JPS6353499B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for measuring electrokinetic phenomena such as electrophoresis and electroosmosis.

In other words, when an electric field is applied along the solid-liquid interface or the liquid-liquid interface, ions in the diffusion double layer move, and the solvent is carried along with this, and the electroosmotic phenomenon is measured by measuring the fluidity of the liquid. , or the measurement of electrophoretic phenomena, which measures the speed at which colloidal particles move in an electric field (mobility).

For example, as a measuring device for the above-mentioned electrokinetic phenomenon,
Electrophoretic measurement devices that observe the movement of colloidal charged particles are well known in the field of dealing with microscopic surface-charged substances.

The electrophoresis device described above has a function of generating an electric field by passing a direct current through a measurement cell, and measuring the speed at which particles move according to the electric field to calculate the charge of the particles. The basic operating procedure is as follows.

1. Introduce the sample specimen into the measurement cell.

2. Wait until the fluctuations in the sample particles in the measurement cell become stable, observe the sample using a microscope, and determine the particles to be measured.

3 Apply direct current to start particle movement.

4 After the application, the particle mobility, that is, the distance traveled per unit time, is measured after the particle flow reaches a steady state.

5. After the measurement is completed, reverse the polarity of the DC current and perform the same operations as in Sections 3 and 4 to measure the mobility of particles in the opposite direction.

6 The average of the mobilities measured in Sections 4 and 5 is taken as the one-time mobility of the particle.

Hereinafter, the operations in sections 2 to 6 are repeated several dozen to several hundred times, and the average value is taken as the average mobility of the particles of the sample specimen.

The electrophoretic mobility determined by measurement using this electrophoresis device is expressed as the mobility of each particle per electric field strength (microns/second per volt/centimeter).

The mobility of particles due to electrophoresis is highly temperature dependent, so in order to obtain accurate information during measurement, it is necessary to pay sufficient attention to the management of the measurement temperature, which is the most important issue.

Generally, in order to keep the temperature inside the measurement cell constant,
A method is adopted in which a medium is circulated outside the measurement cell and the temperature of the medium is kept constant. However, with this method, it is not possible to quickly respond to the heat generation of the specimen sample in the measurement cell due to the direct current for measurement, and the above problem still cannot be solved.

By the way, the time it takes for the flow of particles to stabilize in the fourth term is approximately 0.1 to 0.2 seconds. However, the temperature of the sample in the measurement cell rises due to the Joule heat generated by supplying the DC current for measurement, and the time required to stabilize this temperature varies depending on the structure of the cell, but generally it takes about 10 to 30 minutes. Several hundred seconds. Therefore, even though the actual mobility measurement time is 1 to 3 seconds per measurement, the temperature is
If you try to start measurement after it has stabilized, it will take tens to hundreds of seconds each time.
It costs a lot of time and labor.

In addition, while waiting for the temperature to stabilize while a direct current is flowing for measurement, the particles to be measured continue to move in one direction. For example, in electrophoresis measurement using a microscope, most particles are visible It has been impossible to perform highly accurate measurements at a constant temperature because the particles may move in one direction.

Therefore, in the measurement of electrokinetic phenomena, it is a major challenge to obtain highly accurate measured values in a short time and under constant temperature conditions.

In order to solve the above problems, the present invention supplies an AC electric field to the sample specimen in the measurement cell and heats it, thereby maintaining the particles at the same temperature as when applying a DC electric field while keeping the particles in a stopped state in observation. This was developed with the focus on the ability to maintain the measurement accuracy, and the purpose is to improve measurement accuracy and shorten measurement time.

Before supplying the measurement DC electric field to the sample specimen, the present invention reduces the AC power consumed in the sample specimen to the same degree as the power consumed in the sample specimen when the measurement DC electric field is supplied. A method for measuring an electrokinetic phenomenon characterized by supplying an electric field to a sample specimen, and an output selection circuit for selecting either a DC power supply or an AC power supply as a power supply device for applying an electric field to the sample specimen. Provided is an electrokinetic phenomenon measuring device comprising:

That is, when measuring the mobility of particles, for example, the present invention provides that when the DC current for electrophoresis measurement is not being supplied to the sample specimen, that is, between measurements, the DC current for measurement is not supplied to the sample in the measurement cell. By continuing to supply an alternating current that consumes the same amount of power in the sample as the consumed power, it is possible to maintain the temperature of the sample in the same state as during measurement.

By the way, for the AC power used in the electrophoresis measurement of the present invention, it is preferable to use a frequency at which the movement of the particles can be considered to be in a stopped state, from the viewpoint of ease of determining the particles to be measured, and usually 10 cycles or more is suitable. It is.

Next, regarding the power supply device used in the present invention, the first
This will be explained with reference to the block diagram shown in FIG. The output of the rectangular wave emitted by the rectangular wave oscillator A is adjusted by the power controller B,
Furthermore, according to the instructions of the output selection circuit C connected next, it is determined whether the current is converted to direct current or remains as alternating current through the rectifier circuit D, and an electric field is supplied to the load E (sample specimen). It is configured as follows.

This square wave oscillator can be replaced by a commercial AC power source.

Alternatively, as shown in Fig. 2, instead of the oscillator A in Fig. 1, it is composed of two DC power supplies A _{1 and} AC power supplies A ₂ , each passing through output adjustment circuits B ₁ and B ₂ and connected to an output selection circuit. It may be connected to C.

By using the measuring method and apparatus of the present invention, mobility is measured under a constant temperature, so there is no error caused by temperature changes, and measurement accuracy can be greatly improved.

Furthermore, although repeated measurements are usually performed,
In this case as well, it is sufficient to repeat the operation of determining the particle to be measured while applying alternating current, immediately switching to direct current, and measuring the mobility of the particle.
Unlike conventional devices, no time is required for temperature stabilization, and the measurement time can be greatly shortened.
Next, an embodiment of an electrophoresis measuring device using a microscope based on the present invention will be described.

As shown in FIG. 3, this electrophoresis measuring device is placed in a thermostatic chamber 1, and has a U-shaped glass tube 2 forming a migration chamber, and a 50 mm
a pair of electrodes 3 placed opposite each other with an interval of
3', and a power source 7 that supplies current to these electrodes.

The U-shaped glass tube 2 is a U-shaped tube with an inner diameter of 2 mm filled with a sample specimen 21, and a tube with an outer diameter of 0.25 mm in the center thereof is covered with a polyethylene tube.
A mm sheathed thermocouple 32 is installed, and a temperature indicator 33 monitors the temperature inside the U-shaped glass tube.

The power source 7 includes a 10 mmA DC constant current power source 71 for applying an electric field to the sample to cause electrophoresis, and a variable transformer 73 connected to a commercial frequency AC power source 72 and equipped with an AC voltmeter 74 for output measurement. are connected in parallel via an output conversion circuit 17 to supply power to the electrodes 3 and 3'.

The output switching circuit 17 is connected to a DC positive polarity relay switch 18 which is connected so that when closed, a DC positive polarity voltage is applied to the current-carrying electrodes 3, 3', and conversely, when it is closed, a DC negative polarity voltage is applied. The circuit consists of a direct current negative polarity relay switch 19 which is connected so that the voltage is normally applied to the electrode, and when both are open, the circuit is connected to an alternating current power source 72.

On the other hand, the constant temperature bath 1 has a temperature control device 4 and a heater 15.
The temperature is set at 20℃±0.1℃.

Next, Experimental Example 1 of measurement using this electrophoresis measuring device will be described.

First, U injected with physiological saline as a sample.
A letter-shaped glass tube 2 is placed in a constant temperature bath 1. Next, the AC power supply 72 is turned on, and while the output is adjusted by the variable transformer 73 so that the value on the voltmeter 74 becomes 108V, the current-carrying electrodes 3, 3'
supplies alternating current to the (At this time, the DC positive polarity relay switch 18 and the DC negative polarity relay switch 19 are kept in the OFF state.) In this way, when the indicated value of the temperature indicator 33 becomes constant and stable, the DC Push the positive polarity relay switch 18 to turn it on and switch the supplied current from alternating current to direct current.

At this time, according to the indicated value of the temperature indicator 33, the temperature inside the U-shaped glass tube 2 changes by 0.1° C. or less when switching from alternating current to direct current.

Incidentally, when direct current is supplied to the current-carrying electrode only during measurement as in the conventional case, the temperature within the U-shaped glass tube changes over time as shown in FIG. 4. In FIG. 4, the vertical axis represents temperature T (° C.), and the horizontal axis represents time t (sec).

Referring to FIG. 4, it is proved that by using the apparatus and method of the present invention for measurement, it is possible to perform measurements under constant temperature conditions, and the measurement accuracy is greatly improved. be done.

When measuring the actual mobility of particles, the following operations are performed. Determine the particles to be measured when AC current is supplied when the particles are in a stopped state for observation, and when the temperature inside the sample becomes sufficiently stable, turn on the DC positive polarity relay switch 18 and measure the speed at which the particles move. do. Next, the direct current negative polarity relay switch 19 is turned on, the velocity of the particles moving in the opposite direction is measured, and the average value of the velocity in both the positive and negative directions is taken as the mobility of one particle.

Then, repeat measurements several tens to hundreds of times in the positive and negative directions.
The average value is considered the mobility.

Furthermore, an electrophoresis measuring device and a measuring method according to a second embodiment of the present invention will be described with reference to FIGS. 5 and 6.

This electrophoresis measuring device includes a rectangular measuring cell 20 with a thickness of 0.7 mm and a height of 7 mm having a cooling water circulation tank 10 on the outside, energized electrodes 3 and 3' set at both ends of the cell, and power supplied to these. A power supply device 8 that performs
0.

The circulation tank 10 is set at 20° C.±0.1° C. by the temperature controller 4 and the heater 15.

The cell 20 is filled with culture solution Eagle, which is a sample specimen, in which sheep red blood cells are suspended.
Further, voltage measuring electrodes 12, 12' are installed inside the current-carrying electrodes 3, 3', and voltage can be measured by a DC voltmeter 45 connected thereto. Further, as shown in FIG. 6, the power supply device 80 includes a rectangular wave oscillator 81, an amplifier 82 for amplifying the rectangular wave signal from the oscillator 81, and an amplifier 82.
A pulse transformer 83 that boosts the rectangular wave voltage from
, a rectifier group 84 that rectifies the AC rectangular wave power from the transformer 83, and a control circuit 85, and the rectifier group 84 has diodes 86 to 89. The control circuit 85 includes a relay switch 90 for direct current positive polarity instruction, a relay switch 91 for direct current negative polarity instruction, and a relay 93 having a normally closed contact 92;
It has a relay 96 having normally open contacts 94 and 95, and a relay 100 having normally closed contacts 97 and 98 and a normally open contact 99.
A voltage from the AC power supply 101 is applied to 00.

Relay switches 90, 91 have normally open contacts 102, 103 and 104, 105, respectively, and relays 93, 96, 10 are connected to AC power supply 101.
It is configured to control the current supplied to zero.

Output terminals 107 and 108 in the power supply device 80
is connected to the current-carrying electrodes 3 and 3', but this output terminal 108 is directly taken out from the middle point of the secondary winding of the transformer 83, and the output terminal 107 is connected to the control circuit. connected to the output. The amplification degree of the amplifier 82 can be arbitrarily adjusted from the outside.

When relay switches 90 and 91 are not activated, none of relays 93, 96, and 100 are energized, so no current flows through diodes 88 and 89, and alternating current flows alternately through diodes 86 and 87, resulting in output An AC voltage corresponding to a rectangular wave signal generated from the oscillator 81 is output to the terminals 107 and 108, and an AC voltage is applied to the current-carrying electrodes 3 and 3'.

When the DC positive polarity relay switch 90 is activated by a sequence circuit (not shown), the contact 10
2 and 103 are turned on, relays 93 and 96 are energized, contact 92 is turned off, and contacts 94 and 95 are turned on, so currents of the same polarity alternately flow through diodes 87 and 89 to output terminals 107 and 108. , a DC voltage is output, and a DC positive polarity voltage is applied to the energizing voltages 3, 3'.

Conversely, when DC negative polarity relay switch 91 is activated by a sequence circuit (not shown), contacts 104 and 105 turn ON, and relays 96 and 10
0 is excited, contacts 97 and 98 are OFF, 94,
95 and 99 are turned on, currents of the same polarity alternately flow through diodes 86 and 88 in the opposite direction to that in the above case, and a DC voltage is output to output terminals 107 and 108, and current is applied to current-carrying electrodes 3 and 3'. A negative DC voltage is applied.

The operation of electrophoresis measurement using such a measuring device is performed in the same manner as described in the first embodiment, but a sequence circuit (not shown) controls the positive polarity relay switch 90 and the negative polarity relay switch. 91 operating voltage is supplied, and AC and DC (positive polarity, negative polarity) operations proceed.

When using the above power supply device, the temperature change when switching between AC and DC was less than 0.1°C, and the voltage fluctuation was less than 0.5V. By the way, if you use a conventional power supply and apply a 10mA DC current only during measurement, the
The voltage that was 71.5V became 70V, and the temperature change was as shown in Figure 7. In FIG. 7, the vertical axis is temperature T (° C.), and the horizontal axis is time t (sec).

As is clear from these measurement results, using such an apparatus and the measurement method of the present invention, it is possible to perform measurements with very high precision, and also in a short period of time without wasting time in stabilizing the temperature. Measurements can be made with

In the examples, only electrophoresis measurements using a microscope have been described, but it goes without saying that the present invention is not limited to this and can also be applied to electrophoresis measurements using a detector Doppler method or the like, or to measurements of electroosmotic phenomena.

As described above, the electrokinetic phenomenon measuring method and apparatus of the present invention can obtain highly accurate measured values without being affected by Joule heat or the like caused by the supplied current.

[Brief explanation of the drawing]

1 and 2 are block diagrams showing a power supply device of the present invention, FIG. 3 is a schematic diagram of an electrophoresis measuring device according to a first embodiment of the present invention, and FIG. 4 is a diagram showing a conventional measuring device. FIG. 5 is a schematic diagram of the electrophoresis measuring device according to the second embodiment of the present invention, FIG. 6 is a circuit diagram of the same power supply device, FIG. 7 is an explanatory diagram showing temperature changes within a measurement cell when a conventional measurement device is used. 1... Constant temperature chamber, 2... U-shaped glass tube, 3,
3'... Current-carrying electrode, 4... Temperature control device, 7...
Power supply device, 10... Circulation tank, 12, 12'... Voltage measurement electrode, 15... Heater, 17... Output selection circuit, 18... Positive polarity relay switch, 19...
... Negative polarity relay switch, 20 ... Square measurement cell, 21 ... Sample specimen, 32 ... Sheathed thermocouple,
33...Temperature indicator, 45...DC voltmeter, 71
... DC power supply, 72 ... AC power supply, 73 ... Variable transformer, 74 ... Voltmeter, 80 ... Power supply device,
81... Oscillator, 82... Amplifier, 83... Pulse transformer, 84... Rectifier group, 85... Control circuit, 86-89... Diode, 90, 91...
Relay switch, 92, 97, 98... Normally closed contact, 93, 96, 100... Relay, 94, 9
5,99,102,103,104,105...
Normally open contact, 101...AC power supply, 107, 108
...Output terminal.

Claims (1)

[Scope of Claims] 1. In order to consume the same amount of power in the sample specimen before applying the measurement DC electric field to the sample specimen as the power consumed in the sample specimen when applying the measurement DC electric field to the sample specimen, A method for measuring electrokinetic phenomena characterized by supplying a current to a sample specimen. 2. The sample specimen is a suspension contained in an electrophoresis chamber, and when measuring the electrophoretic mobility of colloidal particles in this suspension, the alternating current stops the colloidal particles whose mobility is to be measured. The electrokinetic phenomenon measuring method according to claim 1, characterized in that the electrokinetic phenomenon measurement method has a frequency that can be considered as a state. 3. An apparatus for measuring an electrokinetic phenomenon in a sample, comprising a power supply for applying an electric field to a sample, the power supply having a DC power supply for applying a measurement electric field to the sample; An electrokinetic phenomenon measuring device characterized by having an AC power supply for passing an AC current through a sample specimen and an output selection circuit for selecting one of them before applying an electric field for measurement. 4. An apparatus for measuring the electrophoretic mobility of colloidal particles in the suspension in which the sample specimen is a suspension contained in an electrophoresis chamber, wherein the AC power supply stops the colloidal particles whose mobility is to be measured. The electrokinetic phenomenon measuring device according to claim 3, wherein the electrokinetic phenomenon measuring device has a frequency that can be considered as a state.