JPS60202328A - Electrophoresis-speed measuring device for suspended particle - Google Patents

Abstract

PURPOSE:To obtain a highly reliable result with few errors, by selecting the adequate result among the results obtained by executing a plurality of analyzing methods. CONSTITUTION:A program of frequency analysis by a Fourier transformation method is imparted to an operating device 8. A program of a zero crossing method is set in an operating device 9. The devices 8 and 9 read the data of the same output from a RAM7 and perform the different operations, respectively. To which method the measuring condition is suitable is not clear, therefore, the product of the results of the two operations is made to be the final data. In this figure, the operation of the product is carried out by the device 9, and the result is displayed on a display device 10.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an apparatus for measuring the electrophoretic velocity of suspended particles.

(Prior Art) When biological cells are suspended in a suitable solvent and subjected to electrophoresis by applying an electric field, it is possible to determine the charge on the cell surface based on the migration speed of the cells, and the cells can be classified. One method for measuring the electrophoretic velocity of such suspended particles is as follows. Particles are suspended in an electrophoresis tube, and when the tube is illuminated and viewed from the side, the particles appear as glowing dots. This is projected onto the grating using a lens, and a light receiving element is placed after the grating to receive the light transmitted through the grating. When suspended particles undergo electrophoresis, the image of the particles moves on a grid. Since the particle image is a bright spot, when the particle image moves on the grid, the amount of light incident on the light receiving element decreases when the particle image passes through the grid lines. Considering the case where there is only one particle, the output of the light receiving element fluctuates at a period determined by the speed of the particle and the pitch of the grating, so the speed of the particle is calculated from this period. When there are many particles and they have a velocity distribution, the output of the light receiving element is a combination of many signals with various periods.

Generally, such a signal is obtained, and the distribution of electrophoretic velocity of particles is determined by frequency analysis of this signal. In this case, as the frequency analysis method, a Fourier transform method, a zero-cross counting method, a furnace correlation method, etc. are used. For example, the Fourier transform method gives correct results when the particle density is high, but as the particles settle and the number of particles decreases, the reproducibility of the results deteriorates. The zero-crossing method is the opposite, giving better results when the number of particles is small.

In this way, various frequency analysis methods have their own advantages and disadvantages.
It gives good results under suitable conditions. However, since conventional electrophoresis measurement devices apply only one type of frequency analysis method, measurement errors are likely to occur if measurement conditions are not appropriate.

The purpose of the present invention is to improve the reliability and accuracy of measurement results of electrophoretic velocity of suspended particles.

2. Configuration The electrophoresis measurement device of the present invention applies multiple types of frequency analysis methods to the same signal obtained by the measurement device to obtain multiple results, and selects a valid measurement result from among them. It is something.

E. Embodiment FIG. 1 shows an embodiment of the present invention. 1 is an electrophoresis tube,
Floating particles are designed to conduct electrophoresis in a direction perpendicular to the plane of the figure. Reference numeral 2 is a light beam that illuminates the floating particles in the electrophoresis tube. Reference numeral 3 is an objective lens that views the illuminated floating particles from the side, and forms an image of the floating particles on the grid 4. In this image, particles appear as bright spots against a dark background. The light transmitted through the grid passes through a condensing lens 5 and is made incident on a silicon photocell 6. The output signal of the silicon photocell 6 passes through a preamplifier, is A/D converted, and is sent to the RAM 7.
be memorized. RAM'i' has a structure of 2048 words (16 bits per word). RAM'7 is commonly accessed by both arithmetic processing units 8 and 9.

The arithmetic processing unit 8 is provided with a program for frequency analysis using the Fourier transform method, and the arithmetic processing unit 9 is provided with a program for the zero-cross method.

The two arithmetic processing units 8 and 9 read out the same measurement output data from a common RAM'/ and perform different arithmetic processing on them.

What is determined by calculation processing is the spectrum of the electrophoretic velocity of suspended particles, and if either frequency analysis method yields completely correct results, the spectral data obtained by both calculation processing devices should match. , each frequency analysis method has measurement conditions for which it is suitable, and actual measurement conditions are generally not necessarily optimal for any method, so the spectra determined by each method do not contain errors. However, it is normal that they do not match each other. As mentioned above, the Fourier transform method gives a velocity spectrum with less error when the number of particles is large, and the zero-crossing method gives good results when the number of particles is small. Since it is actually unclear which method is suitable for the measurement conditions, the result with the least error is extracted from the two calculation results themselves. One method is to plot the results obtained by the arithmetic processing unit 8.9 in a graph and visually select the one with the smaller velocity distribution. Since the visual inspection method involves subjectivity and is troublesome, a method of automatically comparing the two results may be considered. In the case of the illustrated embodiment,
The product of the two calculation results is used as the final velocity distribution data. That is, the calculation results of the calculation processing device 8 are expressed as f, (x),
When the calculation result of step 9 is g (x), the product F (x)
= f (x) g (X) is the final velocity distribution data. Here, X is the frequency of the component wave constituting the output signal of the light receiving element 6, which corresponds to the migration speed of the particles, and the function value f1g is the amplitude of the component of frequency X, that is, the speed corresponding to frequency X. The amount is proportional to the number of particles held. Figure 2 shows an example of the results of two operations performed by the arithmetic processing unit 8.9, where a is the result of the Fourier transform method of 8;
b is the result of the zero cross method of 9, and C is the product of both. This method of calculating the product is a type of majority voting method, and X, which shows the maximum value in the product, is the frequency component that is determined to be the largest in either of the two analysis methods. In the apparatus shown in FIG. 1, the arithmetic processing circuit 9 for this product takes charge of the calculation, and the result is displayed on the display device 1O.

In the above embodiment, two arithmetic processing units are used to execute two analysis methods at the same time, but this is in order to obtain the result as quickly as possible. It goes without saying that a different frequency analysis method may also be implemented.

Further, the frequency analysis method is not limited to two types. For example, when three types of analysis methods are executed and the spectral function obtained by each method is f(X) l g (x) l h(X),
Three products f@g, l! :f@h,! :g@h may be calculated, and the one showing the largest peak among them may be used as the final result.

In electrophoretic velocity measurement, which involves forming an image of suspended particles on a grid, there are various analysis methods for determining the velocity distribution from the output signal of the light-receiving element, but each of these methods has its own advantages and disadvantages. However, the measurement conditions that are considered appropriate vary and generally include errors of a certain degree. Therefore, when calculating the velocity distribution using only one type of analytical method as in the past, the reliability of the results is insufficient. According to the present invention, since a plurality of analysis methods are executed and appropriate results are selected from the results obtained by each method by a comparative reduction amount, highly reliable results with few errors can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an apparatus according to an embodiment of the present invention, and FIG. 2 is a graph showing an example of frequency analysis results. DESCRIPTION OF SYMBOLS 1... Electrophoresis tube, 2... Illumination light flux, 3... Objective lens, 4... Grid, 5... Condensing lens, 6...
Silicon photocell 7...RAM, 8.9... Arithmetic processing unit, 10... Display device. Agent Patent Attorney Kosuke Agata

Claims (1)

[Claims] In a configuration in which an image of suspended particles is formed on a grid, the light transmitted through the grid is received, and the received light output is frequency-analyzed to determine the velocity distribution of the suspended particles, the data processing device can process multiple types of frequency analysis methods. Electrophoretic velocity measurement of suspended particles characterized by having a program for executing multiple types of frequency analysis methods and selecting the optimal result from the results obtained by each analysis method. Device.