JPH03223671A - Air bubble mixing detector of liquid chromatography - Google Patents

Abstract

PURPOSE:To enhance operating efficiency by providing a counter counting the length of the output time from an optical detection means at the time of the detection of air bubbles at every unit time and a judging means comparing the count value of the counter with a predetermined value to judge the mixing amount of air bubbles. CONSTITUTION:The signal of a photodetector 4 is sent to a signal counter circuit 5 and a signal measuring circuit 6 and the amount of air bubbles passing through piping 1 is detected by the circuits 5, 6. That is, in this case, the signal counter circuit 5 counts the output of the photodetector 4 at every unit time (sampling time), for example, on the basis of the signal from a timer circuit 8 setting a sampling time and this count value is compared with a preset threshold value to output a signal when the count value exceeds the threshold value. Since the set value of the detected amount of air bubbles can be selected at request in this case, efficient operation is performed.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a liquid chromatography device and a filter bubble akukenda device used therein, and more specifically, to a liquid chromatography device used in the operation of separation 1 analysis. The present invention relates to a bubble detection device used to prevent deterioration in separation performance due to bubbles entering a column, and a liquid chromatography device equipped with the same.

(Prior art) In general, in the operation for separation 1 analysis using liquid chromatography, a separation cylinder (hereinafter referred to as r
A sample is introduced into the column (referred to as column 1) using a pump or a syringe, and then the eluent is sent to the column using a pump to collect the necessary substance in advance. By the way, in this kind of operation, the sample and the solution! III
If air bubbles generated during liquid transfer or along with the liquid being transferred are introduced into the column, there is a problem that the device and the growth performance will be significantly reduced2. In night body chromatography devices, a protection device is often provided for the purpose of preventing the introduction of gas into the column.

Conventional protection devices used to prevent the introduction of air bubbles into such columns include, for example, float type 1 ultrasonic type,
For example, a method of detecting the liquid level (air-liquid interface) in a storage tank of a liquid to be sent to a column using a sensor such as an electric conductivity type, a capacitance type, or a transmission optical type is adopted. In other words, due to so-called "liquid depletion", which is a typical case of air bubbles being introduced into the column, sample and dissolved aI! Since a gas phase may be introduced instead of a liquid, this problem can be solved by detecting the liquid level with the sensor described above and recording this as a danger signal of gas phase contamination, and then using liquid chromatography based on this. This can be avoided by automatically stopping the operation of the equipment, or by using it as a signal to control the operation of related equipment to protect the equipment.

(Problem to be Solved by the Invention) However, in a liquid chromatography device that consists of the above-mentioned column and liquid supply pipes that supply and discharge liquid to and from the column, the introduction of air bubbles into the column is caused by the above-mentioned "liquid shortage". In addition, there are also problems such as the generation of gas phase due to foaming of the sample or mtlJ liquid, and the generation of bubbles and gas particles due to changes in solubility in the liquid due to changes in humidity, reduced pressure due to pump suction, etc. Therefore, conventional methods such as simply monitoring the liquid level in a container or the like may not be able to sufficiently protect the liquid chromatography apparatus.

One way to deal with this problem is to sufficiently degas the sample and eluent to be used in advance by heating, ultrasonication, or the like. However, when such pretreatment is performed, unstable samples and eluents may be degraded, and particularly when protein chambers are used as samples, denaturation such as loss of physiological activity may occur. For these reasons, there are many cases in which preprocessing operations are subject to content or time constraints. Furthermore, when the process is scaled up to an industrial scale, there is also the problem that the processing effort becomes enormous17.

Another possible method is to provide a sensor that detects the presence of air bubbles in the piping upstream of the column, for example.

However, according to the research of the present inventor, simply applying a method using a sensor that detects air bubbles in the middle of piping for the purpose of protecting liquid chromatography equipment only applies when it is originally necessary to protect the equipment. However, it has been found that there is a problem in that the equipment is overprotected, resulting in a decrease in operational efficiency, particularly in the case of a significant decrease in productivity on an industrial scale.

This is because bubbles in the liquid supplied to the column are introduced into the column in a mixed phase with the liquid, but the column system is under pressure, and the higher the pressure, the more the bubbles or gas particles are entrained. Dissolve again. In addition, in such a dissolved state, the separation performance of the column will not deteriorate, and the equipment will continue to operate even when the presence of air bubbles in a range that does not affect the separation performance is detected, that is, even when there is no need to stop it. This is because it would result in the system being stopped.

The present invention was made based on such knowledge, and it is not only possible to simply detect the presence of air bubbles in the middle of piping, but also to detect the presence of air bubbles in a range that does not affect column separation performance. By separately detecting the presence of air bubbles or gas particles in the piping that would reduce the separation performance of the column, liquid chromatography is effective in ensuring high operating efficiency of the equipment without reducing the separation performance of the column. An object of the present invention is to provide a device for detecting air bubbles in a graphics device.

(Means and Effects for Solving the Problems) A feature of the air bubble detection device for a liquid chromatography apparatus according to the present invention to achieve the above-mentioned object is that air bubbles are detected in the piping that supplies liquid to a liquid chromatography column. a detection means that detects the passing of bubble detector No. 18 and outputs it as an electrical signal; and a first detection means that issues an output signal when the number of outputs per unit time from this detection means exceeds a predetermined value. A bubble inclusion determination means, a second bubble inclusion determination means that issues an output signal when the output signal from the detection means continues for a predetermined period of time or more, and output signals from these first and second bubble inclusion determination means. It has a configuration including an OR circuit that operates according to the following.

The detection principle and method of the means for detecting air bubbles passing through the piping are not particularly limited as long as the phase change brought about by the passage of air bubbles can be detected as an electrical, optical, etc. change. However, the bubbles pass through the piping, which is generally relatively thin, separated from the liquid, and therefore, the means for detecting them is generally to pinch a transparent tube section provided in the piping. A non-contact method that detects the passage of bubbles by arranging a light emitting means and a light receiving means, and inputting an optical signal to the light receiving means (or by turning off the normal input) based on changes in the refractive index or transmission amount when the bubble passes. The method using the above method is particularly preferably adopted.

Such optical detection means include, for example, a method in which the emitter itself is a pulse-emission type and the number of pulses received by the receiver is counted, or a method in which the emitter is a continuous-emission type and a counter measures the number of pulses received by the receiver. An example of this method is to count the time length of the bubble detection signal.

As an example of counting the number of continuously received bubble detection signals, a circuit configuration that checks the presence or absence of light reception at every minute sampling time and adds up the number of times the light reception is detected can be exemplified.

Typically, such an optical bubble detection device includes a light-transmitting cylindrical part installed in the middle of piping that supplies liquid to a liquid chromatography column, and a light-transmitting cylindrical part that passes through the light-transmitting cylindrical part from a projector. An optical detection means that detects the passage of a bubble by transmitting or blocking light received by a light receiver and outputs a bubble detection signal, and the length of the output time from the optical detection means when detecting a bubble is defined as unit time. An example of such a structure includes a counter that counts each time, and a determining means that determines the amount of bubbles mixed in by comparing the counted value of the counter with a predetermined value.

Further, it is preferable that the amount of detected bubbles is set so that the determination condition can be changed depending on the operating conditions of the device and the like. Specifically, the column size, eluent, operating pressure, temperature, etc. used in liquid chromatography devices vary, and if the column size differs, the amount of bubbles allowed will inevitably change, and the type of eluent will vary. Another reason is that the solubility of the gas varies depending on its composition, operating pressure, and temperature. Therefore, in response to these cases, it is necessary to be able to set a level at which countermeasures such as stopping the fitting operation of the device due to abnormal inclusion of air bubbles are taken.

Additionally, liquid chromatography operations consist of multiple steps such as equilibration (preparation), sample injection, separation, and washing/regeneration steps, and the eluent used or its composition often differs for each step. Therefore, it is more preferable that the above-mentioned judgment conditions can be set for each process.

On the other hand, with non-contact optical detection means, there is a possibility that indoor light or external light may cause objects other than bubbles to be detected by blocking them.
It is also preferable to output an output as a bubble detection.

By having the above-described configuration, the present invention can substantially measure the amount of gas introduced into the column from the number or size of bubbles passing through the piping per unit time. Regardless of the shape of the gas, it is possible to select and detect cases where there is a large amount of bubbles that cause a decrease in the separation performance of the column, and based on this detection information, the system can prevent the decrease in the separation performance of the liquid chromatography device. It can be used to stop the operation of the device in case of

The air bubble detection device described above is placed upstream of the liquid feeding pump installed in the liquid feeding piping system of a liquid chromatography device, particularly in the middle of the piping system that branches off via a switching valve at the upstream position of the liquid feeding pump. By doing so, a liquid chromatography apparatus can be suitably configured. In other words, when the device is operated to switch to liquid feeding from the other branched piping system after finishing liquid feeding from one branched piping system, the above-mentioned air bubbles may be mixed in the middle of the one piping system. This is because by arranging the detection device, it is possible to automatically determine the switching timing of the liquid feeding switching valve without managing the time and flow rate.

This is for the purpose of preventing air bubbles from entering the column.
As shown in FIG.
If it is placed immediately before the column 20, if abnormal inclusion of air bubbles is detected, it becomes necessary to stop the liquid feed pump 22 and take appropriate measures to remove air bubbles from the piping. However, such operations are particularly complicated in terms of process control and reduce production efficiency when recovering specific substances on an industrial scale. Note that 25 is a recovery device, 26 is a recovery tank, and 27 is a switching valve.

On the other hand, if the air bubble detection device is placed upstream of the switching valve as described above, it becomes possible to perform a series of operations continuously without interrupting the operation of the device.

A liquid chromatography apparatus in which the above-mentioned air bubble detection device is installed in the middle of a piping system that branches off via a switching valve upstream of a liquid feeding pump is used, for example, in order to pass a large amount of eluent through a column. On an industrial scale, when transferring liquid by switching between multiple tanks in sequence, or when transferring the entire volume of sample liquid from the sample liquid tank to the sample liquid tank, automatically transfer the eluent that should continue to flow. It is particularly useful in liquid chromatography devices.

For sample introduction, use a six-way valve, etc. (such as a well-known six-way valve or a liquid injection device described in JP-A-60-149973).
In the case of a liquid chromatography apparatus that uses a six-way valve (hereinafter simply referred to as a "six-way valve") to switch the route in the middle of the liquid delivery channel and thereby introduce the sample liquid into the middle of the liquid delivery piping, the six-way valve It can be installed between the liquid pump and the column, and by installing the air bubble detection device in the middle of the piping that introduces the sample liquid into the sample liquid loop of this six-way valve, the sample in the connected tank will disappear. The separation operation can be automatically and repeatedly controlled until (until air bubbles are detected).

(Example) The present invention will be described below based on embodiments shown in the drawings.

Example 1 FIG. 1 is a diagram showing an outline of Example 1 of the present invention. In the figure, 1 is a pipe that supplies liquid to a column (not shown) of a liquid chromatography device, and there is a pipe in the middle of this pipe. is provided with a part (cell 2) whose tube wall is made of a transparent material,
A light emitter 3 and a light receiver 4 are arranged facing each other on both sides of the cell 2, so that the passage of bubbles can be detected based on the difference in refractive index between the gas phase and the liquid phase. Although a light emitter with a continuous light emitting function is used, a light emitting device with a short pulse light emitting function can also be used. In this case, it is desirable that light emission and light reception be synchronized. In other words, in this example, under normal conditions when only liquid is flowing in the pipe, the light from the light emitter 3 is as shown in Fig. 2(b).
As shown in FIG. 2(a), the light from the emitter 3 is refracted so that it does not enter the light receiver 4. On the other hand, when bubbles pass through the pipe, the light from the emitter 3 is prevented from entering the light receiver 4 as shown in FIG. 2(a). It is set up so that

The signal from the light receiver 4 is sent to a signal counter circuit 5 and a signal measure circuit 6, which detect the amount of bubbles passing through the pipe 1. That is, in the signal counter circuit 5 of this example, a counter circuit (not shown) counts the output of the light receiver 4 for each unit time (sampling time) based on a signal from a timer circuit 8 in which a sampling time is set, for example, and calculates this counted value. By comparing the count value with a preset threshold value, a signal is output when the count value exceeds the threshold value. The counter circuit is automatically reset at each sampling time and sequentially counts the new outputs of the photodetectors 4.

The signal measuring circuit 6 also includes a timer circuit (not shown) that counts the duration of the signal inputted from the light receiver 4, and compares the time counted by this timer circuit with a preset threshold value to determine the counting time. A signal is output when the value exceeds the threshold. Note that the receiver 4
The timer circuit is reset when the signal from is turned off.

7 is an OR circuit (logical sum circuit), which inputs the signals from the signal counter circuit 5 and the signal measure circuit 6;
When at least one of these signals is input manually, an output is generated, and an air bubble detection signal is outputted via an AND circuit 10. In this example, the output time adjuster 9 is used as the other input of the AND circuit IO.
Although the output time length of the signal output from the AND circuit can be adjusted by using the signal from the AND circuit, such an output time adjuster 9 may be omitted.

The air bubble contamination detection signal output from the AND circuit 10 as described above can be used, for example, as a control signal for a control device or related equipment that stops the operation of the liquid chromatography apparatus, or as a signal to issue a warning to an operator, etc. You can also.

Example 2 FIG. 3 shows an example of a liquid chromatography apparatus of the present invention equipped with a bubble detection device.
The upstream side of the liquid sending pump 32 that sends the liquid to
4.34 is shown. In this example, an air bubble pressure detection device 31 is provided in the middle of one of the branched pipes (first in the eluent feeding order).

According to the liquid chromatography apparatus having such a configuration, when abnormal inclusion of air bubbles is detected by the air bubble detection device 31, the switching valve 37 is immediately switched to prevent air bubbles from being introduced into the column 30. Therefore, two molten rI
This has the effect of allowing a large amount of solution M to be sent from the Ii solution tank. Of course, a second tank can also be used as an auxiliary (reserve) means.

Example 3 This example shown in FIG. 4 has substantially the same structure as Example 2 except that one of the eluent tanks is replaced with a sample liquid tank 33.

With such a configuration, it is possible to automatically feed the eluent following the feeding of the sample liquid, and especially in industrial equipment, the amount of the sample liquid may not be constant for each process. In many cases, it is extremely difficult to manage the automatic transition from the end of sample liquid delivery to eluent delivery in such cases.

However, according to the device of this example, the end of sample liquid feeding can be reliably detected by the air bubble detection device 31, and the switching valve 37 can be switched accordingly, thereby automating a process in which the sample liquid volume fluctuates each time. This has the effect that it can be easily performed.

Example 4 This example shown in FIG.
An example is shown in which a six-way valve 43 is provided between the six-way valve 43 and a bubble detection device 41 is provided in the piping between the sample pump 46 and the sample liquid tank 45 for introducing the sample into the sample liquid loop 44 of the six-way valve 43. There is. As the six-way valve 43, a known one can be used as is.

Note that FIG. 5(a) shows the switching state of the six-way valve 43 when introducing the sample liquid into the sample liquid loop 44 in the same device, and FIG. 5(b) shows the liquid feeding path for feeding the sample to the column 40. The state when the sample liquid loop 44 is introduced in the middle is shown.

Such a liquid chromatography apparatus is preferably used when fractionating trace components or performing high-purity fractionation. Since the device can be operated continuously by repeatedly changing the route, there is an effect that the sample liquid can be used effectively and the device can be operated continuously.

(Effects of the Invention) According to the device of the present invention, it is possible to detect the amount of air bubbles (gas particles) passing through the piping that supplies liquid to the column of a liquid chromatography device, and to set the amount of air bubbles to be detected. The values can be selected as desired, so any conditions (
(column size, piping size, type of solution and its composition, etc.), or when the amount introduced exceeds the amount that degrades the separation performance of the liquid chromatography column used, or when air bubbles are observed, but the device does not operate properly. This has the effect of being able to distinguish between cases where there is no substantial problem and operations that are efficient and do not cause deterioration in separation performance.

In addition, it is possible to eliminate the need to stop the equipment when liquid transfer from a sample liquid tank is finished, or when switching between multiple eluent tanks to automatically transfer a large amount of eluent. It has the effect of simplifying process control and achieving high production efficiency when recovering, etc., and the benefits are extremely large, especially when used as a preparative separation device on an industrial scale.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the operation of the liquid chromatograph sensor according to the present invention. FIG. 3 is a flowchart showing the configuration overview of Example 2 of the liquid chromatography apparatus of the present invention, FIG. 4 is a flowchart showing the configuration overview of Example 3, and FIG.
Figures (a) and (b) are flowcharts outlining the configuration of Example 4 when a six-way valve is used, and Figure 6 is a flowchart outlining the configuration of a liquid chromatography device as a comparative example. be. 1: Piping 2: Cell 3; Emitter 4: Receiver 5: Signal counter circuit 6: Signal measure circuit 7 OR circuit sampling timer 9: Output regulator 10, AND circuit and 4 others Figure (a) \ (b) Figure 3 Figure 3

Claims (1)

[Scope of Claims] 1. Detection means for detecting the passage of air bubbles through piping that supplies liquid to a liquid chromatography column and outputting a bubble detection signal as an electrical signal, and a unit from this detection means. a first air bubble inclusion determining means that issues an output signal when the number of outputs per hour exceeds a predetermined value;
a second bubble inclusion determination means that issues an output signal when the output signal from the detection means continues for a predetermined period of time or more;
A bubble detection device for a liquid chromatography apparatus, comprising an OR circuit operated by output signals from the first and second bubble detection means. 2. A translucent cylindrical part is provided in the middle of the piping that supplies liquid to the liquid chromatography column, and the light transmitted from the projector through the translucent cylindrical part and received by the light receiver is transmitted or blocked to eliminate air bubbles. an optical detection means that detects passage and outputs a bubble detection signal; a counter that counts the length of output time from the optical detection means when detecting air bubbles for each unit time; and a count value of this counter. 1. A bubble inclusion detection device for a liquid chromatography apparatus, comprising: determination means for determining the amount of bubbles mixed in by comparing the amount of bubbles with a predetermined value. 3. The air bubble detection device for a liquid chromatography apparatus according to claim 2, wherein the light projector of the optical detection means is of a pulse emission type. 4. The liquid chromatograph according to claim 2, wherein the light emitter of the optical detection means is of a continuous emission type, and the counter integrates the bubble detection signal from the light receiver as a pulse at minute intervals. Air bubble detection device for graphography equipment. 5. A liquid chromatography device, wherein the air bubble detection device according to any one of claims 1 to 3 is disposed upstream of a liquid feeding pump provided in a liquid feeding piping system of the liquid chromatography device. . 6. In claim 5, the air bubble detection device is provided in the middle of the sample liquid side piping and/or the middle of the eluent side piping of the piping system that is branched via the switching valve at the upstream position of the liquid feeding pump. A liquid chromatography device featuring: 7. In claim 5, the air bubble detection device is provided in the middle of each eluent pipe that is branched through a plurality of switching valves at an upstream position of the liquid feeding pump and connected to a plurality of eluent tanks. A liquid chromatography device featuring: