JPH0672848B2 - Chemical analysis method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a chemical analysis method for quantitatively analyzing a specific component in a fluid by utilizing an optical change such as colorimetric analysis, and particularly to a stable light amount and a stable light amount. The present invention relates to a chemical analysis method capable of obtaining a measured photometric value.

(Prior Art) Color development caused by reaction between a substance to be detected and an appropriate reagent in order to detect a specific substance existing in a liquid,
A method utilizing an optical change such as discoloration is a very general method and is called colorimetric analysis. As a method of this colorimetric analysis, there are a wet method and a dry method. In the wet method, a reagent that reacts with a specific test substance to cause an optical change such as color development is added to a sample solution. On the other hand, in the recently developed dry method, a liquid sample is dropped on an analytical element containing a reagent, and the color developed by the reaction between the test substance and the reagent is measured.

When the reagent is added to the reagent solution or the sample solution is spotted on the dry analytical element, the reagent and the test component react with each other to form a dye or the like. For example, when blood or plasma is spotted on a dry analytical element as described in JP-A-55-164356, the reagent in the analytical element reacts with glucose in the sample, and a dye,
For example, a red pigment is formed. Since the optical density of this cyclic analytical element reacts with the amount of the produced dye, the reflection optical density is measured after a certain period of time, and the glucose concentration is calculated from a calibration curve showing the relationship between the glucose content and the optical density, which is obtained in advance, That is, it is converted into a blood glucose level. In the cyclic method, the measurement is performed by the reflected light from the analytical element, whereas in the wet method, the optical density is measured by the transmitted light.

However, in the conventional analysis method described above, except for the case of the analysis by the reaction rate method in which the activity of an enzyme or the like is measured using the reaction rate as a scale, the optical density measurement is performed after a fixed time from the spotting of the sample solution or the addition of the reagent. Was only. Therefore, when the concentration of the test component is low, the reaction has already been completed before the elapse of the certain period of time, and it is not necessary to wait until this time, which is a waste of time. On the other hand, when the concentration of the test component is high, when the reaction time is short, the slope of the calibration curve is small, the coefficient of variation of the analytical value is large, and sufficient analytical accuracy is often not obtained.

To solve this problem, the applicant of the present invention filed Japanese Patent Application No. 61-205.
There is a proposal filed by No. 604. This proposal tracks the change in optical density by measuring the optical density multiple times at an appropriate time interval after the start of the reaction, and determines from the value of the optical density at each measurement point whether the reaction should be continued or not. If it is judged that it is not necessary to continue the reaction from the viewpoint of accuracy, select the calibration curve corresponding to the reaction time,
When it is determined that the reaction should be continued, the reaction is further continued, and the analysis is completed in a minimum reaction time from the viewpoint of analysis accuracy.

(Problems to be Solved by the Invention) However, according to the above proposal, the photometric time can be shortened by switching the calibration curve, but the light source that emits the measurement light is continuously turned on during the photometry, and Even in the standby mode, which was not performed, the voltage was turned on at about 60% of the metering level. For this reason, there is a problem that the amount of heat generated by the light source lamp increases and the temperature of the constant temperature part that keeps the slide at a constant temperature rises above a predetermined temperature to cause a measurement error. In addition, the case where the light source lamp is turned off after being turned off for a long time and turned on after being turned off for a short time
As shown in FIGS. 5A and 5B, there is also a problem that the light quantity of the lamp, especially the rising light quantity, changes.

The present invention solves the above problems, can prevent heat generation of a light source lamp, can prolong the life of the lamp, and can obtain a stable amount of light, and can perform accurate quantitative analysis of a substance to be measured. The purpose is to provide.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides a chemical analysis slide in which a substance to be measured is dripped and supplied on a reagent layer, which is kept at a constant temperature for a predetermined time and then emitted from a light source to the slide. The amount of reflected light from the slide is measured by irradiating the measured light, and when performing quantitative analysis of the substance to be measured by obtaining the reflected optical density of the slide, prior to the measurement of the amount of reflected light from the slide. The light source is temporarily turned on, and the light source is turned on again after a lapse of a predetermined turn-off time to measure the reflection optical density from the slide.

(Operation) According to the above method, the light source that emits the measurement light is turned off while the reflection optical density is not being measured, so it is possible to suppress the heat generation of the light source lamp and prevent the temperature rise of the constant temperature part.
The measurement accuracy can be improved. In addition, the light source lamp is temporarily turned on before the measurement, then turned off for a predetermined time and then turned on again, so that the rising light amount of the light source lamp becomes constant,
Stable light quantity is obtained and accurate reflection optical density is obtained,
Accurate chemical analysis can be performed.

(Example) Hereinafter, one example of the chemical analysis method according to the present invention will be described with reference to the drawings.

The configuration of the apparatus used in this embodiment will be described with reference to the measuring section shown in FIG. 3 and the block diagram shown in FIG. A chemical analysis slide 1 having a chemical analysis film 1b on the surface of which a reagent layer composed of an analysis element containing a reagent is formed, and a substance to be measured is supplied dropwise to the reagent layer, is held by a current supplied to a thermostat 20. It is kept at a constant temperature on the member 10 for a predetermined time (for example, 37 ° C x 2
6 minutes). As a result, the reagent of the film 1b acts on the substance to be measured to cause a color reaction. A cover constant temperature part 20a is arranged above the constant temperature part 20 to facilitate keeping the constant temperature of the slide 1 by pressing the spotting surface of the slide 1 from above, and the liquid sample spotted on the slide 1. It is designed to prevent the evaporation of. The constant temperature cover 20a is kept at a predetermined temperature by a heater and a temperature adjustment sensor (not shown).

The light source lamp 28 emits measurement light over a relatively wide wavelength range, but since the color development wavelength of the chemical analysis slide 1 differs depending on the type of chemical analysis slide and the substance to be measured, it is above the light source lamp 28. Optical filter 30 is installed in
The optical filter 30 is used to select measurement light in an effective wavelength range and utilize it for the above measurement. Further, as described above, the temperature of the chemical analysis slide 1, which is kept at a constant temperature by the heat insulating filter 31 provided between the light source lamp 28 and the optical filter 30, is raised by the heat from the light source lamp 28, or this heat is generated. It is designed to prevent the characteristics and life of the optical filter 30 from being adversely affected. A black plastic disc 10B and a white ceramic plate 10W as reference concentration plates are embedded in two places on the lower surface of the holding portion 10a of the slide holding member 10, and the swing direction of the slide holding member 10 (direction of arrow). In this order, they are arranged at a predetermined interval.

The constant temperature part 20 has an opening in which a transparent glass plate is fitted in the center part.
27, and both ends are fixed to the support plate 12 with screws 20b.

Below the constant temperature part 20, a photometric part 21 having an optical system extending vertically toward the opening 27 is arranged. The photometric unit 21 is an outer lens barrel 21a having a light receiver 29 fixed to the upper outer edge portion and an optical filter 30 fixed to the upper inner edge portion, and an inner lens barrel 21b screwed to the inner side of the outer lens barrel and having a heat insulating filter 31 fixed to the upper portion. ,
Also, a light source lamp 28 is provided inside the inner lens barrel. Further, the height position of the light source lamp 28 is adjusted to a predetermined height by the hexagon socket set screw 21c.

In the photometry unit 21, the measurement light emitted from the light source lamp 28 made of a tungsten lamp is reflected on the lower surface of the film 1b of the slide 1, and the reflected light is detected by the light receiver 29 made of a photodiode. . The amount of reflected light detected in this way is inputted to the amplifier 13, the A / D converter 14, and the central control unit (CPU) 16 and stored therein. Similarly, the white board 10W and the blackboard 10B have openings 27 of the constant temperature section 20.
The measurement is performed by the measuring unit 21 even when it is directly faced with, and the amount of reflected light is input to and stored in the CPU 16 as the reference amount of reflected light. Further, the central control unit (CPU) controls on / off of the light source lamp 28 via the light source lamp on / off driver 15.
The concentration of the substance to be measured, which will be described later, is calculated based on a calibration curve stored in a ROM card (not shown) as a storage unit and displayed on the display unit 17. The slide holding member
Reference numeral 10 designates the slide 1 at the spotting position A by a driving means (not shown),
It is designed to be moved to a white plate position B, a blackboard position C, and a slide photometric position D.

A typical process for performing reflection optical density measurement by the apparatus configured as described above will be described with reference to the time chart shown in FIG. 1 and the flow chart shown in FIG.
A calibration curve showing the relationship between the concentration of the substance to be measured and the optical density is created in advance for each reaction time and stored in the CPU 16. At the spotting position A, the substance to be measured is dropped and supplied onto the film 1b of the chemical analysis slide 1 mounted on the slide 1, and photometry is started in step (a). Next, in step (b), slide 4 to the spotting position A.
Then, the light source lamp 28 is lit for 1.3 seconds and then turned off again for 2.4 seconds. Next, in step (c), slide 1 on a white plate.
Move to position B of 10W, turn on the light source lamp 28 for 1.3 seconds, perform whiteboard photometry for measuring the optical density of the whiteboard 10W for 0.3 seconds,
It is stored in the CPU 16. Next, in step (d), similarly, blackboard photometry is performed at the blackboard position C (blackboard 10B is located at the opening 27 of the constant temperature part 20). The white plate photometry and the blackboard photometry are preliminary reference photometry for switching the calibration curve, which will be described later, and are necessary to complete the measurement in the minimum necessary time according to the density value.

Next, in step (e), the slide holding member 10 is moved to the slide photometric position D (the slide 1 is located above the opening 27), and two minutes after the spotting, the light source lamp 8 is set to 1.
It lights for 3 seconds, and slide metering is performed for 0.3 seconds within this lighting time. At this time, the sample layer is kept at a predetermined temperature by the upper and lower heat retaining members 20, 20a while the slide 1 is at the slide photometric position. Then in step (f),
When the optical density value measured at this time is smaller than the optical density value stored in the CPU 16 after 2 minutes and stored in the CPU 16, the reaction is terminated and the slide 1 is discharged from the slide photometric position D, while the reaction time 2 The concentration of the substance to be measured is calculated using a calibration curve prepared in minutes. This calibration curve is not shown in ROM
It is selected from the ones stored in the card by a command signal from the arithmetic and control unit in the CPU 16 and is input to the arithmetic unit in the CPU 16 for use in arithmetic. The calibration curve stored in this ROM card can be replaced with this ROM card according to the type of the substance to be measured. Also this ROM
Instead of using the card, the calibration curve may be stored in the storage unit in the CPU 16.

If the optical density after 2 minutes is higher than the set value, slide 1 is placed at the slide measurement position for 2.5 minutes to continue the reaction, and in step (g), the light source lamp 28 is turned on again for 1.3 seconds, and then step (e) ) And (f), the same photometry is performed. Then, in step (h), the value of the optical density measured at this time is preset and stored in the CPU 2.5.
When the value is less than the optical density after the minute, the reaction is stopped and the slide 1 is discharged from the slide photometric position, while the concentration of the substance to be measured is calculated using the prepared calibration curve at the reaction time of 2.5 minutes.

Similarly, the photometry after 3 minutes in steps (i) and (j),
Photometry after 3.5 minutes in steps (h) and (l), photometry after 4.5 minutes in steps (m) and (n), 6 in step (o)
After a minute, perform photometry. Then, 2.4 seconds after the completion of the final photometry in each step, the slide 1 is moved again to the position B of the white plate 10W, and in step (p), the light source lamp 28 is turned on for 1.3 seconds and the white plate photometry for measuring the optical density of the white plate 10W is 0.3.
Perform for 2 seconds and input to CPU16. Next, in step (q), blackboard photometry is similarly performed. The concentration of the substance to be measured is calculated using the calibration curve corresponding to each reaction time stored in the CPU 16 in step (r) based on the reference photometric value by the white plate photometry and the blackboard photometry and the final photometric value of the sample. To do. Finally, in step (s), the concentration of the substance to be measured is displayed on the display unit 17.

According to the present embodiment, since the light source lamp 28 is turned off when the metering is not performed, it is possible to prevent heat generation by the lamp, and it is possible to prevent the temperature rise of the constant temperature section 20, 20a that holds the slide at a constant temperature. The measurement accuracy can be improved.
Further, since the light is turned off for a certain period of time before each photometry, it is possible to prevent the fluctuation of the lamp light quantity due to the length of the light-off time, especially the change of the light quantity at the time of rising. Since the time interval t ₂ between the final sample photometry and the white plate photometry is set to be the same as that at the first time, a stable optical density can be obtained even for the reference photometry, and the final sample photometric value indicates the measured substance The accuracy when calculating the concentration is improved. Moreover, the measurement can be completed in the minimum necessary time.

It should be noted that the turn-off and turn-on times shown in the above-mentioned examples show the times in a typical process, and are not limited to these.

(Effects of the Invention) As described above, according to the present invention, the light source is temporarily turned on prior to the measurement of the amount of reflected light from the slide, and the light source is turned on again after a lapse of a predetermined turn-off time. Since it was designed to measure the reflection optical density, it was possible to prevent the light source lamp from generating heat and prevent the temperature of the constant temperature part from rising, and a stable amount of light was obtained and spotted on the analytical element on the slide. Accurate chemical analysis of the substance to be measured can be performed.

[Brief description of drawings]

FIG. 1 is a time chart showing one embodiment of the chemical analysis method according to the present invention, FIG. 2 is the same flow chart, and FIG. 3 is a sectional view of the measuring part of the apparatus used for the chemical analysis according to this embodiment. FIG. 5 is a schematic block diagram of an apparatus according to the method of the present invention, and FIG. 5 is a graph showing the relationship between the turn-off time and the light amount of the light source lamp. 1 …… Slide 1b …… Chemical analysis film (reagent layer) 28 …… Light source lamp 29 …… Receiver

Claims (3)

[Claims] 1. A chemical analysis slide, to which a substance to be measured is dropped and supplied on a reagent layer, is kept at a constant temperature for a predetermined time, and then the measurement light emitted from a light source is irradiated to the slide to measure the amount of light reflected from the slide. Then, in the chemical analysis method for quantitatively analyzing the substance to be measured by obtaining the reflection optical density of the slide, the light source is temporarily turned on before the measurement of the amount of reflected light from the slide, and a predetermined turn-off time elapses. After that, the light source is turned on again and the reflection optical density from the slide is measured. 2. The light source is turned on after the lapse of the predetermined turn-off time, the reflection optical density from the reference density plate is measured before the reflection optical density from the slide is measured, and then the reflection optical density from the slide is measured. The chemical analysis method according to the above item 1, wherein the optical density is measured. 3. The reflection optical density of the reference concentration plate is measured after the reflection optical measurement from the slide, and the measurement result is based on the calibration curve of the substance to be measured stored in the storage means and the measurement result. 3. The chemical analysis method according to claim 1 or 2, wherein the substance concentration of the substance is calculated.