JPS5860250A - Concentration measurement in electrophoresis device - Google Patents

Abstract

PURPOSE:To increase accuracy of the measurement and obtain exact measurement data by keeping the pH value of baffer solutions in the right and left tanks of a migration tank by reversing in an constant interval the polarity of the DC current applied between the right and left tanks and at the same time making sure that the measurement starting position is located always on the side of alubumin of a specimen to be measured. CONSTITUTION:A casette 12 on which is migration diaphragm is fixed is mounted on a migration tank 22. For the DC current applied between the electrodes 29 and 29, their polarities are alternated everytime the casette 12 is changed, which keeps the concentration between both tanks 22b and 22c always uniform. In a concentration measurement unit 27, the casette 12 is moved relative to an optical detection section successively with a specified timing in the transverse axis direction and vertical axis direction, and the concentration of divided components can thereby measured always from the albumin side to the gamma side, and since the concentration curves thus obtained are drawn usually from the albumin side, the judgement of subsequent measurement data can be made exactly without error.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring concentration in a fully automated cassette type electrophoresis apparatus.

As is well known, in the electrophoretic analysis method, a sample such as a serum protein is placed on a support plate containing a certain buffer solution, and when a direct current is applied to both ends of the sample, buffer ions and charged molecules or atoms are separated from the sample. The amount of each fraction separated by the difference in separation speed is quantified by using electrophoresis in the direction of the opposite pole to the charge on the table and separation on the support in different orders of migration speed. This method measures the sample composition by In order to perform such measurements, each sample is coated on a thin film moistened with a buffer solution, the sample is run in an electrophoresis tank, it is fixed, stained, and fractionated on the electrophoresis membrane. In order to quickly and reliably test and process a large number of samples, especially recently, a method has become available in which electrophoresis membranes are made into cassettes and the entire process is automatically processed in each cassette. It has been proposed by the applicant etc.

Such automated equipment includes serum application and cassette formation processes, electrophoresis processes, staining and decolorization processes, drying processes,
Each series of steps in the concentration measurement process is performed by equipment or units of each ministry, and the sample is automatically transported between each equipment or unit by linkage in a certain order according to a predetermined program. There is.

The present invention relates to a method for measuring concentration in such an automated electrophoresis apparatus.

In such concentration measurements, generally, as shown in Figure 1, a plurality of specimens (approximately 10 to 20 specimens) are placed at regular intervals in the lateral direction (the so-called X-axis direction) on the same planar support. The sample, in which a plurality of components of each sample were electrophoresed on a straight line in the vertical direction (the so-called Y-axis direction), is held in a frame such as a cassette, and the frame is moved in the vertical direction in a plane.
By moving it in the horizontal axis direction, the fractional concentrations of multiple samples are automatically measured, and these measured values are continuously recorded together with the fractional concentration diagram.

However, according to this method, various problems mainly related to the support and electrophoresis itself arise, as described below.

(,) Support membranes such as Separax membranes, which are the supports for buffer solutions, have significant quality unevenness depending on their type.
Even electrophoresis under the same conditions does not necessarily yield the same results.

(b) This support film has significant dimensional differences due to expansion and contraction depending on various processing steps such as drying, wetting, and transparency processing, ambient temperature, humidity, etc.

(c) Electrophoresis itself is easily affected by various conditions such as the type of supporting membrane, the degree of newness and oldness due to buffer solution, temperature and use, magnitude of current and voltage, and electrophoresis time, and furthermore, the ambient temperature and It is easily affected by humidity.

For this reason, the following problems have arisen when measuring the concentration of a sample fractionated on a support membrane.

(,) In conventional concentration measurements, it was customary for an operator to actually manually measure the sample spacing, set this spacing on the machine, and then perform measurements at a constant pitch.

However, in this case, the samples are not necessarily electrophoresed at equal intervals, and even if the samples are applied at equal intervals, the spacing between the samples after electrophoresis may vary due to the expansion and contraction of the support membrane mentioned above and other reasons. Since the concentration is not constant and varies, the center line of each sample (
Scanning (in the vertical axis direction) becomes increasingly difficult, and especially in support films for multiple samples (for example, 20 samples), the deviation of this center line is added up one after another, and eventually the slit of the optical system moves away from the sample, causing the concentration to decrease. Measurement may become impossible, or measurement results may become inaccurate and measurement accuracy may deteriorate, reducing the reliability of clinical data and potentially causing misdiagnosis. For this reason, it is necessary to constantly correct the gap between the samples in the measurement process, and constant monitoring by the operator is required.

(b) There is a risk that extremely small mechanical errors in the horizontal axis direction (X direction) of the movement mechanism of the sample transport stage or optical system detection unit in the concentration measurement unit will accumulate, causing problems similar to those in (,) above. was there.

(c) Unless these problems are solved, it will not be possible to completely automate concentration measurements of large amounts of samples.

Therefore, in order to deal with such problems, in the concentration measurement unit of the fully automated cassette-type electrophoresis apparatus as described above, we have developed a method for measuring the deviation in the measurement sample interval in the horizontal axis direction and the deviation in the electrophoresis pattern in the vertical axis direction. The present applicant and others have previously proposed a concentration measurement method in which the above-mentioned optical system detection section can automatically and faithfully follow the center line of the above-mentioned electrophoretic pattern. There is.

According to this, all of the above-mentioned problems are solved, but on the other hand, new problems related to the electrophoresis method as shown below are pointed out.

Conventionally, this electrophoresis is carried out by filling both the left and right tanks 2a and 2b of the electrophoresis tank 2 with buffer solutions 3a and 3b, respectively, and placing F papers 4 and 4 on the partition wall 2C22C that partitions between them. and one end of it is connected to tank 2a.

At the same time, the electrophoretic membrane 6 supported by the cassette 5 is placed on the r papers 4, 4, and a direct current is applied between the left and right tanks 2'+ and 2b. By applying this voltage, a migration pattern of the specimen sample is formed on the migration membrane 6.

However, in this case, both the left and right cisterns 2a.

Electrode 7 provided between 2b. ．． Between 7b, the - blade side is always ■
, the other side is generally set to be energized so that the polarity is O. Therefore, as shown in FIG. 2, the buffer solution 3. ．． 3. Components 3a and 18b inside are gradually precipitated and adsorbed onto the P papers 4, 4, and the pH levels of the buffer solutions in both tanks, which should originally be uniform, become different, and as a result, the separation of the migration patterns becomes unclear. Otherwise, a problem occurs in which the length of the pattern varies.

In order to solve this problem, for example, it is possible to appropriately reverse the polarity of the current applied between both tanks 2a and 2b.
In this case, fractions (generally albumin and α
l, α2. β, r globulin (hereinafter simply α1, α2
．． The albumin side of the sample is fractionated by A called β, r, and albumin is identified as the area with the highest concentration), and each time it is reversed, the albumin side of the sample is fractionated from one side of the fractionation direction to the other side (
γ.

β, α2. α1. albumin), and in subsequent concentration measurements, the measurement start position of the optical system detection unit is reversed from the albumin side to the γ side each time, resulting in a concentration curve drawn from the albumin side. Both lines with the concentration curve drawn from the γ side are formed alternately each time the reversal occurs, causing a problem in which the measurement results are misjudged.

This invention was proposed in view of such conventional problems, and includes a method in which the polarity of the direct current applied between the left and right sides of the electrophoresis tank is alternately reversed for each electrophoresis membrane or for every predetermined number of electrophoresis membranes. At the same time, in response to this reversal, the measurement start position of the optical system detection section is reversed from one side to the other side in the vertical axis direction, thereby ensuring that the pH level of the buffer solution in both the left and right tanks is always uniform. The purpose of the present invention is to provide a concentration measuring method in an electrophoresis apparatus in which the measurement starting position can be always set on the albumin side of the measurement sample.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings from FIG. 5 onwards.

FIG. 3 schematically shows an electrophoresis apparatus to which the present invention is applied, in which reference numeral 10 indicates a serum dish storing a plurality of specimens, for example, 20 samples, and 11 a sample dish stocker for storing a plurality of serum dishes 10. , 12 is a cassette in which a migration membrane such as a cellulose acetate membrane is fixed between rigid upper and lower frames; 13 is a cassette stocker for storing a plurality of cassettes 12; 14
The above cassette 12 is used to wet the electrophoresis membrane with a buffer solution.
15 is a sample supply device that transfers the serum in the serum dish 10 to the cassette 12 that has been immersed in the buffer solution, 16 and 17 are washing devices and cleaning devices for the sample supply device 15, and 18 is a cleaning device for use. This is a stocker in Seimen.

The cassette 12 with serum applied onto the electrophoresis membrane is handled by the handler 1.
9 and is sequentially fed to each process along a handler moving conveyor line 20 that guides this handler 19.

To explain this in the order of steps, first 21 is a migration processing unit equipped with a plurality of migration tanks 22 (four tanks in the illustrated example);
24 is a staining unit that performs staining by immersing the electrophoretic membrane fixedly held in the cassette 12, 24 is a decolorizing unit that decolorizes the electrophoretic membrane by immersing it in a decolorizing solution, and 25 is a cassette in which this decolorization has been completed. This is a drying unit that dries food using a hot plate and hot air fan. The cassette 12 is released from the dryer 19 at the stage of this drying unit 25, and after drying is completed, the cassette 12 is moved to the transparent processing unit 25 by an extrusion mechanism using a chain or the like.
The electrophoretic membrane is then transferred to a transparent membrane as a pretreatment for concentration measurement. Next, the cassette 12 is sent to the concentration measurement unit 27, where optical measurement of the component concentration of each sample is performed. Then, the measured cassette 12 is discharged to the outside of the apparatus by an appropriate cassette discharge mechanism, and a series of electrophoretic analyzes is completed. The operations of each unit, the handler 19, etc., and the transfer means are all automatically controlled according to a predetermined order by a program stored in advance in the CPU built into the device, and the cassettes 12 that are sent in one after another can be continuously processed. It is something.

As shown in FIG.
A pair of partition walls 22a on which are placed.

22, left and right tanks 22b, 22c are provided, both tanks 22b, 22c are filled with a buffer solution 28.28, and electrodes 29.28 are provided in both tanks 22b, 22c.
A direct current is applied between the terminals 29 and 29.

In this embodiment, as shown in the figure, for example, in the initial state, the polarity of the tank 22b is set to ■, and the polarity of the tank 22c is set to ○, and thereafter, as shown in the figure, each time the cassette 12 is replaced Both tanks 22b.

The polarity between 22c is alternately reversed from ■ to ○ or from ■ to ■. This reversal is performed by a command from a CPU built into the device, and the CPU stores the polarity state of the current applied to each cassette.

Next, the electrophoretic film of the cassette 12 on which the electrophoretic pattern of the specimen sample has been formed is made transparent in the transparent processing unit 26 in the electrophoresis processing unit 21, and then this cassette 12 is sent to the concentration measurement unit 27 as described above. , where the concentration of the fractionated sample is measured.

In this concentration measurement unit 27, as shown in FIG.
The cassette 12 is placed on a sample transport table 30 and is moved in the horizontal axis (X-axis) direction and the vertical axis (Y-axis) direction at predetermined timing relative to the optical system detection section.

This transfer is performed, for example, by a rack and pinion mechanism in the X-axis direction and by a timing belt in the Y-axis direction, driven by a husband and wife stepping motor.

And both the left and right tanks 22b of the electrophoresis tank 22.

When the direct current applied between 22c and 22c is alternately reversed as described above, the position of albumin (generally determined as the highest concentration point) in the electrophoretic pattern fractionated on the electrophoretic membrane is determined by this reversal. is alternately inverted from one side to the other side in the vertical axis (Y-axis) direction of the electrophoretic membrane for each cassette.

Therefore, in this one state, for example, tank 22b is
The case where c has the polarity of O is the normal state N.

A case where the sentence type 22b is 01 and the tank 22C has the polarity of ■ is defined as a pole change state P. Both of these states are the internal CP of the device.
Stored in U.

As shown in FIGS. 6 and 7, position sensors 31 and 32 for positioning the sample carrier 30 in the vertical axis direction are arranged at predetermined positions on the sample carrier at a predetermined distance. In the normal state, the position sensor 31 positions the conveyance table 30, and in the pole change state, the position sensor 32 positions the conveyance table 30.

First, it is assumed that the electrophoresis is performed in the normal state N, and the resulting cassette is sent to the concentration measuring unit 27 and separated. In this case, as shown in FIG. 6, when the sample carrier 30 is transferred in the direction of the arrow 33 along the vertical axis, the position sensor 31 detects the carrier 30 at a predetermined position in the transfer direction. Control the positioning to the position shown in the figure. In this state, albumin A on the electrophoretic membrane 34 corresponds to the above polarity.
The position of Attα1.
α2. The electrophoretic patterns are fractionated in the order of β and γ).

Also, at this time, the optical system detection section 35 is located on one side of the electrophoretic membrane 34,
That is, it is set to be located on the albumin At side in the upper part of the figure.

A series of these drive controls is performed by the CPH built into the concentration measuring unit 27 based on commands from the CPU of the main body of the apparatus. From this position, the sample transport table 30 is directed toward the optical system detection section 35 by the arrow 33.
The detection unit 35 is moved in the direction indicated by the arrow 36.
As shown, the migration pattern is scanned from the albumin At side to the γ side, and the component concentration of the specimen sample is measured.

On the other hand, the above electrophoresis is performed in the pole change state P, and the cassette at this time is
Suppose that it is sent above 0. In this case, as shown in FIG. 7, when the sample carrier 30 is transferred in the direction of the arrow 33, the carrier 30 passes the position sensor 31 and is further transferred in the direction of the arrow to reach its predetermined position, i.e. A position sensor 32 detects the transport platform 30 on the rear end side in the transport direction, and upon receiving this detection signal, the CPU positions it at the relevant position as shown in the figure. In this state, in response to the polarity reversal, albumin At is reversed to the other side of the electrophoretic membrane 34, that is, to the lower side in the vertical axis direction in the figure, and from there to the upper side in the figure (Attα1,
α7. The migration pattern is fractionated in the order of β and γ).

Further, in this case, the optical system detection section 35 is located on the other side of the electrophoretic membrane 34, that is, on the lower side in the figure, contrary to the above,
At this position, it is controlled by the CPH so that it is positioned on the albumin At side. Then, for concentration measurement, the sample carrier 30 is moved in the opposite direction to that described above, that is, in the direction shown by the arrow 37, and the optical system detection section 35 is moved from the albumin A4 to the r side of the electrophoresis pattern as shown by the arrow 38. The component concentration of the specimen sample is measured.

Therefore, according to this, the albumin At of the electrophoretic pattern fractionated on the electrophoretic membrane 34 in response to the reversal of polarity.
Even though the position is reversed from 10,000 to the other side in the vertical axis direction, the measurement start position by the optical system detection section 35 follows this reversal and is always reliably positioned on the albumin side. . As a result, the resulting fractional concentration diagram also shows that albumin^ is always divided into α□, α2, . Since the images are drawn in the regular arrangement order of β and r, subsequent inspection processing can be performed accurately without errors.

Furthermore, as described above, the polarity of the DC current applied between the two tanks 22b and 122e of the migration tank 22 is alternately reversed for each cassette 12 fed into the tank 22, so that the polarity of the DC current applied between the two tanks 22b and 122e of the migration tank 22 is alternately reversed for each cassette 12 sent into the tank 22. The components of the buffer solution filled in each tank are precipitated, and the pH concentration of the buffer solution is determined in both the left and right tanks 22b.
221! This completely prevents the difference in concentration between the two tanks 22b and 122c, and keeps the concentration uniform between both tanks 22b and 122c at all times.

Similarly, in the above embodiment, it has been explained that the polarity of the DC current is reversed for each cassette 12 sent into the electrophoresis tank 22, but the present invention is not limited to this. For example, The polarity may be reversed every predetermined number of cassettes 12. In this case, the position of the albumin is reversed as described above at a corresponding interval, and it goes without saying that the measurement start position by the optical system detection section 35 is positioned on the reversed albumin side at the same interval. .

After the measurement start position of the optical system detection unit 35 is correctly positioned on the albumin At side, the component concentration is measured while automatically detecting the sample spacing in the vertical and horizontal axis directions, as described below. It will happen. That is, (,) First, the center line of the first sample A of the electrophoretic membrane 34 in which a large number of samples, for example, 20 samples, as shown in FIG. It is converted into and stored in the memory of the concentration measurement unit 27. From among these memories, the center point P (see Figures 8 and 9) of Alpumi/, which is determined as the point with the highest concentration, is found, and the starting point O of movement (this position is determined by the optical system detection unit 35 described above) is determined. (obtained from the positioning), and after determining the position, it is stored in the CPH.

This f can be easily calculated by the CPU built in the concentration measuring unit 27 using the following equation.

2 f = −X F N.

Here, F is the total length of the sample from the starting point O to the ending point Q, NI
, N are the numbers of samples from the starting point 0 to points Q and 2, respectively.

Next, when aligning to the next sample B, the sample transport table 35 is again moved in the vertical axis direction to the position of the center point P of the albumin and stopped there.

(b) Next, while moving the sample transport table 35 in the horizontal axis (X-axis) direction, the voltage change in (a) is detected by the four-way optical system detection unit 35, and based on the amount of change in voltage, the next sample B The determination is continued based on the albumin having the highest concentration, and this is stored in the CPU.

In this case, the locus of point P in the horizontal axis direction is y/-y/.

(c) Further, continue moving the sample transport table in the horizontal axis direction until it reaches the midpoint R with sample B (the first point in the transparent area between samples A and B).
As shown in Figure 0, the voltage value is stopped at the peak (ie, the point where the concentration is the thinnest).

(d) In order to determine the albumin center point S of the next sample B, the CPU is caused to perform the following editing operation.

The albumin fractionation ranges S and -S2 are specified from the stored values described in sections (b) and (c) above (see FIG. 10).

The voltage level in this range 81 to S2 is actually the first voltage level.
As shown in Figure 1, it fluctuates considerably and is not uniform.

Therefore, the center point S cannot be determined based only on changes in density. To do this, certain conditions must be met to detect the voltage fluctuations (maximum and minimum points), such as the difference between the maximum and minimum values (
(amount of change), and cancel extreme level fluctuations.
When celling, data changes are reduced, and data that is smaller than the amount of change in the set variation range by /11/J is treated as the same data. By performing the above editing operations, the values of S□~$2 become the same data, and B
The center point S of the sample can be determined as the midpoint of the range S□ to S2.

(,) Next, the sample carrier is returned to the center point S of the albumin of sample B, and further the sample carrier is moved in the vertical axis direction, and this carrier is returned to the movement start point o4. It becomes possible to measure the concentration of all fraction components from At to γ.

Thereafter, by repeating the above method, the concentration of the next sample C and subsequent samples is measured.

As described above, automatic detection of the sample interval in the horizontal axis direction is performed.

Similarly, in order to detect the interval between samples where a shift occurs in the vertical axis direction, the same operation as for detecting the sample interval when a shift occurs in the horizontal axis direction described above may be performed.

The slits in the optical system detection section 35 are, as shown in FIGS. 15(a) and 15(b), a slit plate 40 provided with slits 41 and 42 located at right angles to each other. A support frame 43 is used that is slidably inserted into the support frame 43 in the directions of arrows 44 and 45. This slit 4
The slit 1 is arranged in the vertical axis direction, that is, perpendicular to the fractionation direction of the sample, and is used exclusively as a slit for concentration measurement. Further, the slit 42 is perpendicular to the horizontal axis direction, that is, the arrangement direction of each sample, and is used as a slit for detecting sample intervals in the vertical and horizontal axis directions.

To switch between both slits 41 and 42, use the slit plate 4
0 may be slid by a fixed length KPJT in the direction of the arrow 44 or 45.

FIGS. 16(a) and 16(b) show this switching state, and the figure (&) shows the case where the slit 41 is in use, and this slit 41 is placed above the light transmission hole 46. and the slit plate is switched and set to the concentration measurement state.

In addition, in FIG. 4B, the slit plate 4o is switched to the sample interval detection state so that the slit 42 is located above the transmission hole 46.

All switching between the slits 41 and 42 can be performed automatically.

Note that the slit is not limited to this, and may have various other configurations.

For example, as shown in FIG. 14, a slit plate 41'' in which a slit 41' for density measurement is provided parallel to the horizontal axis direction.
and a slit plate 47' in which a slit 42' for measuring sample spacing is provided parallel to the vertical axis direction are constructed separately, and both slit plates are set in a positional relationship at right angles to each other, The slits 41' and 42' may be switched between the slits 41' and 42' by mutually rotating both slit plates by a predetermined angle.

Furthermore, instead of the above-mentioned switching slit, it is also possible to provide an optical device for detecting the sample interval independently and separately from the optical device for measuring the concentration.

In the above embodiment, the optical system detection section was fixed and the sample transport table was moved in the vertical and horizontal directions for the concentration measurement, but on the contrary,
Alternatively, the sample carrier may be fixed and the optical system detection section may be moved in the vertical and horizontal directions relative to the sample carrier. In this case as well, the concentration can be measured in exactly the same manner as described above.

According to the method for detecting sample spacing in sections (,) to (e) above, the scanning center line of each migration pattern is automatically detected, and the optical system detection section can faithfully scan on this center line. This has the advantage that measurement accuracy is further improved and accurate measurement data can be obtained.

As explained in detail above, in the concentration measuring method according to the present invention, the polarity of the direct current applied between the left and right of the electrophoresis tank is alternately reversed at regular intervals. The pH concentration of each filled buffer solution is maintained uniformly at all times, thereby ensuring the separation of the specimen sample and obtaining a clear electrophoresis pattern.The length of this pattern is also made uniform, and as a result, the measurement This has the advantage that accuracy is further improved and accurate measurement data can be obtained.

Further, in the present invention, in response to the reversal of the polarity, the measurement start position of the optical system detection section is always reliably positioned to follow the albumin side of the fractionated specimen sample, so that the polarity is reversible. Despite the reversal, there is no inconvenience that the measurement starts from the albumin side in some cases, or from the Fi, r side in other cases, and γ is always started from the albumin side.
Since the concentration of the fractionated components can be measured from the side, and the resulting concentration curve is always drawn from the albumin side, subsequent determinations of measurement data can be made accurately without errors.

Moreover, in this invention, the reversal of the polarity and the positioning of the measurement start position of the optical system detection section corresponding to this reversal on the albumin side can all be performed automatically under the control of the CPH built into the device. Therefore, the effect of fully automating the device is extremely large.

[Brief explanation of the drawing]

Figure 1 shows an example of the electrophoresis pattern for multiple samples;
Figure 3 is a cross-sectional view showing the configuration of a conventional electrophoresis tank, Figure 3 is an explanatory diagram of the overall configuration of an electrophoresis apparatus to which the present invention is applied, and Figure 4 shows the configuration of the electrophoresis vessel in the electrophoresis apparatus and the voltage applied thereto. 5 is a diagram illustrating a schematic configuration of a concentration measuring unit to which the present invention is applied and its operating state. FIGS. 6 and 7 are diagrams illustrating an optical system according to the method of the present invention. The positioning diagram when locating the measurement start position of the detection unit on the albumin side is a diagram explaining the order, Figure 8 is a fractional concentration diagram, and Figure 9 is a detection of the electrophoresis pattern and sample interval when the sample interval is different. Diagrams explaining the operation, Figures 10 to 12
The figure is a voltage level diagram for the case shown in Figure 9, and Figure 16 (a).
, (b) are diagrams illustrating the slit used in the method of the present invention, (,) before switching and (b) after switching. FIG. 14 is a diagram showing another example of the same slit. X...horizontal axis, Y...vertical axis, 12...cassette, 2
1...Migration processing unit, 22...Migration tank, 22,
．． 22a--Partition wall, 22b, 22C--Both left and right tanks, 2T--Concentration measurement unit, 28--Buffer solution, 29.29--Electrode, 30--Sample carrier, 3
1.32...Position sensor, 34...Migration membrane, 35
...Optical system detection section, At...albumin, N...
Normal position T, P...Ball position. Figure 1 1 → × Figure 2 Figure 8 Figure 9 Figure I-X Figure 10 Electricity Figure 12 Medium pressure Figure 14 Figure 41"

Claims (1)

[Claims] (1) A sample in which multiple specimens are arranged at regular intervals in the horizontal direction on the same flat support, and multiple components of each specimen are migrated in a straight line in the vertical direction, is transferred to the optical system detection section. An electrophoresis device that measures the fractional concentration of a sample electrophoresed by moving the electrophoresis device in the vertical axis and the horizontal axis perpendicular thereto, or by moving the optical detection unit in the vertical and horizontal directions with respect to the sample. In the concentration measuring unit in , the polarity of the direct current applied between the right and left sides of the electrophoresis tank provided in the electrophoresis device is adjusted depending on the support that is sequentially fed into the electrophoresis tank, or every predetermined number of supports. and in response to this reversal, the measurement start position by the optical system detection section of the concentration measuring unit is alternately reversed from one side of the vertical axis of the support to the albumin side reversed to the other side. A method for measuring concentration in an electrophoresis apparatus, characterized in that: