JPS6242708A - Defoamer - Google Patents

Abstract

PURPOSE:To defoam in an extremely short time, to continuously defoam and to surely defoam even a small amt. of liq. by providing a reduced-pressure chamber above a defoaming chamber furnished with the inlet and the outlet of liq. through a gas permeable membrane. CONSTITUTION:A defoaming chamber 2 is formed at a part of a liq. passage and a reduced-pressure chamber 3 is provided along the upper part of the liq. passage through a gas permeable membrane 4. An inlet 10 and an outlet 11 are connected to the defoaming chamber 2 and a discharge port 12 is protruded from the reduced-pressure chamber 3. When the defoamer thus constituted is incorporated in the passage of the eluate 14 sent by a feed pump 15, the air bubbles 16 mixed into the eluate 14 or generated are floated in the defoaming chamber 2, passed through the gas permeable membrane 4, sucked by the reduced-pressure chamber 3 and discharged from the discharge port 12 to the outside of the system. The eluate 14 contg. no air bubbles is continuously sent into a column 17 in this way.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an apparatus for removing air bubbles contained in a liquid, and in particular to a device for removing air bubbles contained in a liquid, and particularly for removing an eluent in liquid chromatography analysis or a liquid sample to be subjected to optical analysis using a tube or a device. It relates to a device that uses a gas permeable membrane to effectively remove liquid while it is being sent through a pipe to a detection unit such as a column or cell.

[Prior art and its problems]

When analyzing liquid samples using columns or flow cells, the presence of air bubbles in the eluent or liquid sample is extremely troublesome. Particularly in the case of liquid chromatography analysis, if air bubbles enter the column, the contact between the stationary phase and the mobile phase is broken, making normal analysis impossible, and the oxygen in the air bubbles can cause deterioration or oxidative decomposition of the stationary phase and sample. This may worsen the raising characteristics and resolution.
Eventually it becomes unusable. It also prevents normal liquid delivery by the pump. On the other hand, in colorimetric analysis and scattering power measurement using a flow cell, bubbles prevent normal transmission and scattering of light and cause noise.

However, in these devices, it is inevitable that air bubbles will be mixed in at the eluent/sample liquid suction points, tubes, pipes, and other connection points, and that dissolved gases will become bubbles due to changes in temperature and internal pressure. Further, most sample liquids for optical measurement are obtained by stirring and mixing a test liquid and a reagent, but a large amount of air is mixed in with the stirring.

In the case of sample liquids that are continuously and automatically analyzed using eluents and flow cells in liquid chromatography analysis,
Air bubbles mixed into these or generated inside are sure to migrate to the detection section.

Therefore, conventionally, bubbles in the eluent used in liquid chromatography analysis have been removed by various means such as heating, reduced pressure, or ultrasonic treatment. However, all of these devices require a lot of manual labor, and are problematic in terms of operability and cost. In addition, these processes are usually batch-type since they are degassed in an open environment, and there is a risk that air bubbles may be mixed in again when the eluent is sucked. Moreover, organic eluents have the risk of igniting when heated, and those containing solutes such as buffers have the problem of deterioration and concentration changes due to evaporation of the solvent.

On the other hand, when measuring liquid samples optically, there are problems similar to those mentioned above, and when a large number of small samples (often 1mt or less to several meters) are continuously measured, such as in clinical tests, conventional Defoaming treatment is difficult or extremely time-consuming and impractical.

Therefore, in this case, measurement is performed without removing air bubbles, and if the obtained signal exceeds the reference value, the signal is considered to be the effect of air bubbles or dust, and the signal is ignored and measured. ), various measures have been taken, such as receiving such a signal and placing it in a non-measuring state using a switch circuit (for example, Japanese Patent Publication No. 58-2365). but,
This method requires an extra circuit for signal processing, which is costly, and the reliability of the measurement results inevitably becomes low.

Furthermore, JP-A-57-165007 discloses a technique in which a liquid is placed in a tubular or other synthetic resin container and the synthetic resin container is exposed to a reduced pressure atmosphere to degas the dissolved gas in the liquid. has been done. This utilizes the gas permeability of synthetic resin, but due to its nature, large objects such as air bubbles cannot be removed. Furthermore, in order to effectively remove dissolved gas, a long tube of 10 to 20 m is required, making the device large and expensive. Therefore, it is not suitable for optical analysis, especially when handling small amounts of sample liquid.
Treatment of the eluent is also impractical as it requires a separate defoaming device.

[Object of the present invention]

The present invention has been made in view of the above, and an object of the present invention is to provide a small and lightweight air bubble removal device capable of continuous defoaming so as to be incorporated into an automatic liquid analyzer including a column or a flow cell. Another object of the present invention is to provide a bubble removal device that has a simple structure, can be obtained at low cost, and can reliably defoam a small amount of sample liquid with a simple operation.

[Means to achieve the purpose]

These objectives are achieved by utilizing the property of air bubbles rising in a liquid, and by providing a decompression chamber through a gas permeable membrane above a defoaming chamber equipped with a liquid inlet and an outlet.

The upper surface of the eluent and sample liquid sent from the inlet is in contact with the gas permeable membrane, and the air bubbles rise inside the defoaming chamber, pass through the gas permeable membrane, move to the decompression chamber, and are pumped out of the system. be discharged. This bubble migration is caused by the viscosity of the eluent or sample solution.

Although it depends on the size of the bubbles, etc., the liquid used usually has a low viscosity, so the process can be carried out in an extremely short time. Therefore, it is sufficient that the size of the a-presentation is about the same as that of a liquid path, which is several to several tens of cm+.

In addition, in order to effectively remove the dissolved gas by creating bubbles and expanding the bubbles, the eluent or liquid sample should be heated at 40 to 50 ml.
A heating device that raises the temperature to below about 0° C. or a device that applies vibration may be provided in the defoaming chamber or near the inlet.

Next, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1(a) is a schematic diagram of a liquid chromatograph analyzer incorporating a longitudinal section showing an example of the bubble removing device of the present invention, and FIG. 1(b) is a partial perspective view of the bubble removing device in cross section. It is.

In this bubble removal device (1), a defoaming chamber (2) constitutes a part of the liquid path, and a decompression chamber (3) is provided along the upper part of the liquid path through a gas permeable membrane (4). There is. Then, Ii1 that matches when superimposed on the two plate-shaped bodies (5) and (6)
Grooves (7)...(8)... are carved, and the gas permeable membrane (
4) and are integrated with screws (9), other fasteners, adhesives, etc., and the vertical grooves (7) on the lower side...
the degassing chamber (2), the upper vertical groove (8)... the decompression chamber (3)
). In addition, an inlet (l) and an outlet (11) are provided at the upper and lower ends of the defoaming chamber (2), respectively, and the decompression chamber (3) is provided with an inlet (l) and an outlet (11), respectively.
) are provided with exhaust ports (12) protruding from them, to which tubes (13) and pipes are connected, respectively.

The size of the defoaming chamber (2) is from 1 to several liters depending on the thickness of the tube (13), etc. It should be about IIIR. Also, the defoaming chamber (
2) The length depends on the liquid flow rate, amount of liquid fed, viscosity, etc., but it should be about several to tens of Cl11, and the pressure in the decompression chamber (3) also depends on the liquid flow rate, etc., but it is 100 to 500 neml. [
About g is sufficient to achieve the purpose.

The material of the plate-like body may be metal, but it is preferable to use customs-clearable plastic because bubbles and their removal can be observed. Furthermore,
For mass production, it is best to integrally mold the vertical grooves, inlets, and exhaust ports with resin.

On the other hand, the gas permeable membrane (4) has a fine pore size (for example, 0
．． A porous plastic film having continuous pores (about 2 to several microns) is used. This film allows gas to pass through because of its continuous pores, but those made of hydrophobic resins such as tetrafluoroethylene and polyethylene do not allow water to pass through. Furthermore, polyvinyl alcohol-based hydrophilic resins do not allow organic solvents to pass through them, so it is preferable to use a preferable type of film depending on the solvent of the molten liquid or sample liquid.

Note that the higher the porosity of the film and the thinner the film thickness, the better the foaming property is, but especially when it comes to thickness, it is best to select the optimal one in consideration of strength. Currently commercially available products have a porosity of 25
~95%, with a thickness of about 0.1 to 0.5 mm.

However, if the bubble removing device (1) is installed in the middle of feeding the eluent (I4) with the liquid feeding pump (15) as shown in Figure 1 (al), bubbles may be mixed in or generated in the eluent (I4). The bubbles (I6) float up in the degassing chamber (2), are drawn into the decompression chamber (3) through the gas permeable membrane (4), and are sent to the exhaust port (
12) is discharged outside the diameter. The bubble-free eluent (14) is thus continuously fed into the column (17).

In the above example, the vertical grooves (7) were provided at a uniform depth, but they were made to become shallower on the outlet (11) side as shown in Figure 2 (a), so that small air bubbles could penetrate the gas permeable membrane ( 4) can be easily accessed. At this time, in order to suppress the increase in flow velocity in the shallow part, it is recommended to widen the groove width in this part as shown in Fig. 2 (b). In order to promote bubble formation of the dissolved gas and expansion of the bubbles (16), a heater (I8) is provided on the inlet port (10) side as shown in Fig. 3.
14) may be heated to a level (approximately 40 to 50° C. or less) that does not cause any inconvenience, or vibration may be applied to the defoaming chamber (2) etc. using a vibrator (19) or the like. When the defoaming chamber (2) is made of metal, it may be heated either by heating itself or by heating the eluent container. In addition, a radiator (27) and a cooler for lowering the heated eluent to a desired temperature should be installed at the outlet (I).
If provided after 1), it is preferable from the viewpoint of preventing the remaining dissolved gas from becoming bubbles and protecting the column.

Furthermore, the gas permeable membrane (4) is made higher on the inlet (10) side and lower on the outlet (11) side, and the inlet (10) is made lower on the outlet (11) side.
1) By installing it at a higher position, air bubbles (IG)
can be effectively prevented from passing through the defoaming chamber (2) in contact with the gas permeable membrane (4). As shown in FIG. 3, the same effect can be obtained even if the entire bubble removing device (1) is tilted so that it is higher on the inlet (10) side.

Next, FIGS. 4 and 5 show another example of a bubble removing device (1) configured such that the separate chamber-like defoaming chamber (2) forms a part of a liquid path. Figure 4 shows that a part of the upper side of the pipe (2) is cut out, the part is covered with a gas permeable membrane (4), and the sealing body (21) that forms a reduced pressure chamber (3) on the upper part is airtight. This bubble remover (1) has the advantage that it can be installed by simply inserting the pipe (20) into the middle of the tube (I3) and does not take up much space. The device (11) is also a pipe (20) with a gas permeable membrane (4) in its interior, and the gas permeable membrane (4) is supported by a frame (22) and inserted into the pipe (20).
23) and (23) are fitted and fixed.

In the above, the degassing chamber (2) forms part of the liquid path and the eluent (14
Although the air bubbles in the degassing chamber (2) are a liquid reservoir having a larger capacity than the liquid path as shown in FIG. 6, the same effect of removing air bubbles is obtained. In this case, the inlet (10) is on the upper side of the defoaming chamber (2).

The outlet (11) needs to be provided on the lower side. In this way, the eluent (+ air bubbles (16) in the ship) sent into the degassing chamber (2) from the inlet (10) immediately rises in the degassing chamber (2) and passes through the gas permeable membrane ( 4), the eluent (14) without air bubbles (16) is sent out from the outlet (+1).
1 has the advantage that it is easy to make and can be obtained at low cost by simply sandwiching the gas permeable membrane (4) between a container serving as a defoaming chamber (2) and a lid serving as a decompression chamber (3). However, the liquid sent to the defoaming chamber (2) does not necessarily flow out in the order in which it flows in.
/8 Suitable for defoaming when the same type of liquid is continuously pumped, such as syneresis.

FIG. 7 shows an example in which the bubble removing device (1) shown in FIG. 1 is incorporated into a colorimetric analysis device using a flow cell (2-layer).

In this case, since a large number (one in the figure) of liquid samples (25) are alternately suctioned with the cleaning liquid (26) and sent to the flow cell (24), air bubbles (16) are particularly likely to be sucked in during suction. Furthermore, as described above, since there are many bubbles and dissolved gases in the liquid sample (24), there is a high risk of bubble generation. By incorporating a bubble removing device (1) immediately before the liquid sending pump (15), the sample liquid from which these air bubbles (1G) have been removed is sent to the liquid sending pump (15), thereby preventing pump troubles. Measurement errors due to air bubbles are completely prevented.

〔effect〕

As described above in detail, the bubble removal device of the present invention includes a degassing chamber provided with a liquid inlet and an outlet, and a decompression chamber provided through a gas permeable membrane in the upper part of the degassing chamber, which is provided with an exhaust pump or a vacuum. It is equipped with an exhaust port connected to a pump. and,
The bubbles in the eluent or liquid sample that are continuously fed into the bubble-forming chamber are raised, brought into contact with a gas permeable membrane, and are sucked into a vacuum chamber and discharged out of the system.

Therefore, since a small and lightweight air bubble removal device is obtained, it does not take up much space even when incorporated into liquid chromatography analysis, and the entire device can be made more compact. In addition, since it is easy to degas a small amount of liquid sample, it can be incorporated into small automatic colorimetric analyzers and scattering photometers, which were rarely equipped with air bubble removal devices in the past, contributing to improving the accuracy of optical measurements. be able to. Moreover, it has the advantage of being extremely simple in structure, free from failure, and inexpensive.

[Brief explanation of the drawing]

Figure 1 (fat) is a schematic diagram of a liquid chromatograph analyzer incorporating a vertical section showing an example of the bubble removal device according to the present invention, and Figure 1 (g) is a schematic diagram of a liquid chromatography analyzer incorporating a vertical section showing an example of the bubble removal device according to the present invention. FIG. 2 is a cross-sectional partial perspective view, and FIG. 2 shows a modification of the vertical grooves constituting the defoaming chamber.A) is a sectional view, FIG. 3B is a plan view, and FIG. A sectional view showing a modified example, FIG. 4 shows another example of the bubble removing device.a
) is an exploded perspective view, (b) is a cross-sectional view, FIGS. 5 and 6 are further different examples, and FIG. 5 is a perspective view, FIG. 6 is a sectional view, and FIG. FIG. 2 is a block diagram of the colorimetric analyzer installed. l...Bubble removal device 2...Degassing chamber 3...Decompression chamber 4...Gas permeable membrane 10...Inflow port 11. ... Outlet port 12 ... Exhaust port 13 ... Tube 14 ... Eluent 15 ... Liquid pump 16 ... Bubbles 17...Column 20...Pipe 24...Flow cell 25...Liquid sample 26...Washing liquid -1" Figure 1 (b) Figure 2 (a)

Claims (1)

[Claims] 1. A decompression chamber is provided in the upper part of a degassing chamber equipped with a liquid inlet and an outlet through a gas permeable membrane, and an exhaust pump connected to an exhaust pump or a vacuum pump is provided in the decompression chamber. Air bubble removal device with a port. 2. The bubble removal device according to claim 1, wherein the bubble removal chamber constitutes a part of the liquid path. 3. A patent in which two plate-shaped bodies with grooves cut into them are stacked one on top of the other with a gas permeable membrane in between, and the upper groove is used as a decompression chamber and the lower groove is used as a degassing chamber. A bubble removing device according to claim 1. 4. A patent claim in which a portion of a pipe or tube with a part of the upper surface cut out is used as a defoaming chamber, and a sealing body that forms a decompression chamber is fixed to the upper part of the opened portion via a gas permeable membrane. The air bubble removal device according to item 1. 5. The air bubble removal device according to claim 1, wherein the gas permeable membrane has an inlet side elevated, and the inlet is disposed at a higher position than the outlet. 6. The air bubble removal device according to claim 1, wherein the defoaming chamber is composed of a liquid reservoir having a larger capacity than the liquid path, and has an inlet at its upper side and an outlet at its lower side. .