JPH06347305A - Microextraction method and apparatus - Google Patents

Abstract

(57) [Abstract] [Purpose] It is an object of the present invention to provide a technique for realizing measurement of an extremely small amount of liquid and handling of extraction and discharge, and an apparatus having the technique. [Structure] The extractor is one in which the extraction needles 1 and 2 are angled and fixed to a mounting tool 3, and the extraction needle 1 and 2 are attached by attaching the extractor to a liquid sample 5 contained in a sample container 4 and pulling it up. The trace liquid sample 6 is extracted by the surface tension between the two. [Effect] Only a very small amount of liquid can be extracted, discharged and handled, and the loss of the target liquid can be suppressed to a minimum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for precisely measuring the volume of a liquid, extracting, discharging and handling the liquid.

[0002]

2. Description of the Related Art In the prior art, among what is called a chemical volume meter, the main instruments used for precisely measuring the volume of a liquid are a volumetric flask, a burette,
Pipettes, capillaries) pipettes, etc.

Particularly, capillary pipettes have a thickness of 0.2-10.
This is for accurately weighing 0 mm ³ of solution, and a thick capillary tube having an outer diameter of 5 to 6 mm is used or is attached to another thick tube for easy handling. Since the influence of the surface tension is significant, accurate measurement cannot be performed unless the cleanliness of the glass surface and the liquid discharge rate are carefully considered. A piston syringe or the like is used for sucking and discharging the liquid. Mercury is used to measure the capacity,
Although methyl iodide or the like is used, it is necessary to consider the difference in surface tension with the sample solution. Manually or automatically by mechanically operating the pipette, piston syringe,
Extract, drain and handle liquids.

[0004]

With the above-mentioned prior art, it is impossible to measure, extract, discharge and handle a very small amount of liquid. This is because there are problems of precision measurement due to the limit of the minimum inner diameter of the capillary, and problems such as liquid remaining on the inner and outer walls of the capillary during extraction and discharge.

An object of the present invention is to provide a technique for realizing measurement, extraction, discharge and handling of a very small amount of liquid, and an apparatus having the technique.

[0006]

The above object is to prepare a pipette utilizing the surface tension between one or two or more needles, to measure a very small amount of liquid, and to perform extraction, discharge and handling. It is achieved by doing. The liquid amount can be controlled by the difference in the opening angle between the needles, the interval, and the difference in the surface tension depending on the material of the needles. Further, the liquid amount can be controlled and the liquid can be discharged by an external force such as gas pressure, ultrasonic vibration and mechanical vibration.

[0007]

In the microextraction method of the present invention, only an extremely small amount of liquid can be extracted, the amount remaining on the outer wall of the extractor can be reduced even when discharged, and the loss of the target liquid can be minimized. Further, it becomes possible to control the amount of liquid after extraction.

Furthermore, since the structure is simple, it is easy to clean the extractor, and the extractor can be manufactured at low cost. By changing the needle tip of the extractor, the type of target liquid can be changed without cleaning. Since the surface tension differs depending on the material of the needle tip, the liquid amount control range can be changed accordingly.

[0009]

EXAMPLES The present invention will be described in detail below based on examples.

(Embodiment 1) FIG. 1A shows one of the embodiments. The extractor is one in which the extraction needles 1 and 2 are fixed at an angle to the attachment device 3, and the liquid sample 5 contained in the sample container 4 is attached to the extractor and pulled up to extract the space between the extraction needles 1 and 2. A small amount of liquid sample 6 is extracted by surface tension.

The extraction needles 1 and 2 are made of tungsten and have a tip radius of curvature of about 100 to 200 nm and a diameter of 0.05.
A mm needle was used. The actual tungsten needle 23 is shown in FIG. This tungsten needle 23 has a diameter of 0.0
It was obtained by electrolytically polishing a 5 mm tungsten wire in an aqueous NaOH solution.

As a result of using mercury for the liquid sample 5 by using the tungsten needle 23, a trace amount of the liquid sample 6 of 0.01 to 1 μl is extracted, and the angle and interval between the extraction needles 1 and 2 are set. It was possible to discharge by making it larger. Here, the angle θ between the extraction needles 1 and 2 and the interval d
Can be arbitrarily adjusted by the attachment device 3, and the amount of the trace amount liquid sample 6 can be controlled by this adjustment. In this experiment, the angle θ and the distance d were adjusted by the micrometer, but it is not always necessary to use the micrometer.

The shape of the extraction needles 1 and 2 need not be needle-like, and may be, for example, the plate-like one shown in FIG. 1 (c). When the plate-shaped extraction tools 24 and 25 were used, the extraction amount of the liquid sample could be increased as compared with the tungsten needle 23. The number of extraction needles may be one or two or more. In this case, the extraction amount of the liquid sample can be made extremely small with one line, and can be increased with a plurality of lines.

If there is a risk of dropping the extracted trace amount liquid sample by vibration during handling, the number of extraction needles may be increased.

Further, the extraction needle may be made of any material,
Since the surface tension differs depending on the material, select the material according to the target liquid sample and the extraction amount control range. For example, when a Teflon processed needle is used, when attached to the liquid sample 5, the excess liquid sample is unlikely to be adsorbed to the outside of the extraction needles 1 and 2, and the liquid sample 5 can be handled without loss during extraction and discharge. It will be possible.

When it is desired to perform an electrolysis treatment after extracting the trace amount liquid sample 6, the liquid sample could be electrolyzed by applying a positive potential to the extraction needle 1 made of a conductor and a negative potential to 2. .

When it is desired to extract only negative ions or positive ions in the liquid sample, the extraction needles 1 and 2 are made to be a conductor and the surface is made to be an insulator so that the needles 1 and 2 have a positive potential. When a small amount of the liquid sample 6 was extracted by applying a voltage, only negative ions could be extracted. Further, only the positive ions could be extracted by reversing the potentials of the needles 1 and 2. In this case, since the extract was electrically adsorbed on the needle, it did not fall even if vibration was applied during handling.

(Embodiment 2) In Embodiment 1, the amount control and discharge of the extracted trace amount liquid sample 6 are performed by controlling the angle and interval between the needles. However, depending on the sample handled,
It may not be possible to easily control and discharge a very small amount. Therefore, the external force of the air pressure can be used to control and discharge it. FIG. 2 shows one of the examples.

In FIG. 2, the amount of the trace amount liquid sample 6 extracted by sending the compressed air 8 from the nozzle 7 was controlled. By varying the air pressure with the compressed air controller 9, it was possible to precisely control the amount. The same effect was obtained not only by sending out compressed air but also by sucking air from the nozzle 7. In addition, the amount could be controlled by using compressed air when extracting the liquid sample rather than after extracting it. The liquid sample is discharged by increasing the pressure of compressed air. In FIG. 2, the nozzle 7 is inside the needles 1 and 2 of the extractor, but it is also possible to make a flow of compressed air act from the nozzle to the entire extractor. As a result, it was possible to discharge the liquid without leaving an extra liquid sample outside the extraction needles 1 and 2.

For samples that undergo oxidation, nitridation, and other chemical changes when exposed to air,
Instead of air, an inert rare gas such as helium is used so as not to chemically change.

(Embodiment 3) In Embodiment 1, the amount control and discharge of the extracted trace amount liquid sample 6 are performed by controlling the angle and interval between the needles. However, depending on the sample handled,
It may not be possible to easily control and discharge a very small amount. Further, in the second embodiment, since the trace amount liquid sample 6 is discharged by the pressure of the compressed air, the liquid sample may jump out vigorously at the time of discharging and may not be discharged to a predetermined position. Therefore, the external force of ultrasonic waves can be used to control and discharge the ultrasonic waves. FIG. 3 shows one of the examples.

In FIG. 3, the amount of the trace amount liquid sample 6 extracted by controlling the ultrasonic wave 11 from the ultrasonic wave transmitter 10 was controlled. It was possible to precisely control the quantity by changing the intensity and frequency of the ultrasonic wave with the transmitter controller 12. In addition, the amount could be controlled by using ultrasonic waves not only after extracting the liquid sample but also when extracting it. The liquid sample is discharged by increasing the intensity of ultrasonic waves. In FIG. 3, the ultrasonic transmitter 10 is attached to the inside of the needles 1 and 2 of the extractor, but ultrasonic waves may be emitted from the outside of the extractor, for example, from the lateral direction. As a result, the excess liquid sample adsorbed to the outside of the extraction needles 1 and 2 could be almost completely removed.

(Embodiment 4) In Embodiment 1, the amount control and discharge of the extracted trace amount liquid sample 6 are performed by controlling the angle and interval between the needles. However, depending on the sample handled,
It may not be possible to easily control and discharge a very small amount. Further, in the second embodiment, since the trace amount liquid sample 6 is discharged by the pressure of the compressed air, the liquid sample may jump out vigorously at the time of discharging and may not be discharged to a predetermined position. Therefore, the mechanical vibration can be used for the control and discharge. FIG. 4 shows one of the examples.

In FIG. 4, the mechanical vibration mechanism 13 vibrates the entire extractors 1 to 3 to control the amount of the trace amount liquid sample 6 extracted. By varying the intensity and frequency of the mechanical vibration with the controller 14, the quantity control could be precisely performed. In addition, the quantity control was possible even if mechanical vibration was applied when the liquid sample was extracted, not after it was extracted. The liquid sample is discharged by increasing the strength of mechanical vibration. Although the mechanical vibration is applied in the vertical direction in FIG. 4, it may be applied in the horizontal direction.

(Fifth Embodiment) In the first to fourth embodiments, the amount of the extracted trace amount liquid sample 6 is controlled by controlling the angle between the needles, the interval, and the external force. However, precise amount control can also be performed by controlling the insertion depth and speed of the needles 1 and 2 of the extractor into the liquid sample 5 during extraction. FIG. 5 shows one of the examples.

The fifth embodiment is similar to the first embodiment except that the vertical drive mechanism 1 is used.
5, a position control controller 16, an extractor and a liquid sample surface position detector 17 are added and improved. Here, the same improvements as those of Examples 2 to 4 may be used. In FIG. 5, the position detector 17 detects the distance between the extractor and the liquid sample surface, and the position controller 16
Send that signal to. The vertical drive mechanism 15 was driven by the position controller to insert the whole extractors 1 to 3 into the liquid sample 5 and pull up to extract a small amount of the liquid sample 6. By controlling the insertion depth and speed, it was possible to improve the absolute amount accuracy of the trace amount liquid sample in the case of repeated extraction.

(Embodiment 6) In Embodiments 1 to 5, the amount of the extracted trace amount liquid sample 6 is controlled by controlling the angle between the needles, the distance between the needles, and applying an external force, or the needle of the extractor at the time of extraction. This is possible by controlling the insertion depth and speed of the liquid sample 1 and 2 into the liquid sample 5. However, by measuring the weights of the liquid sample 5 and the sample container 4 after extraction, it is possible to improve the absolute amount accuracy of the trace amount liquid sample 6. FIG. 6 shows one of the examples.

FIG. 6 shows an embodiment improved by adding a weighing device 18 and a weighing controller 19 to the fifth embodiment. In FIG. 6, the weights of the liquid sample 5 and the sample container 4 after extraction are measured by the weighing machine 18, and the measured values are measured by the weighing controller 19
And calculate the volume of the trace amount liquid sample 6 extracted from the density of the liquid sample. The signal of the calculated volume is sent to the position control controller 16, and the liquid sample 5 of the needles 1 and 2 of the extractor is sent.
It was possible to improve the absolute amount accuracy of a small amount of liquid sample in the case of repeated extraction by feedback control of the insertion depth and the speed.

(Embodiment 7) In Embodiments 1 to 6, the handling of the extracted trace amount liquid sample 6 is carried out manually, but by incorporating the entire extractor including the amount control mechanism into the automatic transfer device, It is possible to improve the work efficiency of handling a small amount of liquid by fully extracting, discharging and handling. FIG. 7 shows one of the examples.

FIG. 7 shows an improvement of the fifth embodiment by adding an automatic moving mechanism 20 and a receiving sample container 21. here,
It is also possible to add the same improvements to the sixth embodiment. Figure 7
At, the position detector 17 detects the distance between the extractor and the surface of the liquid sample, and sends a signal to the position controller 16. The vertical drive mechanism 15 is driven by the position controller 16 in response to the signal, and the needles 1 and 2 of the extractor are inserted into the liquid sample 5 and pulled up to bring the minute amount of liquid sample 6 into consideration.
Was extracted. The extracted minute amount of liquid sample 6 was moved to the receiving sample container 21 by the automatic movement mechanism 20 controlled by the position controller 16, and the minute amount of the liquid sample was discharged, whereby the handling could be automated.

Further, by measuring the weights of the receiving sample container 21 and the extracted trace amount liquid sample 22 in the same manner as in Example 6, it was possible to control a very small amount. By arranging and handling a plurality of extractors and sample containers, it is possible to construct an automated system capable of simultaneously handling many kinds of extremely small amounts of liquid samples.

[0032]

According to the present invention, only a trace amount of liquid can be extracted, discharged and handled, and the loss of the target liquid can be minimized. Further, the measurement and control of the liquid amount after extraction becomes easy. Furthermore, since the structure is simple, it is easy to clean the extractor and the extractor can be manufactured at low cost. By exchanging the needle tip of the extractor, the type of target liquid can be changed without cleaning, and the surface tension changes due to the difference in the needle tip material. It can handle a very small amount.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing a second embodiment of the present invention.

FIG. 3 is a block diagram showing a third embodiment of the present invention.

FIG. 4 is a block diagram showing a fourth embodiment of the present invention.

FIG. 5 is a block diagram showing a fifth embodiment of the present invention.

FIG. 6 is a block diagram showing a sixth embodiment of the present invention.

FIG. 7 is a block diagram showing a seventh embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Extraction needle, 2 ... Extraction needle, 3 ... Attachment device, 4 ... Sample container, 5 ... Liquid sample, 6 ... Trace liquid sample, 7 ... Nozzle, 8 ... Compressed air, 9 ... Compressed air controller, 10 ...
Ultrasonic wave transmitter, 11 ... Ultrasonic wave, 12 ... Oscillator controller, 13 ... Mechanical vibration mechanism, 14 ... Controller, 15
... Vertical drive mechanism, 16 ... Position control controller, 17 ...
Position detector for liquid sample surface of extractor, 18 ... Weigher, 19 ... Weighing controller, 20 ... Automatic movement mechanism, 2
DESCRIPTION OF SYMBOLS 1 ... Acceptable sample container, 22 ... Extraction trace amount liquid sample, 23 ... Tungsten needle, 24 ... Plate extraction device, 25 ... Plate extraction device.

Claims (7)

[Claims] 1. A trace amount of liquid is extracted by utilizing the surface tension between one or more needle-shaped extractors, and the shape of the extractor,
A microextraction method characterized by controlling, measuring, or discharging a microvolume of an extracted microvolume based on a difference in surface tension due to a difference in geometrical arrangement and material. 2. The angle and spacing between two or more needles are adjusted to control the amount of trace liquid extraction.
The described microextraction method. 3. A drive mechanism for detecting the positions of the extractor and the surface of the liquid sample, and controlling the insertion depth and speed of the extractor for controlling the amount of the trace amount of the liquid extracted. Micro extraction method. 4. The microextraction method according to claim 3, wherein gas pressure is used for controlling the extraction amount of the trace amount liquid and discharging the extract. 5. A mechanical impact force is used for controlling the extraction amount of a trace amount of liquid and discharging the extract.
The described microextraction method. 6. The microextraction method according to claim 3, wherein ultrasonic vibration is used for controlling the extraction amount of the trace amount liquid and discharging the extract. 7. One or more needle-shaped extractors of a predetermined shape and material for extracting a trace amount of liquid at the tip thereof by utilizing surface tension, and means for controlling the geometrical arrangement of the extractors. And a microextraction device comprising a drive mechanism capable of moving the extractor in a three-dimensional direction.