JPH03220445A - Analyzing method of inspection of component by test paper - Google Patents

Abstract

PURPOSE:To improve the measuring accuracy by a method wherein a white light is cast to a color rendering part of a test paper, and the reflecting light is decomposed into four factors, namely, red, green, blue lights and brightness and taken out as digital signals, so that the concentration is measured based on the digital signals. CONSTITUTION:A white light is cast via an infrared cutting filter to the color rendering part of a test paper after having been soaked in a sample liquid. The reflecting light is decomposed into four factors, namely, red, green and blue lights and brightness, and read out by a photodetector as an electric signal and then a digital signal. For instance, the normal logarithm for the electric signal by the quantity of the reflecting light is set to 0-2.5, and this value is changed to a digital value. A value of the four factors of a subject component at every known concentration is obtained with use of a standard sample beforehand, and the sum or ratio of optional one to four values of the four factors and a combination of the sum or ratio of the values are arranged to correspond to known concentrations. Therefore, when the corresponding value of the four factors of a component of a sample to be analyzed is obtained, the concentration of the component can be immediately detected.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention is directed to, for example, components (IN,
This invention relates to an analytical method for component testing using test strips for determining the concentration of components in liquid samples, such as components in liquid samples (proteins, occult blood, etc.), oils, drinking water, foods, and other liquid materials.

<Conventional technology and its problems> Normally, when measuring various components in body fluids, the sample and an appropriate detection reagent are reacted in a liquid phase to develop a color, and then photometry is performed at a characteristic absorption wavelength and the result is Lambertian.・A common method is to analyze based on Bear's law and quantify the amount of ingredients.

However, in recent years, with the development of dry chemistry, many tests have been made using so-called "test paper", which is made by impregnating a hygroscopic material such as a filter paper with a detection reagent, drying it, and pasting it on a stain-like substrate.
Simultaneous testing methods are becoming widespread, and this method is the mainstream, especially for urine.

Now, when measuring with test strips, the judgment is done by the eyes of the general public, but there is a limit to the number of things that can be processed per unit time, there are significant individual differences, and there are hygiene issues. Automatic analyzers are widely available on the market that use an integrating sphere reflectance photometry method to read test strips by irradiating the colored area with multiple light beams with characteristic wavelengths and measuring the reflected light.

However, these conventional automatic analyzers have low reading accuracy (analytical ability), and sometimes their judgment is inferior to the human eye, and in the case of urine, the color tone of the urine itself varies from person to person, which can interfere with reading. This has the disadvantage that blank pads must be attached to prevent this from occurring.

<Means and effects for solving the problem> In view of the above-mentioned problems with the conventional technology, as a result of intensive research, the present inventor has discovered a method for detecting subtle changes in color tone of the colored portion of the test strip that is to be read by an automatic analyzer. The reflected light from the colored area is separated into four elements of red light, green light, blue light, and brightness by each color filter, and these are converted into electric signals by the light receiving element, and then converted into digital signals. By analyzing using
It was discovered that the accuracy exceeds the accuracy of conventional automatic analyzers, and that the color tone of the urine itself does not interfere with the use of a blank band.

In other words, the analytical method for component testing using the test strip of the present invention is as follows:
The colored part of the test paper used to measure the components in the sample is irradiated with white light, and the reflected light is separated into four elements consisting of red light, green light, blue light, and brightness, and extracted as digital signal values. The first feature is that the concentration of the target component is determined based on this digital signal value.

To read the four-element digital signal values using an automatic analyzer, first, white light is irradiated onto the colored part of the test paper after it has been immersed in the sample solution through an infrared cut filter, lens system, and glass fiber, and the reflected light is measured. The light is guided through a glass fiber, separated into four elements: red light, green light, blue light, and brightness, and read as an electric signal and then a digital signal by the light receiving element as described above. When converting the electric signal into a digital signal value, for example, the common logarithm of the electric signal value depending on the amount of reflected light is set to a value of 0 to 2.5, and this value is used as the digital value.

In addition, in the analysis method having the first feature above, as a more specific analysis method, all of the above four elements or any two
An analysis method can be adopted in which the concentration of the target component is determined based on the total value of the digital signal values of an element or three elements.

Similarly, in the analysis method having the above-mentioned first feature, as a more specific analysis method, the concentration of the target component is determined based on the ratio of digital signal values of all four elements, or any two or three elements. can be adopted.

Similarly, in the analysis method having the above first characteristic, as a more specific analysis method, the total value of digital signal values of all four elements, or any two or three elements, and the total value of digital signal values of all four elements, or any two or three elements. It is possible to adopt an analysis method in which the concentration of the target component is determined by using the ratio of digital signal values of two or three elements together.

Similarly, in the analysis method having the first characteristic described above, as a more specific analysis method, an analysis method can be adopted in which the concentration of the target component is determined based on the digital signal value of a specific one of the four elements.

The analysis method of the present invention first uses a standard sample to obtain the values of four elements at each known concentration of the target component, and then
Using the sum, ratio, or combination of any one to four values of the elements, the value of the sum, ratio, or combination is associated with each of the known concentrations. That is, each concentration of the target component is associated with the value of the sum, ratio, combination, etc. of the aforementioned elements.

Once the concentration of the target component and the corresponding value based on the four elements have been determined, the concentration of the target component in the sample can be determined by obtaining the corresponding value based on the four factors for the target component of the sample that you actually want to analyze. can be determined instantly.

In order to more clearly explain the analysis method of the present invention for concentration determination, a specific example will be described below.

Now, for example, urine test strips prepared under certain conditions are 1.0■/dl, 0.6■/dl! , 0.3■/d1
．． 0.2■/d! , 0.1■/d1, 0.05■/d
l, 0.02■/dl, 0.00■/d! Soak 10 test strips for each concentration in the "occult blood" standard solution of , and calculate the digital signal values of the four elements brightness (V), blue (B), green (G), and red (R), Take the ratio of the digital signal values of each element and the total of the digital signal values of the four elements, and calculate this as shown in Figure 1 (a), (b), (c), (d), (e), (f), Make a list as shown in (g) and (h), and select indicators that can determine (identify) each occult blood concentration. In FIG. 1, the symbol SD is the standard deviation value, and the symbol CV is the coefficient of variation.

From FIG. 1, as an index for determining occult blood concentration, the sum of the four elements is used as the first determination index (1), and the B/G ratio in the high concentration region is used as the auxiliary determination index (II), that is, the first determination By setting index 1=V+B+G+R and auxiliary determination index 11=B/G, the occult blood concentration can be determined as shown in FIG.

In Figure 2, the symbol N is a symbol that allows the occult blood concentration to be considered to be 0.6/dl, regardless of the value of the auxiliary judgment index, if the first judgment index, ■, is 5.30 or higher. .

As is clear from FIG. 2, the first judgment index 1=V+B+
By adopting G+R1 auxiliary judgment index 11=B/G,
The concentration of occult blood can be determined in nine stages. This represents a significant improvement in the measurement accuracy of testing methods using test strips, whereas conventional automatic analyzers were only able to determine occult blood concentrations in five levels at most.

Next, as another specific example to explain the present invention in detail, 4
A case is shown in which the concentration of a target component in a sample is determined using the remaining three elements V, G, and R, excluding blue (B) among the elements (■, B, G, and R).

In the case of urine test strips, it is well known that there are individual differences in the color tone of the urine sample itself, which causes errors in identification accuracy during reading. To prevent this, automatic analyzers are widely available on the market that use a blank pad attached to the urine test strip to correct this error and read the coloration of the urine test strip.

However, according to the analysis method of the present invention, it is possible to provide an analyzer with high identification accuracy without performing such operations. Normally, differences in the color tone of urine itself are mainly due to yellowish tone, and severe chyle urine and red hematuria due to massive bleeding in the digestive system are treated with urine test strips for the purpose of primary screening tests. Not applicable.

Figure 3 shows urine test strips prepared under certain conditions.
Purified water and 4.0■/d! These are the results of measuring the four elements of brightness (V), blue (B), green (C,), and red (R) by immersing it in a bilirubin solution (dark yellow).

As is clear from a glance at Figure 3, occult blood (senkera)
It can be seen that the "blue (B)" color is fluctuating except for the dirt. Therefore, when determining urinary occult blood and extradiabetic concentration using this test strip, exclude element B and leave the remaining 3.
Elements (2), G, and R make it possible to perform concentration determination without being affected by the yellowish tone shading of urine with the first determination index 1=V+G+R.

As an example, the case where the concentration of protein in urine is determined by the analysis method of the present invention will be described below.

Figure 4 shows urine test strips prepared under certain conditions at 1000■/d1, 700■/d1, and 500■/d.
1.300■/d! , 200■/d1, 100■
/d1.30■/d1, 0■/d1, Soak 10 test strips for each concentration in each urine protein standard solution, and measure the brightness (V), blue (B), green (G), This is a list of each element value of red (R), the ratio of each element, and the [total of four elements excluding blue (B)].

Based on the list in FIG. 4, the first determination index 1=V+G+R can be adopted as an index for determining the concentration of urine protein. Then, as an auxiliary index for more detailed concentration determination, the following auxiliary determination index 11=G/R can be employed.

Using these two indicators, the concentration of urine protein can be determined as shown in FIG.

The urine test strip used in this example was originally 1 for "urine protein."
000■/dl, 300■/d1.100■/d! ,3
Six concentrations are identified: 0 ■/d1, trace amount, and 0.0 ■/dl, but as is clear from Figure 5, concentration determination using the analysis method of the present invention allows concentration discrimination in 10 levels. It is. On the other hand, conventional automatic analyzers are limited to five levels of discrimination.

In the above specific explanation, in the analysis method of the present invention using the four elements V, B, and GSR, when the concentration is determined based on the sum of the four elements, or when the determination is performed by supplementing the ratio between the elements. , and cases where determination is made using the sum of three of the four elements or by supplementing the ratio between the elements to the sum of the three elements have been described, but the present invention is limited only to the specific methods explained in these specific examples. It is not something that will be done. The present invention uses (1
) Judging the concentration of the target component based on digital signal values of all or any two or three elements of brightness (V), blue (B), green (G), and red (R) of the four elements decomposed into zero, Analysis method for component testing using test strips.

(2) All of the 4 elements decomposed into 0, or any 2 or 3
An analysis method for component testing using test strips that determines the concentration of target components based on the ratio of the digital signal values of the elements.

(3) All of the 4 elements decomposed into 0, or any 2 or 3
An analysis method for component testing using test strips, in which the concentration of a target component is determined using a combination of the digital signal value of the component and the ratio of the digital signal value of all four components or any two or three components.

(4) An analytical method for component testing using test strips, in which the concentration of the target component is determined based on the digital signal value of a specific one of the four components divided into three.

Naturally, the method described above will be adopted.

The present invention naturally includes within its scope the analysis methods (11 to (4)) above.

In addition, when determining the actual concentration of the target component using the analysis method of the present invention, indicators and corresponding conditions for determination can be entered in advance into the computer of the control unit of the automatic analyzer.
The process up to the determination of the concentration of the target component can be performed automatically.

<Example 1> (Determination of concentration of occult blood in urine) First determination index 1
=V+B+G+R Auxiliary judgment index I [=B/G This index and the corresponding conditions (judgment criteria) shown in FIG. 2 were entered in advance into the computer of the control unit of the apparatus to determine the concentration of occult blood in the urine.

Occult blood in actual urine: 1.0■/dI, 0.6■/dl, 0.3■/d
1.0.2■/d1, 0.1■/dl, 0.05■7d
l, 0.02g/d! , 0.00■/dj.

Add 10 urine test strips for each concentration to each sample solution (
(prepared under certain conditions) was immersed, and then the concentration was determined using an automatic analyzer in which the first determination index, the auxiliary determination index, and the corresponding conditions were input into the control unit in advance as determination criteria. The values of the four elements and the judgment results for each sample solution are
Shown in figures (a) to (h).

As is clear from Fig. 6, although there is slight variation in the medium and high concentration range of 0.2 to 0.6 ■/d1, according to the method of the present invention, the urinary occult blood concentration of the eight types prepared can be accurately determined. I judged it. On the other hand, with conventional automatic analyzers, as shown in Figure 7, negative (NEG), trace (TR), small (
The concentration could only be judged in five stages: SM), medium (MOD), and large (LG).

That is, by using the method of the present invention, it is possible to automatically determine the urinary occult blood concentration with higher accuracy using the same human urine test strip.

<Example 2> (Determination of protein concentration in urine) First determination index I = V + G + R auxiliary determination index ff = G/R and the corresponding conditions (determination criteria) shown in FIG. was input to determine the concentration of protein in the urine.

The procedure is to add protein to actual urine at 1000■/d1 and 700■/d! , 500■/
d1.300+og/dl, 200w/a, 1
00■/df, 30I1g/d1, 0■/d! After soaking 10 urine test strips (prepared under certain conditions) for each concentration in a sample solution containing each of . The results are shown in Figures 8 (a) to (h).

As is clear from FIG. 8, the analytical method of the present invention determined eight levels of concentration, although there were some errors.

In contrast, with conventional automatic analyzers, as shown in Figure 9,
300■/d1 or more cannot be judged well.

<Example 3> (Determination of the concentration of ketone bodies in urine) Using the first determination index 1 = V + B + G + R and the corresponding conditions (determination criteria) shown in Fig. 11 (without using the auxiliary determination index), this index and the correspondence Conditions were entered in advance into the computer of the control unit of the automatic analyzer to determine the concentration of ketone bodies in urine.

The procedure is to add ketone bodies to actual urine at 100■/d1, 70■/d1, 40■/d1.20■
/d! , 10■/d1, 0■/d1. After soaking 10 urine test strips (prepared under certain conditions) for each concentration in the sample solutions, the above indicators and corresponding conditions were determined. The concentration was determined using an automatic analyzer. The results are shown in Figures 10 (a) to (f).

As is clear from FIGS. 10(A) to 10(F), according to the analysis method of the present invention, six levels of concentration determination can be performed almost completely.

<Example 4> (Determination of sugar concentration in urine) First judgment index 1 = V+B+G+R Auxiliary judgment index 11=G/R Compatibility conditions (judgment criteria): As shown in FIG.

be entered in advance into the computer of the control section of the automatic analyzer,
The concentration of sugar in the urine was determined.

The procedure is to add sugar to actual urine at 1000■/d1, 500■/d1, 300■/d
! , 200■/(17, 100■/d1, 50■/
Sample solutions containing dl and 0.dl/dl were prepared and automatically determined using the same method as in each of the above examples. The results are shown in Figures 13 (a) to (g).

As is clear from FIG. 13, the analytical method of the present invention was able to almost reliably discriminate the seven levels of concentration, although there was some variation.

<Example 5> (Determination of protein concentration in urine) Automatic analysis of protein in urine using a urine test strip prepared under certain conditions, different from the urine test strip used in Example 2. The concentration was determined using a machine.

The indicators and conditions that are input in advance into the computer of the control section of the automatic analyzer are as follows: First judgment indicator 1 = V + G + R Corresponding conditions (judgment criteria): As shown in Fig. 14.

The procedure is to add protein to actual urine at 1000■/dl, 500■/d1, and 300■
/d1.100mg/d1, 30qr/d1, 0
asr/dl.

Sample solutions were prepared and automatically determined using the same method as in each of the above examples. The results are shown in Figures 15 (a) to (g).

As is clear from FIG. 15, although there was some variation, it was possible to judge the concentration in seven levels.

Note that in this embodiment, blue (B), which is influenced by the color tone of urine itself, is excluded from the first determination index.

Furthermore, unlike the second embodiment, the present embodiment does not use the auxiliary determination index II=G/R. This is because the conditions for preparing the urine test strips used were different between Example 2 and Example 5.

In other words, since the preparation conditions for the same human urine test strips are different between, for example, those made by company A and those made by company B, it is necessary to obtain judgment indicators and corresponding conditions (judgment criteria) in advance in accordance with these. Conversely, if you obtain judgment indicators and corresponding conditions (judgment criteria) in advance for test papers created under various conditions (in reality, test papers from each paper), After that, the concentration of the target component can be determined automatically by simply scratching any test paper from any company, which demonstrates the great advantage and usability of the analysis method of the present invention.

<Example 6> (Determination of concentration of nitrite in urine) First determination index 1 = G Corresponding conditions (determination criteria): As shown in FIG. 16.

be entered in advance into the computer of the control section of the automatic analyzer,
The concentration of nitrite in urine was automatically determined.

The procedure is to remove nitrite in the urine. 110PP, 7PPM, 5PPM.

3PPM, IPPM, OPPM.

Each sample solution was prepared and automatically determined using a urine test strip (prepared under certain conditions) in the same manner as in the above-mentioned Examples.

The results are shown in FIGS. 17(a) to (f).

It is clear from FIG. 17 that the concentration of urinary nitrite can be determined in six levels. Conventional automatic analyzers could only make two-step judgments: negative and positive.

<Example 7> (Determination of concentration of nitrite in urine) Using a urine test strip (manufactured by Company D) prepared under certain conditions different from the urine test strip (manufactured by Company A) used in Example 6. The concentration of nitrite in urine was determined.

First judgment index 1 = G or First judgment index 1=G/R, Compatibility conditions (judgment criteria): As shown in FIG.

Automatic determination was made using the automatic analyzer of the present invention in which the above-mentioned first determination index and corresponding conditions were input into the computer section.

The procedure is to add nitrite to the urine at 110PP, 7PPM, 5PPM, 3PP
M, IPPM, OPPM.

A sample solution containing each of these was prepared and automatically analyzed in the same manner as in the above-mentioned Examples using urine test strips manufactured by the above-mentioned company.

The results are shown in FIGS. 19(a) to 19(f).

As is clear from FIG. 19, urinary nitrite could be determined with certainty on a 7-level scale.

<Example 8> (Determination of sugar concentration in urine) Using a urine test strip (manufactured by W company) that was prepared under different conditions from the urine test strip (manufactured by A company) used in Example 4, The sugar concentration in the urine was determined.

First judgment index I = V + B 10 G 0 R Auxiliary judgment index I [=B/R Compatibility conditions (judgment criteria): As shown in FIG.

was programmed in advance and input into the computer of the control section of the automatic analyzer for automatic determination.

The procedure is to add sugar to the urine at 1000■/d1, 500■/dl, and 300■/dl.
dl.

200■/d! , 100■/d1, 50■/d1
．． Sample solutions containing 0.0 μm/dl were prepared and automatically analyzed in the same manner as in the previous example.

The results are shown in FIGS. 21(a) to 21(g).

As is clear from Figure 21, 1 in urine is definitely present! The concentration could be judged in 7 levels.

Note that in this example, the determination index and corresponding conditions are different from those in Example 4, but this is due to the difference in the conditions for preparing urine test strips. In other words, in the present invention, even for test strips made by various companies under different conditions, by obtaining the judgment index and corresponding conditions (judgment criteria) in advance, it is possible to determine the appropriate test paper no matter what kind of test paper is used. Automatic judgment is possible.

Effect> As is clear from the above description and examples, the present invention has the following effects:
The reflected light from the colored part of the test strip is separated into four elements: red light, green light, blue light, and brightness, and extracted as a digital signal value, and the concentration of the target component is determined based on this value. As a result, it has become possible to perform automatic component analysis using test strips more accurately, precisely, and quickly.

[Brief explanation of drawings]

Figures 1 (a) to (h) are 4 % for the occult blood standard solution.
A diagram showing the digital values of the elements. Figure 2 is a diagram showing the judgment index and corresponding conditions for determining the concentration obtained for occult blood. Figure 3 is a diagram showing the determination index and corresponding conditions for determining the concentration of occult blood. di
A diagram showing the results of measuring the four elements of each component in bilirubin solution. Figures 4 (a) to (h) are diagrams each showing the digital values of the four elements for protein standard solutions. Figure 5 shows the results for urine protein. Figures 6 (a) to (h) showing the judgment index and corresponding conditions for concentration judgment obtained for the
7 is a diagram showing the determination range of urinary occult blood concentration using a conventional automatic analyzer, and FIGS. Figure 9 shows the determination range of urinary protein concentration by a conventional automatic analyzer; Figures 10 (a) to (e) show the determination results in Example 2; Figure 11 shows the results. Figure 12 is a diagram showing the determination index and corresponding conditions in Example 3, Figure 12 is a diagram showing the determination index and correspondence conditions in Example 4, and Figures 13 (A) to (G) are the determination results in Example 4, respectively. FIG. 14 is a diagram showing the determination index and corresponding conditions in Example 5. FIGS. 15 (A) to (G) are diagrams each showing the determination results in Example 5. FIG. Figure 17 shows the determination results in Example 6, Figure 18 shows the determination index and response conditions in Example 7, Figure 19 shows the determination index and corresponding conditions in Example 7. Figures (A) to (F) are diagrams showing the determination results in Example 7, respectively. Figure 20 is a diagram showing the determination index and corresponding conditions in Example 8. Figures 21 (A) to (G) are diagrams showing the results of the determination in Example 7. 12 is a diagram showing the determination results in Example 8. FIG.

Claims (5)

[Claims] (1) In the colored part of the test paper that measures the components in the sample,
It irradiates white light, separates the reflected light into four elements consisting of red light, green light, blue light, and brightness, extracts it as a digital signal value, and determines the concentration of the target component based on this digital signal value. An analytical method for component testing using test strips. (2) The analysis method for component testing using a test strip according to claim 1, wherein the concentration of the target component is determined based on the total value of digital signal values of all four elements, or any two or three elements. (3) The analysis method for component testing using a test strip according to claim 1, wherein the concentration of the target component is determined based on the ratio of digital signal values of all four elements or any two or three elements. (4), using the total value of digital signal values of all four elements or any two or three elements together with the ratio of digital signal values of all four elements or any two or three elements; The analysis method for component testing using a test strip according to claim 1, wherein the concentration of a target component is determined. (5) The analysis method for component testing using a test strip according to claim 1, wherein the concentration of the target component is determined based on the digital signal value of one specific element among the four elements.