JP2573671B2 - Mobile phase feeder for supercritical fluid chromatography - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is used for a supercritical fluid chromatograph (hereinafter, referred to as SFC), and particularly for liquefied gas or supercritical fluid having a predetermined pressure of several μl / min. The present invention relates to a mobile phase supply device suitable for delivery.

[Prior Art] For example, in a capillary column SFC, the mobile phase flow rate is extremely small at several μl / min. On the other hand, a reciprocating pump, for example, a plunger pump, is capable of continuous liquid feeding, but has a capacity of 0.
When used at 1 ml / min or less, pulsation is large and inappropriate.

For this reason, conventionally, a reciprocating pump used in a high-performance liquid chromatograph has not been used for a capillary column supercritical fluid chromatograph, and a screw-driven syringe pump has been used exclusively.

[Problems to be Solved by the Invention] However, in SFC, a liquefied gas such as carbon dioxide is often used as a mobile phase, and a relatively large amount (several to several tens of ml) of a liquefied gas is stored in a syringe of a syringe pump. Due to the necessity, the syringe pump becomes substantially the same as the high-pressure gas container, and in order to maintain its safety, it must be designed in accordance with the high-pressure gas control law, which is expensive.

In the case of capillary SFC, it is necessary to minimize the sample injection volume to several μl or less, and the pressure of the mobile phase is several hundred b.
Since it is as high as ar or less, the flow path formed in the sample injector must be instantaneously switched to supply the sample to the column side, and a desired minute amount of sample cannot be supplied to the column side.

Furthermore, when the outlets of the two syringe pumps are connected in common and the liquefied gas is mixed with the modifier solvent, a very small flow of a few percent of the liquefied gas is supplied to the liquefied gas. Because of the necessity of liquid, the mixing ratio of the two cannot be made substantially constant.

A first object of the present invention is to provide an SFC mobile phase supply device capable of sending a mobile phase having a predetermined pressure at a flow rate of several μl / min using a relatively inexpensive reciprocating pump.

A second object of the present invention is to provide an SFC mobile phase supply device capable of supplying a desired minute amount of sample to an SFC column using a sample injector.

A third object of the present invention is to provide a mobile phase supply for an SFC capable of maintaining the pressure of a mobile phase to be supplied at a predetermined value and maintaining a mixing ratio of a liquefied gas or a supercritical fluid to a modifier solvent at a predetermined value. It is to provide a device.

[Means for Solving the Problems and Their Effects] In order to achieve this object, in the SFC mobile phase supply device according to the present invention, an outlet is connected to an inlet of a supercritical fluid chromatograph via a flow path. A first reciprocating pump for delivering a liquefied gas or a supercritical fluid, and a back pressure adjustment connected to a flow path branched from a flow path between an outlet of the first reciprocating pump and a column inlet of the supercritical fluid chromatograph. And a device.

When the present invention is applied to a capillary column SFC,
The ratio (split ratio) between the flow rate of the fluid flowing to the capillary column side and the flow rate of the fluid flowing to the back pressure regulator side is SF
It is determined by the set flow rate of the resistance pipe of C and the first reciprocating pump and the set pressure of the back pressure adjusting device. Therefore, by changing the set flow rate of the first reciprocating pump while keeping the set pressure of the back pressure adjusting device constant, the split ratio can be changed. Can be supplied to the side.

Conventionally, all the liquefied gas in the syringe pump has been pressurized beyond the critical pressure.However, only the liquefied gas in the internal volume of the reciprocating pump needs to be pressurized. The supply device can be provided at low cost, and the safety against high-pressure gas is improved.

When the liquefied gas is a non-polar solvent and the polar sample is separated into components, the above-described configuration further includes a flow path between the outlet of the first reciprocating pump and the branch point or the inlet of the first reciprocating pump. Then, a mobile phase supply device for SFC to which a second reciprocating pump for feeding a modifier solvent is connected via a flow path is used.

Since this modifier solvent is also diverted at the above split ratio, the flow rate of the second reciprocating pump can be made relatively large, so that even if this split ratio fluctuates (when applied to a recycle chromatograph),
The liquefied gas and the modifier solvent can be supplied to the column while maintaining a constant mixing ratio. Thereby, the holding time of the SFC and the baseline of the output of the detector are stabilized.

The outlet side flow path of the back pressure adjusting device is connected to, for example, the atmosphere or connected to the inlet of the first reciprocating pump, and the outlet side flow path (return flow path) is connected to the inlet side of the first pump. Alternatively, flow path switching means for selectively switching to the atmosphere side is provided. In the latter connection, the consumption of the liquefied gas can be extremely reduced.

Either of the above fluid supply devices is connected to a capillary column SFC
When connecting to the SFC, the outlet of the first reciprocating pump is connected to the inlet of the SFC via a flow path, and the back pressure adjusting device is connected to the sample injector of the supercritical fluid chromatograph and the inlet of the capillary column. Is connected to the flow path branched from the flow path between.

With this connection, the sample is also split into the capillary column and the back pressure adjusting device at the split ratio, so that a very small amount of sample can be supplied to the capillary column. Also, since the split ratio can be changed by changing the flow rate of the first reciprocating pump, a desired minute amount of sample is supplied to the capillary column side even when the mobile phase pressure is 100 bar or more. be able to.

Also, recycle any of the above fluid supply devices using SFC
In the case of connecting to the first reciprocating pump, the outlet of the first reciprocating pump is connected to the flow path between the flow path switching means of the recycle SFC and the circulation pump via the flow path. In this recycled SFC, the circulation pump, the sample injector, the column, the detector, and the flow path switching means are connected in a loop in this order, and the flow path switching means has a back pressure having an open end. An adjusting device or a resistance tube is connected, and the flow path on the detector side is switched to the circulation pump side or the open end side by the flow path switching means.

Recycling optimizes the separation of sample components,
When the unnecessary component or the component to be separated is detected by the detector C, the switching means is set to the open end side to discharge this component to the outside. During this discharge, the mobile phase is replenished into the loop from the fluid supply device, and the pressure on the inlet side of the circulating pump is maintained at the set pressure of the back pressure regulator, so the pressure in the loop drops below the critical pressure. Unnecessary components can be discharged or specific components can be fractionated without causing this.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

(1) First Embodiment FIG. 1 shows a case where a fluid supply device is applied to a capillary column SFC.

This capillary SFC basically consists of a sample injector 10,
Capillary column 12, detector 14, resistance tube 16 and detector 18
Are connected in series.

The capillary column 12 is, for example, a hollow column using a fused silica tube having an inner diameter of 50 μm. Also,
The resistance tube 16 is usually selected to have a flow rate of several μl / min in a pressure range of 100 to 300 bar. Detector 14 is generally one
A detector that can detect a sample component under a high pressure of 00 bar or more, for example, a UV detector, and the detector 18 is a detector that detects under atmospheric pressure, for example, a hydrogen salt ionization detector (FID). It is not always necessary to provide two detectors, and either one may be used. However, when a modifier solvent is used, the FID
In general, only a UV detector is used.

A preheating coil 20 is connected to the upstream side of the sample injector 10,
The preheating coil 20, the sample injector 10, the capillary column 12, and the resistance tube 16 are housed in a constant temperature bath 22 for maintaining the mobile phase at a predetermined value equal to or higher than the supercritical temperature.

The mobile phase supply device for supplying a mobile phase of a predetermined pressure to the capillary SFC is basically composed of a reciprocating pump 24 connected to the inlet of the preheating coil 20 by a pipe to feed a set flow rate, and a sample injection. And a back pressure adjusting device 26 connected to a pipe branched from a point B on the pipe connecting the vessel 10 and the capillary column 12.

The reciprocating pump 24 is usually of a plunger type. Pump head 24a and pump head 2 of reciprocating pump 24
The cooling coil 24b connected to the inlet of 4a is arranged in the cooling jacket 24c. The inside of the cooling jacket 24c is kept below the critical temperature of the mobile phase by the cooler 28, and the mobile phase in the pump head 24a is turned into a liquid phase.

The back pressure adjusting device 26 includes a pressure adjusting valve 26a, and a pressure indicating adjuster 26b that detects the upstream pressure of the pressure adjusting valve 26a and controls the pressure adjusting valve 26a to maintain the pressure at a set pressure. The pressure adjusting valve 26a is, for example, a valve rod vibrating electromagnetic valve that moves a valve rod in the axial direction and completely closes the flow path when the pressure is equal to or lower than a set pressure, and fully opens the flow path when the pressure exceeds the installation pressure. By the back pressure adjusting device 26, the pressure in the preheating coil 20 is set to a set value equal to or higher than the critical pressure.

A liquefied gas 29 such as carbon dioxide used as a mobile phase is stored in a cylinder 30. The cylinder 30 is connected to the inlet of the cooling coil 24b via a stop valve 32 and a check valve 34 by piping.

Here, in order to elute a polar sample using a non-polar fluid such as carbon dioxide as a mobile phase, it is necessary to mix a polar solvent such as alcohol as a modifier solvent with the mobile phase. Further, in order to keep the peak retention time constant, it is necessary to keep the mixture ratio of the two constant.

Therefore, the storage tank 38 containing the modifier solvent 36
Is connected to the inlet of a reciprocating pump 40 that sends a set flow rate by piping, and the outlet of the reciprocating pump 40 is connected between the check valve 34 and the cooling coil 24b via a stop valve 42 and a check valve 44 by piping. Connected to the piping.

Next, the operation of the present embodiment configured as described above will be described for the case where only the liquefied gas 29 is used as the mobile phase.

In the initial state, the stop valves 32 and 42 are closed, and the reciprocating pumps 24 and 40 are stopped. By driving the cooler 28, the inside of the cooling jacket 24c is set to a set value below the boiling point,
The inside of the thermostat 22 is set to a set value equal to or higher than the critical temperature, and the set pressure of the pressure indicating controller 26b is set to a predetermined value equal to or higher than the critical pressure. Next, the stop valve 32 is opened, the reciprocating pump 24 is driven, and the liquefied gas 29 at a set flow rate is sent to the capillary SFC to clean the flow path. When the liquefied gas 29 passes through the preheating coil 20, it becomes a supercritical fluid. A part of the supercritical fluid passes through the back pressure adjusting device 26, and the rest is supplied to the capillary column 12. The supercritical fluid that has passed through the back pressure adjusting device 26 is decompressed to atmospheric pressure, becomes gas, and is released into the atmosphere.

Ratio of the flow rate of the fluid flowing to the capillary column 12 side to the flow rate of the fluid flowing to the back pressure adjusting device 26 side (split ratio)
Is a set flow rate and back pressure adjusting device for the resistance pipe 16 and the reciprocating pump 24
It is determined by the set pressure of 26. Since a specific resistance tube is used, the split ratio can be changed by changing the set flow rate of the reciprocating pump 24 while keeping the set pressure of the back pressure adjusting device 26 constant. For example, if the discharge flow rate of the reciprocating pump 24 is set to 0.1 ml / min and a resistance tube having a flow rate of 1 μl / min under a predetermined pressure at the column inlet determined by the back pressure adjusting device is used, a minute flow rate of 1 μl / min and a pulsation The sample injection split ratio can be reduced to 1/99 while supplying a small mobile phase to the capillary column 12.

Conventionally, all fluids in the syringe pump (from several tens to
The pressure (about 100 ml) exceeded the critical pressure (72.8 bar for carbon dioxide).
Since only a liquefied gas (approximately ml) needs to be pressurized, the pressure resistance structure is simplified, the fluid supply device can be provided at low cost, and the safety against high-pressure gas is improved.

When a sample is injected into the sample injector 10 and the internal flow path is switched to mix this sample into the mobile phase, this sample is also split into the capillary column 12 and the back pressure regulator 26 at the split ratio. . For example, when 5 μl of the sample is injected into the capillary column 12, the split ratio becomes 1/99.
Then, a very small amount of a sample of 0.05 μl can be supplied to the capillary column 12 side. Further, since this split ratio can be changed by changing the flow rate of the reciprocating pump 28, even if the mobile phase pressure is 100 bar or more, a desired minute amount of sample is supplied to the capillary column 12 side. be able to.

The sample passes through a capillary column 12 and is separated into its components, which are detected by a detector 14 and further detected by a detector 18 through a resistance tube 16.

For polar samples, reciprocating pump together with reciprocating pump 24
When the discharge pressure of the reciprocating pump 40 becomes equal to or higher than the operation pressure, the stop valve 42 is opened, and the modifier solvent 36 is supplied at a set flow rate to be mixed with the liquefied gas 29. The mixing ratio of the liquefied gas 29 and the modifier solvent 36 is, for example, 9: 1. For example, the reciprocating pump 24 feeds 1 ml / min, and the reciprocating pop 40 feeds 0.1 ml / min. With such a flow rate, the mixing ratio can be kept almost constant. in this case,
The flow rates of the carbon dioxide and the modifier solvent supplied to the capillary column 12 are minute flow rates of 10 μl / min and 1 μl / min, respectively, which are flow rates at which the mixing ratio could not be made constant in the past.

The confluence of the liquefied gas 29 and the modifier solvent 36 may be a point on the flow path between the outlet of the pump head 24a and the inlet of the preheating coil 20.

(2) Second Embodiment FIG. 2 shows a configuration of a second embodiment in which the fluid supply device is applied to a capillary SFC. In the second embodiment, the outlet of the pressure regulating valve 26a is connected to the inlet-side flow path of the cooling coil 24b via a three-way valve 46 by piping. Other points are the same as those in FIG.

If modifier solvent 36 is used, three-way valve 46
Is switched to the atmosphere side. This is because part of the modifier solvent 36 cannot return to the reciprocating pump 24 side because the outlet pressure of the pressure regulating valve 26a becomes lower than the critical pressure and the modifier solvent 36 adheres to the inner wall of the pipe, and the liquefied gas 29 and This is to prevent the mixing ratio with the modifier solvent 36 from becoming constant.

When only the liquefied gas 29 is used as the mobile phase, when the sample is being supplied from the sample injector 10 to the capillary column 12 side, the three-way valve 46 is switched to the atmosphere side, and the sample is supplied to the inlet side of the reciprocating pump 24. Avoid being returned to After a certain period of time has passed after the sample injection, the sample
After it no longer exists in the flow path between the two, the three-way valve 46 is switched to the reciprocating pump 24 side. As a result, the consumption of the liquefied gas 29 can be extremely reduced as compared with the first embodiment.

(3) Third Embodiment FIG. 3 shows a configuration of a third embodiment in which the fluid supply device is applied to a recycled SFC.

Basically, the recycling SFC has a loop-shaped circulation pump 48 for maintaining a flow rate at a predetermined value, a sample injector 10, a column 12A filled with a stationary phase, a detector 14, and a three-way valve 50 for switching a flow path. A back pressure adjusting device 52 is connected to the port C of the three-way valve 50 in order to discharge the mobile phase to the outside while maintaining the back pressure at a set value equal to or higher than the critical pressure. The flow path between the ports AB of the three-way valve 50 forms a part of this loop. The pressure regulating valve 52 has the same configuration as that of 26, and includes a pressure regulating valve 52a and a pressure indicating regulator 52b.

The mobile phase supply device is basically the same as that shown in FIG. However, in FIG. 2, the preheating coil 20 and the sample injector 10 are connected to the pipe between the outlet of the reciprocating pump 24 and the connection point B, but in the present embodiment, the sample injector 10 The preheating coil 20 is connected to an inlet of a circulation pump 48. The outlet of the reciprocating pump 40 is connected to the pipe between the outlet of the reciprocating pump 24 and the connection point B via a stop valve 42 and a check valve 44 by a pipe. Other configurations are the same as those in FIG.

Since the flow rate in this loop is, for example, 0.15 ml / min,
There is no problem in that the sample injector 10 is arranged downstream of the connection point B.

Next, the operation when only the liquefied gas 29 is used as the mobile phase will be described.

The inside of the cooling jacket 24c is set to a predetermined value below the boiling point by the cooler 28, and the inside of the constant temperature bath 22 is set to a predetermined value above the critical temperature.
In addition, the set pressure of the pressure indicating controllers 26b and 52b is set to a predetermined value equal to or higher than the critical pressure. Further, the three-way valve 46 is switched to the atmosphere side, the three-way valve 50 is switched to the back pressure regulator 52 side, the stop valve 32 is opened, and the reciprocating pump 24 and the circulating pump 48 are driven to clean the flow path.

Next, the three-way valve 46 is switched to the reciprocating pump 24 side,
Switch 50 to the circulation pump 48 side. Since the sample injector 10 is provided on the downstream side of the connection point B, the three-way valve 46 can be switched to the reciprocating pump 24 regardless of the sample injection. When the mobile phase passes through the preheating coil 20, it becomes a supercritical fluid and circulates through the loop. After the steady state, the sample is injected into the sample injector 10, the internal flow path of the sample injector 10 is switched, and the sample is guided into the loop. As a result, column 12
In A, the sample is separated into components, and the degree of separation increases as the number of times the mobile phase circulates in the loop increases. If the spread of the peak outside the column 12A is ignored, the effective length of the separation column is equal to the length of the column 12A multiplied by the number of circulations of the mobile phase.

When the undesired components are appropriately separated and detected by the detector 14, the three-way valve 50 is switched to the back pressure adjusting device 52 side to discharge it to the outside. During this discharge, the mobile phase is supplied into the loop from the fluid supply device, and the pressure on the inlet side of the circulation pump 48 is maintained at the set pressure of the back pressure regulator 26. Unnecessary components can be discharged without lowering the temperature.

Next, when the component to be separated and purified is detected by the detector 14, the three-way valve 50 is switched to the circulation pump 48 side, and when the degree of separation of this component becomes appropriate, the three-way valve
By switching 50 to the back pressure adjusting device 52 side, only desired components are collected in the container 54.

When the modifier solvent 36 is used, as in the second embodiment, the three-way valve 46 is switched to the atmosphere side, the reciprocating pump 40 sends the modifier solvent 36 at a set flow rate, and the split ratio is changed. Regardless, the mixing ratio of the liquefied gas 29 and the modifier solvent 36 is kept constant.

[Brief description of the drawings]

FIGS. 1 to 3 relate to an embodiment of the present invention. FIG. 1 is a flow chart of a fluid supply device of a first embodiment in which the present invention is applied to a capillary column supercritical fluid chromatograph. Flow diagram of a fluid supply device of a second embodiment in which the present invention is applied to a capillary column supercritical fluid chromatograph. FIG. 3 shows a fluid supply device of a third embodiment in which the present invention is applied to a recycle supercritical fluid chromatograph. FIG. In the figure, 10 is a sample injector 12 is a capillary column 12A is a column 14, 18 is a detector 16 is a resistance tube 20, a preheating coil 22, a thermostatic bath 24, 40 is a reciprocating pump 24a, a pump head 24b, a cooling coil 24c, and a cooling coil 24c. Jackets 26 and 52 are back pressure regulators 26a and 52a are pressure regulators 26b and 52b are pressure indicator regulators 28 are coolers 29 are liquefied gases 30 are cylinders 32, 42 are stop valves 34 and 44 are check valves 36 are modifiers Solvent 38 is a storage tank 46, 50 is a three-way valve 48 is a circulation pump

Claims (6)

(57) [Claims] An outlet is connected to an inlet of a supercritical fluid chromatograph via a flow path, and a first reciprocating pump (24) for delivering a liquefied gas or a supercritical fluid; an outlet of the first reciprocating pump; A back pressure regulator (26) connected to a flow path branched from a flow path between the column and the column inlet of the supercritical fluid chromatograph, and a mobile phase supply device for a supercritical fluid chromatograph. . 2. The method according to claim 1, further comprising a flow path connected to a flow path between an outlet of the first reciprocating pump and the branch point or an inlet of the first reciprocating pump, the flow path being connected to a modifier solvent. Second reciprocating pump (4
0) A fluid supply device for supercritical fluid chromatography, comprising: 3. The apparatus according to claim 1, wherein the outlet-side flow path of the back pressure adjusting device is connected to the atmosphere. 4. An outlet of the back pressure adjusting device (26) is connected to an inlet of the first reciprocating pump (24) via a return flow path, and the first pump is connected to the return flow path. 3. The apparatus according to claim 2, further comprising a flow path switching means (46) for selectively switching to an inlet side or an atmosphere side of the air conditioner. 5. An outlet of said first reciprocating pump (24) is connected to an inlet of a supercritical fluid chromatograph using a capillary column (12) via a flow path, and said back pressure adjusting device (26). 5. The supercritical fluid chromatograph is connected to a flow path branched from a flow path between a sample injector (10) of the supercritical fluid chromatograph and an inlet of the capillary column (12). 6. Equipment. 6. An outlet of the first reciprocating pump (24) is connected to a flow path between a detector of a recycle supercritical fluid chromatograph and a circulation pump through a flow path. Item 5. The apparatus according to Item 4.