pump 14) is always constant. Is designed to be. For this reason, in the usual single-stage separation method (method without recycling), diffusion in the column is small, and high-precision separation can be performed.

[0006]

The parallel type double plunger pump is characterized in that the difference in flow rate between discharge and suction is small and the non-suction time is short as compared with a single plunger pump, a series dual plunger pump and the like. Therefore, as described above, it is considered to be the most suitable pump at present when performing the recycling separation method. However, originally, the parallel type double plunger pump 14
Is designed to keep the discharge flow rate constant, so the flow rate during suction (shown by the curve below the time axis) is not constant as shown in FIG. 3 (b). , Is pulsating, and there is a non-suction period for a short time.

As shown in FIG. 4 (a), at the confluence 12 on the pump suction side when the recycling separation method is performed,
When the suction stroke ends while the sample 40 is being sucked and the non-suction period starts, the eluent that is pushed out from the column side (is pushed out at a constant flow rate from the discharge side of the pump 14) As shown in FIG. 4 (b), it is pushed out toward the mobile phase reservoir 10 side pipe 11. Therefore, diffusion of the sample 40 easily occurs,
This causes deterioration of the separation (widening the peak band in the detector 18 during analysis).

The present invention has been made to solve such a problem, and its object is to minimize the diffusion of a sample when a recycling separation method is used, and to use an ordinary single sample. It is an object of the present invention to provide a liquid delivery system for a liquid chromatograph capable of precisely delivering a liquid at a constant flow rate when the step separation method is used.

[0009]

The liquid delivery system for a liquid chromatograph of the present invention made to solve the above-mentioned problems comprises a) two plunger pumps arranged in parallel. The cam profile of the cam is
A parallel type double plunger pump that is set so that the total liquid feed amount of both plunger pumps is constant when the cam rotates forward, and b) between the discharge port and column inlet of the parallel type double plunger pump, and the double plunger. The inlet of the pump,
It is characterized by comprising a mobile phase storage part, a recycle pipe connecting the three sides of the column outlet, and c) a rotary drive source for rotating both cams of the parallel type double plunger pump in the forward and reverse directions.

[0010]

When performing the liquid chromatograph using the recycling separation method, both cams are reversed by the rotary drive source c. As a result, the suction amount of the parallel double plunger pump becomes constant, and the eluent recycled from the column outlet is sucked into the parallel double plunger pump at a constant flow rate. Therefore, even at the confluence point (the point where the pipe from the mobile phase reservoir and the pipe from the column outlet meet) in front of the suction port of the recycle pipe b, the sample smoothly flows into the parallel double plunger pump side, and the diffusion is minimized. It can be suppressed to the limit.

When performing a liquid chromatograph by the normal single-stage separation method, the cam is rotated in the forward direction by the rotary drive source c. As a result, the mobile phase can be precisely delivered from the parallel double plunger pump a to the column at a constant flow rate as in the conventional case.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the construction of a liquid chromatograph apparatus which is one embodiment of the present invention and which can carry out a recycling separation method. In the liquid chromatograph apparatus of this embodiment, the pump 14 and the pressure sensor 1 are provided so that the measurement can be performed by both the normal single-stage separation method and the recycle separation method.
5, a pipe for connecting the injector 16, the column 17, and the detector 18 in series, and a recycle pipe 21 for introducing the eluent from the outlet of the detector 18 to the suction port side of the pump 14 is provided. The column 1 is provided on the outlet side of the detector 18.
A switching valve 19 for switching the destination of the eluent from 7 to the recycling pipe 21 side and the discharge tank 20 side is provided, and the pump 14
On the suction port side, the pipe 11 from the mobile phase reservoir 10 and the recycle pipe 21 are merged at a merge point 12. As the pump 14, the parallel type double plunger pump 14 having the structure shown in FIG. 2 is used, but unlike the conventional parallel type double plunger pump,
A motor capable of rotating in the forward and reverse directions is used so that the cams 29 and 30 can be rotated in both the forward and reverse directions. First, the operation of each part when the measurement is carried out by the normal single-stage separation method in this liquid chromatograph will be described.

First, the switching valve 19 is switched to the discharge tank 20 side. The mobile phase sucked from the mobile phase storage unit 10 through the pipe 11 by the pump 14 is detected by the pressure sensor 15.
And to the column 17 through the injector 16. When the sample is injected in the injector 16,
Each component of the sample is separated in the column 17 and detected by the detector 18 for each component. The eluent that has passed through the detector 18 is discharged from the switching valve 19 to the discharge tank 20.

When used in the single-stage separation method, both cams 29 and 30 of the parallel type double plunger pump 14 are normally rotated. At this time, the suction / discharge flow rates of the plunger pumps 23, 24 constituting the parallel type double plunger pump 14 are as shown in FIG.
The total discharge amount of 24 is always constant. Therefore, it is possible to perform precise liquid feeding to the column 17.

When the liquid chromatographic apparatus of this embodiment is used in the recycling separation method, the switching valve 19 is switched to the recycling pipe 21 side. Thereby, the detector 18
The eluent that has passed through is recycled through the pipe 21,
It enters the pipe 13 at the confluence 12 and is again sucked from the suction port of the parallel double plunger pump 14. By such a recycling route, the degree of separation of each component of the sample gradually increases while repeatedly passing through the column 17, so that highly accurate liquid chromatographic measurement can be performed.

When performing this recycling separation method, in the liquid chromatograph apparatus of this embodiment, both plunger pumps 23, 2 constituting the parallel type double plunger pump 14 are used.
The cams 29 and 30 of No. 4 are reversely rotated. At this time, the suction / discharge flow rate of each plunger pump 23, 24 is as shown in FIG.
The graph of FIG. 3B is turned upside down as shown in FIG. 3A, and contrary to the above, the total suction amount is always constant. Therefore, at the confluence point 12, there is no return of the sample liquid to the mobile phase reservoir 10 side as shown in FIG. Can be done.

When the cams 29 and 30 are reversed,
The pulsating flow on the discharge side of the parallel type double plunger pump 14 becomes large, but this pulsating flow is absorbed by the pressure and large volume of the column 17, and becomes a smooth flow at the place where it exits the detector 18. Therefore, the smooth flow is not disturbed at the confluence 12.

[0018]

In the liquid feeding system according to the present invention, the cam may be rotated in the forward direction when the analysis is performed by the single-stage separation method, and the cam may be rotated in the reverse direction when the analysis is performed by the recycling separation method. As a result, the most suitable liquid transfer can be performed in each case, and precise analysis can be performed in any case.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a liquid chromatograph device which is also an embodiment of the present invention and which can also perform a recycling separation method.

FIG. 2 is a configuration diagram of a parallel type double plunger pump.

FIG. 3 is a discharge / suction process diagram (a) when the cam of the parallel type double plunger pump of the present embodiment is rotated in the reverse direction, and a discharge / suction process diagram (b) when the cam is rotated in the normal direction.

FIG. 4 is an explanatory view for explaining the movement of the sample at the confluence of the pipe from the mobile phase reservoir and the recycle pipe.

[Explanation of Codes] 14 ... Parallel Double Plunger Pump 21 ... Recycle Pipe 23, 24 ... Plunger Pump 29, 30 ... Cam 40 ... Sample

Claims (1)

[Claims] 1. A) comprising two plunger pumps arranged in parallel, and the cam profiles of the cams of both plunger pumps are set so that the total liquid feed amount of both plunger pumps is constant during normal rotation of the cams. Parallel type double plunger pump, and b) between the discharge port and the column inlet of the parallel type double plunger pump, and the suction port of the double plunger pump,
For a liquid chromatograph, which comprises a mobile phase reservoir, a recycle pipe connecting the column outlet to three sides, and c) a rotary drive source for rotating both cams of the parallel double plunger pump in the forward and reverse directions. Liquid delivery system.