JPH0426060B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a high-pressure metering pump device used in liquid chromatography and the like, which measures a fixed amount of liquid and discharges it to a column or the like.

[Prior art]

In conventional liquid chromatography, when measuring a fixed amount of a sample solution such as a solvent and discharging it into a column, for example, a ball valve is installed on the suction and discharge sides, and the rotational force of the motor is transferred via a cam to the reciprocating force of a plunger. As shown in Fig. 1, the sample liquid 2 in the solvent tank 1 was tested using the metering pump 3, controlling the discharge flow rate and discharge pressure by adjusting the stroke of the plunger and adjusting the rotation of the drive motor. The liquid is sent to the column 4 via the supply device S, but due to changes in the load pressure, for example, if the load pressure increases, the sample liquid supplied in the metering pump 3 may be compressed, or the inner wall or seals in the metering pump 3 may be compressed. This caused the member to bend, causing an error in the discharge flow rate.

On the other hand, in liquid chromatography, the chemical components of the mobile phase are changed as a function of a preset time. In other words, a gradient device is attached, and a microcomputer mixes single liquids to change the concentration and sequentially column the column. It is known that supplying analyte for analysis brings about effects such as improvement of separation power and shortening of separation time. Therefore, conventionally, as shown in FIG. 2, a single liquid such as methanol 5 is filled in a solvent tank 6 and water 7 is filled in a solvent tank 8, respectively, and a pump 9 for methanol 5 and a pump 10 for water 7 are pumped. is driven in a cooperative manner, the mixing ratio of each single liquid is changed by the control signal of the gradient device G including a microcomputer, the concentration is changed, and the sample is sent to the column 11 via the sample supply device S. Gradient elution was performed. However, these metering pumps 9 and 10 also have the same drawbacks as the metering pump 3 described above, namely, they do not have good constant flow accuracy against load pressure fluctuations, and they also require a high-pressure resistant structure that can withstand the separation load pressure of the column 11. , arranging multiple units would be economically burdensome.

[Purpose of the invention]

The present invention has been made in view of the above points, and is an inexpensive high-pressure quantitative determination method for liquid chromatography that uses a low-pressure pump, simplifies the structure of the pressure pump, and has excellent accuracy against fluctuations in load pressure. The purpose is to provide a pump device.

[Structure of the invention]

In order to achieve the above object, the present invention includes a first pump that delivers the test liquid by pressure control, a second pump that pressurizes the delivered test liquid, and a pump that pumps the pressurized test liquid. A third pump that measures and discharges, a pressure sensor that detects the suction pressure and discharge pressure of the third pump, and a first pump that maintains a preset difference between the suction pressure and discharge pressure of the third pump constant. The invention is characterized in that it is provided with a control circuit that provides feedback to the control circuit.

〔Example〕

An example of the present invention will be described below with reference to FIG.

This embodiment is a high-pressure metering pump device used for liquid chromatography, and the high-pressure metering pump device A connects a column 18 with solvent tanks 15, 16, and 17 that store single liquids 12, 13, and 14, respectively. A first pump 21, 22 of a low-pressure plumber type reciprocating type that outputs enough pressure to back up the plunger of the second pump 20 by setting the discharge pressure of the third pump 19 to a set pressure through pressure control in the flow path. ，
23, and a second reciprocating plunger type pump which is not equipped with a return spring for pressurizing the mixed sample liquid sent by the first pumps 21, 22, and 23.
A pump 20 and a third pump 19 of a plunger type reciprocating type that sucks, measures, and discharges the mixed sample liquid pressurized by the second pump 20 are provided, and the second pump 20 and the third pump 19 A pressure sensor 25 for measuring the suction pressure of the third pump 19 is attached to the connecting tube 24 that connects the third pump 19, and a third sensor 25 is attached to the connecting tube 26 that connects the third pump 19 and the sample supply device S.
A pressure sensor 27 that measures the discharge pressure of the pump 19
The first pumps 21, 22, 23 are connected to the pressure sensor 27 and the pressure sensor 25 in order to keep the difference between the suction pressure and the discharge pressure of the third pump 19 constant based on the signals from both pressure sensors. A control circuit 28 that calculates and controls the pressure is connected to the control circuit 28.

Furthermore, in this embodiment, the solvent tanks 15, 16, 17
The first pumps 21, 22, 23 pump a single liquid of
A gradient device G is provided, which includes a microcomputer that drives the microcomputer to change the mixing ratio of each single liquid to change the concentration of the mixed liquid, and sends control signals to each of the first pumps 21, 22, and I'm sending it.

With this configuration, for example, the solvent tanks 15, 1
Pump the single liquid from 6 and 17 and transfer it to the gradient device G.
The mixed test liquid is discharged by the low pressure type first pumps 21, 22, 23 at the pressure and flow rate set by the control circuit 28, and this 2 to 3 kg/cm ² G
With the discharge pressure of the first pumps 21, 22, and 23 of about 100 degrees, the plunger of the second pump 20 can back up and suck in the mixed sample liquid, making a return spring unnecessary. Then, by pressurizing the second pump 20, the mixed sample liquid is heated at a rate of, for example, 190 kg/cm ²
Since it is made to about G and is supplied into the third pump 19,
The mixed sample liquid sucked into the third pump 19 is already in a compressed state due to pressurization, and the third pump 1
Since the inner wall and sealing member inside the pump 9 are already bent, when the plunger of the third pump 19 is pushed out in this state, the mixed sample liquid inside the third pump 19 is slightly pressurized (for example, 200 kg/cm ² G). ) and is discharged into the column 18 via the sample supply device S in an accurately measured amount corresponding to the stroke of the plunger.

Therefore, the following effects of the embodiment can be achieved.

First, the first pump can be of various low-pressure types (eg, tube pump, gear pump, screw pump, tire flamm pump, etc.), and an inexpensive one can be selected.

Next, since the plunger type reciprocating type second pump does not require a return spring as described above, the motor torque during the discharge process of the plunger can be reduced and it can be manufactured at low cost. Note that a weak return spring capable of responding to the sliding resistance of the seal member (O-ring) may be provided within the pump. Furthermore, the sample liquid in the third pump has already been pressurized by the second pump and is in a compressed state, and the inner wall and sealing member in the third pump are already in a bent state. Regardless of load pressure fluctuations due to clogging, etc., a constant amount of liquid can be sent to the column by the stroke of the plunger, and highly accurate analysis results can be obtained.

In addition, even if the ball valve on the suction side is not closed for some reason when the third pump discharges, the second pump has already been discharged.
Since it is pressurized by a pump, analysis and measurement can be continued with an error that is at the level of noise.

Note that although three solvent tanks and the first pump were used in this embodiment, it is of course possible to apply to all three solvent tanks or more.

〔Effect of the invention〕

As explained above, the present invention provides a first
A pump, a second pump for pressurization, a third pump for metering, a pressure sensor that detects the suction and discharge pressure of the third pump, and a preset difference between the suction pressure and discharge pressure of the third pump that is maintained constant. first for
Since a control circuit that provides feedback to the pump is provided, a quantitative amount of the sample liquid corresponding to the stroke of the third pump's plunger can always be sent to the column, improving the accuracy of the analysis results. In addition, the first pump can be a low-pressure pump, and the spring for returning the plunger of the second pump for pressurization is removed, so the motor torque can be reduced, resulting in an inexpensive metering pump device for chromatography. I can do it.

[Brief explanation of drawings]

Figure 1 is a block diagram showing a conventional liquid chromatography metering pump, Figure 2 is a block diagram of a conventional system with a gradient device attached, and Figure 3 is an embodiment of the present invention with a gradient device attached. It is a block diagram. A is a high-pressure metering pump device, G is a gradient device, S is a sample supply device, 12, 13, 14 are single liquids, 15, 16, 17 are solvent tanks, 18 is a column,
19 is the third pump, 20 is the second pump, 21,2
2 and 23 are first pumps, 25 and 27 are pressure sensors, and 28 is a control circuit.

Claims (1)

[Scope of Claims] 1. A first pump that sends out a sample liquid through pressure control, a second pump that pressurizes the fed sample liquid, and a second pump that sucks in, measures, and discharges the pressurized sample liquid. 3 pumps, a pressure sensor that detects the suction pressure and discharge pressure of the third pump, and a control circuit that feeds back to the first pump to maintain a preset difference between the suction pressure and discharge pressure of the third pump. A high-pressure metering pump device for liquid chromatography having first, second, and third pumps. 2. The high-pressure metering pump device for liquid chromatography according to claim 1, wherein the second pump does not have a return spring for returning the plunger.