JPH0762991B2 - Liquid supply device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is desirable in that a splitter is provided in a flow path for transporting a liquid from a high pressure region to a low pressure region, and a part of the liquid is branched and discharged by the splitter. The present invention relates to a liquid supply device that supplies a liquid at a flow rate to a supply destination.

[Prior Art] When a liquid sample is supplied to an analysis device or the like for analysis, if the analysis device has a limited introduction capacity, a splitter is provided in the middle of the supply passage to branch and discharge the excess liquid, It is common to supply a desired flow rate of liquid to the analyzer according to the side introduction capacity.

By the way, as a method for supplying a sample solution to an ion source of a mass spectrometer for ionization, as described in JP-A-61-116065 and JP-A-62-163250, the sample solution is introduced into an ionization chamber. There is a method in which a porous member is attached to the tip of the introducing tube, and the sample solution is ionized by being exuded into the ionization chamber through the porous member.

FIG. 5 is a schematic diagram showing the structure of the sample introduction part of such an ion source. In the figure, 1 is a liquid chromatograph, 2 is an ionization chamber, 3 is an introduction pipe for carrying the sample liquid from the liquid chromatograph to the ionization chamber, 4 is a porous member attached to the tip thereof, and 5 is an excess sample liquid at the attachment portion. Is a discharge pipe for splitting, and 6 is a flow rate adjusting valve connected to the discharge pipe.

In such an introduction method, the amount of liquid sent from the liquid chromatograph is about 10 to 100 μ / min, while the flow rate of the sample liquid supplied into the ionization chamber through the porous member is about 1 μ / min. The split ratio is about 1:10 to 1: 100.

[Problems to be Solved by the Invention] When sending a small amount of liquid with such a large split ratio,
Fluctuations in the flow rate of the flow rate adjusting valve 6 or fluctuations in the amount of liquid sent from the liquid chromatograph have a great influence on the flow rate of the sample liquid introduced into the ionization chamber.

For example, when the sample liquid sent from the liquid chromatograph 1 at a flow rate of 101 μ / min is split into the porous member 4 at a rate of 1 μ / min and into the discharge pipe 5 at a rate of 100 μ / min, the adjustment valve 6 When the flow rate fluctuates by about ± 0.5% (0.5 μ / min) due to a change in conditions such as a temperature change, the flow rate of the sample liquid passing through the porous member 4 is 1 even if the fluctuation is only 0.5% for the adjusting valve. It changes by ± 0.5μ / min, which is actually 50%. This is the same even when the amount of the sample liquid sent from the liquid chromatograph changes, and thus stable ionization becomes difficult.

The present invention has been made in view of the above points, and provides a liquid supply device capable of performing stable supply with extremely small flow rate variation even when a small amount of liquid is sent at a large split ratio. Has an aim.

[Means for Solving the Problems] In order to achieve this object, the present invention provides a splitter in a flow path for carrying a liquid from a region having a high pressure to a region having a low pressure, and allows the liquid taken out through the splitter to flow. In a liquid supply device adapted to supply to the low pressure region via a flow path having a channel resistance, a gas of a constant pressure is supplied to the excess liquid discharge flow path of the splitter to make the excess liquid discharge flow path constant. It is characterized in that it is configured to apply pressure.

[Operation] In the present invention, since the gas to which the constant pressure is applied is supplied from the splitter to the flow path for discharging the excess sample liquid, the pressure in the flow path connecting the splitter and the supply target is constant even if the flow rate changes. Kept in. Therefore, the flow rate of the liquid sent from the splitter to the supply target portion can be kept constant.

An embodiment of the present invention will be described in detail below with reference to the drawings.

[Embodiment] FIG. 1 is a schematic view showing an example of an embodiment in which the present invention is applied to an electron impact ionization (EI) ion source, and the same components as those in FIG. There is. In FIG. 1, electrons generated from the filament 7 enter the ionization chamber 2 through the entrance port 8 and reach the collection electrode 10 through the exit port 9. The sample ions generated by the impact of the electrons are extracted through the outlet 11 and are accelerated and focused by the slit electrode 12. Reference numeral 13 is an insulating pipe that integrally holds the introduction pipe 3, the discharge pipe 5, and the porous member 4, and 14 is a sealing member that seals the tail portion of the insulating pipe.

Reference numeral 15 is an air supply pipe connected to the discharge pipe 5, and a gas cylinder 16
The gas generated from the gas is sent into the discharge pipe 5 via the constant pressure valve 17.

In the above configuration, as in the above description, the sample solution is sent through the introduction tube 3 at a flow rate of 101 μ / min, and 1 μm
/ Min is split into the porous member 4, and 100 μ / min is split into the discharge pipe 5. On the other hand, the exhaust pipe 5 is mixed with air (which may be nitrogen gas or the like) having a constant pressure at a flow rate of, for example, about 100 cc / min through the air supply pipe 16, and the air is discharged together with the excess sample solution through the valve 6. It

When a gas having a constant pressure is present in the discharge flow path as described above, for example, even when the delivery flow rate of the liquid chromatograph changes, the pipe pressure at the position of the porous member 4 is kept constant.

That is, in the example of FIG. 5 in which the flow path from the introduction pipe 3 to the discharge pipe 5 and the valve 6 is filled with the sample liquid, the volume of the sample liquid that can exist in the flow passage is determined. If there is such a slight flow rate fluctuation, the fluctuation immediately leads to a large fluctuation in the pipe pressure, whereby the porous member 4
The flow rate of the sample liquid that passes through will also change significantly.

However, in the present invention in which a constant-pressure gas coexists with the sample solution in the discharge channel, the volume of the gas easily changes, so that the volume (quantity) of the sample solution that can be present in the channel is not constant but varies in width. There is. Moreover, since the gas is supplied at a constant pressure, the pressure of the sample solution at the position of the porous member 4 is always maintained at a constant pressure related to the pressure of the gas even if the flow rate changes as described above. become. Therefore, the flow rate of the sample liquid passing through the porous member 4 can be kept constant.

To adjust the flow rate of the sample liquid passing through the porous member 4,
It goes without saying that the pressure of the sample liquid at the position of the porous member may be adjusted by appropriately adjusting the pressure of the gas.

The ionization of the sample liquid introduced into the ionization chamber is not limited to electron impact ionization such as chemical ionization, primary particle beam impact ionization, and laser irradiation ionization, and various ionization methods can be applied.

Further, in the above-mentioned embodiment, the splitter is provided at the end of the introduction pipe 3, that is, the porous member 4, but as shown in FIG. It may be a splitter.

Further, the pressure setting range of the constant pressure valve 17 includes the atmospheric pressure and below. When setting the pressure below atmospheric pressure, as shown in FIG. 3, the discharge pipe after the valve 6 is guided to the waste liquid reservoir 18, and the inside of this waste liquid reservoir is reduced by the vacuum pump 19 to the pressure equal to or lower than the pressure set by the constant pressure valve. Therefore, it is necessary to smoothly discharge the sample liquid and the gas.

Further, in the above embodiment, the constant pressure gas was mixed in the flow path between the splitter and the flow rate adjusting valve, but essentially, the constant pressure gas was supplied to the sample liquid discharge flow path from the splitter (action). It is sufficient if a constant pressure can be applied to the flow path.
For example, as shown in FIG. 4, the constant pressure gas may be introduced directly into the drainage reservoir 18 of the drainage pipe 16 and introduced into the drainage reservoir 18 via the air supply pipe 15. If a structure in which the internal pressure is kept constant by the upper and lower sides of a lid, such as a gas tank, is adopted as this drainage reservoir, the gas cylinder 16 and the constant pressure valve 17 are not necessarily provided.

Furthermore, in the above-described embodiment, the sample solution is introduced into the ion source, which is the supply target, through the porous member having a relatively large flow resistance, but similarly, the sample liquid is introduced through the flow path having the flow resistance. It is needless to say that the present invention can be applied to various devices that introduce liquid into the supply target portion.

[Effect] As described above in detail, according to the present invention, a constant pressure is applied to the flow path for discharging the excess sample solution from the splitter, so that even when a small amount of solution is sent at a large split ratio, the splitter is used. A liquid supply device that can maintain a constant flow rate of the liquid sent from the supply unit to the supply target unit is realized.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of an embodiment in which the present invention is applied to an electron impact ionization (EI) ion source, and FIGS. 2 to 4 are schematic diagrams for explaining other embodiments of the present invention. FIGS. 5A and 5B are schematic diagrams showing the structure of the sample introduction part of the ion source of the type in which the sample solution is introduced into the ionization chamber through the porous member so as to be exuded and ionized. 1: Liquid chromatograph 2: Ionization chamber, 3: Introducing pipe 4: Porous member, 5: Exhaust pipe 6: Flow rate adjusting valve, 15: Air supply pipe 16: Gas cylinder, 17: Constant pressure valve

Claims (2)

[Claims] 1. A splitter is provided in a flow path for transporting a liquid from a high pressure region to a low pressure region, and liquid taken out through the splitter is supplied to the low pressure region via a flow channel having flow channel resistance. In the liquid supply device configured to
A liquid supply device, characterized in that a gas having a constant pressure is supplied to the excess liquid discharge flow path of the splitter to apply a constant pressure to the excess liquid discharge flow path. 2. The liquid supply apparatus according to claim 1, wherein the low pressure region is an ion source of a mass spectrometer.