JP2001074649A - Method for measuring angle of optical rotation, and method for inspecting urine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an angle-of-optical rotation measuring method that is capable of measurement quickly, stably, and accurately by excluding influence caused by noise being mixed by bubbles, particles, or the like. SOLUTION: In the method for measuring the angle of optical rotation where light is applied to a sample to be inspected containing a natural substance and optical rotation being generated due to the natural optical activity substance when light is transmitted through the sample to be inspected, polarization with a known vibration surface is applied to the sample to be inspected while performing the small vibration of the vibration surface by a modulation signal with an angular frequency of ω, a component with a specific vibration surface out of polarization through the sample to be inspected is detected by a photosensor, a component where the angular frequency is ω is extracted out of the output signals of the photosensor by phase-sensitive detection with a modulation signal as a reference signal, and the angle of the optical rotation by the sample to be inspected is calculated based on at least three sets of data including the relative angle formed by the vibration surface of light that enters the sample to be inspected and that of light being detected by the photosensor, and the intensity of the component where the angular frequency obtained at the relative angle is ω.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical rotation angle measuring method and a urine test method used for identification of a solute of a solution, purity test, concentration determination and the like.

[0002]

2. Description of the Related Art A polarimeter is used as a polarimeter for detecting the concentration of an aqueous solution of fructose, sucrose, glucose or the like. In addition, since it is possible to test the concentration of optically rotatory substances such as glucose and protein in urine, it is expected to be widely used as a urine test apparatus that does not require consumables such as test paper.

FIG. 6 shows an example of a conventional polarimeter. This optical rotation meter is based on the optical rotation angle (so-called compensation value) of the magnetic rotation when the optical rotation generated by the natural optical rotation substance in the test sample is canceled out (compensated) by the optical Faraday effect, that is, the magnetic rotation. , The magnitude of the natural optical rotation, that is, the optical rotation angle. The semiconductor laser module 21 including a sodium lamp, a band-pass filter, a lens, a slit, and the like projects substantially parallel light including a D line of sodium having a wavelength of 589 nm. Polarizer 23
Transmits only a component having a specific vibration surface out of the projection light of the semiconductor laser module 21. The sample cell 25 holding the test sample has a pair of transparent transmission surfaces facing each other, and is arranged such that light projected by the semiconductor laser module 21 passes through the inside. Analyzer 26
Transmits only a component having a specific vibration surface out of the light transmitted through the sample cell 25. Here, the relative angle Θ between the transmission axis of the polarizer 23 and the transmission axis of the analyzer 26 is
It is fixed to π / 2. The optical sensor 27 detects a component of the projection light of the semiconductor laser module 21 that has passed through the analyzer 26. The Faraday cell 24 includes the signal generator 3
Based on the modulation signal output by the control signal 0 and the control signal output by the computer 22, the vibration surface of the light projected by the semiconductor laser module 21 is modulated and controlled. The Faraday cell 24 is driven by a Faraday cell driver 29. The lock-in amplifier 28 performs phase-sensitive detection of the output signal of the optical sensor 27 using the modulated signal output by the signal generator 30 as a reference signal. The computer 22 calculates the angle of rotation of the test sample contained in the sample cell 25 based on the control signal and the output signal of the lock-in amplifier 28. As described above, by sweeping the angle of the vibrating surface using the Faraday cell, simplification and downsizing can be achieved as compared with an apparatus using other vibrating surface modulating means.

Hereinafter, the principle of the conventional polarimeter will be described. The Faraday cell 24 includes the semiconductor laser module 2
1 modulates the vibration plane of the light transmitted through the polarizer 23 with amplitude = δ and angular frequency = ω. At this time, the optical sensor 2
The intensity I of the light reaching 7 is represented by the following equation (1).

I = T × I ₀ × {cos [Θ−α + β + δ × sin (ω × t)]} ² (1) where T: transmittance of the test sample I ₀ : incident light on the test sample Intensity ：: Relative angle between transmission axis of polarizer 23 and transmission axis of analyzer 26 α: Optical rotation angle by test sample β: Rotation angle of light by Faraday cell 24 t: Time

The sample cell 25 and the analyzer 26
Are ignored. Since the relative angle の between the transmission axis of the polarizer 23 and the transmission axis of the analyzer 26 is π / 2, the following equation (2) is derived from the equation (1).

I = T × I ₀ × {sin [β−α + δ × sin (ω × t)]} ² (2)

When β−α = 0, that is, assuming that the optical rotation angle due to the test sample is canceled out (compensated) by the rotation angle due to the Faraday cell 24, the equation (2) becomes the following equation (3). It is represented by

I = (1/2) × T × I ₀ × {1-cos [2 × δ × sin (ω × t)]} = (1/2) × T × I ₀ × {1- [J ₀ (2 × δ) + 2 × J ₂ (2 × δ) × cos (2 × ω × t) +...] (3) where J _n (x) is an n-order Bessel function. .

Equation (3) shows that the light intensity I detected by the optical sensor 27 does not include the frequency component ω of the modulated signal alone. Assuming that the rotation angle and the amplitude of modulation by the test sample are small, that is, | β−α | ≪1 and δ≪1, Equation (3) is approximated to Equation (4) below.

I ≒ T × I ₀ × (β−α + δ × sin (ω × t)) ² = T × I ₀ × ｛(β−α) ² + 2 × (β−α) × δ × sin (ω × t) + [δ × sin (ω × t)] P ² ＝= T × I ₀ × ｛(β−α) ² + 2 × (β−α) × δ × sin (ω × t) + ｛δ ² / 2 × [1-cos (2 × ω × t)]｝｝ (4)

From this, it can be seen that the output signal I of the optical sensor 27 contains angular frequency components of angular frequency 0 (DC), ω, and 2 × ω. When this I is phase-sensitive detected by the lock-in amplifier 28 using the modulated signal as a reference signal, a component having an angular frequency of ω, that is, a signal S represented by the following equation (5) can be extracted.

S = T × I ₀ × 2 × (β−α) × δ (5)

This signal S becomes zero only when β = α. This point is the extinction point. Β when the vibration surface of the light is rotated by the Faraday cell 24, that is, β is swept, and S becomes zero corresponds to the optical rotation angle α.
The same applies to the case considered in equation (3). When I is phase-sensitive detected, the output I of the optical sensor 27 becomes zero when β = α.

As described above, by modulating the angle of the oscillating surface of light, only the signal S of the modulation frequency component is separated from noise such as light source intensity, power supply fluctuation, and radiation.
The signal can be selectively extracted, and a signal having a high S / N ratio can be obtained. The extinction point can be accurately found from the signal S, and the optical rotation angle α can be obtained with high accuracy.

However, in the optical rotation angle measurement, it is necessary to detect the output signal of the lock-in amplifier 28 while continuously changing β at a small angular velocity so that the signal S becomes zero. Therefore, many measurement points are required, and a long time is required for measurement even by automation. When feedback control is performed based on the measured value at each measurement point, if bubbles, particles, and the like are present on the optical path of the transmitted light in the sample cell 25, the measured value fluctuates and an appropriate loop can be constructed. And a longer measurement time was required.

[0017]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and can eliminate the influence of noise mixed in by bubbles or particles, and can stably and accurately measure in a short time. It is an object of the present invention to provide an optical rotation angle measuring method and a urine test method that can perform the method.

[0018]

As is apparent from the above equation (5), in the vicinity of the extinction point, the relative intensity between the intensity of the component having an angular frequency of ω and the transmission axis of the polarizer and the transmission axis of the analyzer. The relationship with the angle is represented by a linear function. In the present invention,
Applying this principle, the extinction point is obtained from a linear regression equation (regression line) obtained from the intensity of the component of three or more different relative angles different from each other and the angular frequency at that time. Specifically, as a first embodiment of the present invention, light is incident on a test sample containing a natural optically rotating substance, and when the light passes through the test sample, the natural optically rotating substance is applied to the sample. A method for measuring an optical rotation angle generated due to an optical rotation, wherein (a) a polarized light having a known vibration surface is incident on the test sample while slightly vibrating the vibration surface by a modulation signal of an angular frequency ω. (B) detecting, by an optical sensor, a component having a specific vibration plane out of the polarized light transmitted through the test sample, and (c) performing phase-sensitive detection using the modulation signal as a reference signal to perform the light detection. Extracting a component having an angular frequency of ω from the output signal of the sensor; and (d) a relative angle between a vibration surface of light incident on the test sample and a vibration surface of light detected by the optical sensor, and a relative angle between the vibration surface and the vibration surface. Said angle obtained at an angle Calculating a rotation angle of the test sample based on three or more sets of data including the intensity of the component having a frequency of ω.

In the step (a), it is effective to change the relative angle by continuously rotating the vibration plane of the polarized light incident on the test sample. Also,
In step (a), it is also effective to change the relative angle by discretely changing the vibration plane of the polarized light incident on the test sample. In step (d), a first-order regression equation is created based on the data, using the relative angle as a reference variable and the intensity of the component whose angular frequency is ω as a dependent variable, and based on the obtained regression equation. It is effective to calculate the optical rotation angle of the test sample by the above method. In the step (a), it is effective to change the relative angle by rotating the vibration plane of the polarized light incident on the test sample by the optical Faraday effect.
Further, in the step (d), based on the data, the magnitude of the magnetic field for obtaining the relative angle or the amount of current for generating the magnetic field is used as a reference variable, and the intensity of the component whose angular frequency is ω It is effective to create a first-order regression equation with as a dependent variable, and calculate the optical rotation angle of the test sample based on the obtained regression equation.

Further, according to a second embodiment of the present invention, light is incident on a test sample containing a natural rotatory substance and a magnetic rotatory substance, and a magnetic field is applied to the test sample. The vibrating surface of the light passing through the test sample is rotated by the optical Faraday effect, and the optical rotation caused by the natural optical rotation material when the light passes through the test sample is generated by applying the magnetic field. A method for measuring an optical rotation angle based on the magnitude of rotation of light, comprising: (a) applying a polarized light having a known vibration surface to a test sample while slightly vibrating the vibration surface with a modulation signal having an angular frequency ω; (B) detecting, by an optical sensor, a component having a specific vibration plane in the polarized light transmitted through the test sample, and (c) phase-sensitive detection using the modulation signal as a reference signal. Previous Extracting a component having an angular frequency of ω from the output signal of the optical sensor; and (d ′) extracting the magnitude of the magnetic field and data containing the intensity of the component having an angular frequency of ω obtained at the magnitude of the magnetic field. Calculating a rotation angle of the test sample based on the three or more sets.

In the step (a), it is effective to continuously rotate the light vibrating surface by the optical Faraday effect. In step (a), it is also effective to discretely change the vibration surface of the light by the optical Faraday effect. Further, in step (d ′), based on the data, the magnitude of the magnetic field or the amount of current for generating the magnetic field is used as a reference variable, and the intensity of the component whose angular frequency is ω is used as a dependent variable. It is effective to create a first-order regression equation and calculate the optical rotation angle of the test sample based on the obtained regression equation.

Further, in the optical rotation angle measuring method, it is effective to calculate the regression equation using the least square method. It is also effective to further include a step of determining that the measurement is valid when the reliability of the regression equation is higher than a predetermined value. At this time, the indicator of evaluation of the reliability, the angle obtained by substituting data corresponding residual sum of squares S _E shown in the following equation, the residual sum of squares S _E to the reference variable of the regression equation It is effective to use the value D or the correlation coefficient R divided by the sum of the squares of the intensity values of the components having the frequency ω.

[0023]

(Equation 2)

Further, according to the method for measuring the optical rotation angle described above, it is possible to provide a urine test method for effectively detecting the concentration of a natural optical rotation substance in urine when urine is used as a test solution.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION The first optical rotation angle measuring method of the present invention is to cause light to enter a test sample containing a natural optical rotation substance, and to cause the light to pass through the test sample due to the natural optical rotation substance. An optical rotation angle measuring method for measuring the optical rotation generated by the method, wherein a polarized light having a known vibration surface is incident on a test sample while the vibration surface is slightly vibrated by a modulation signal of an angular frequency ω; (B) detecting, using an optical sensor, a component having a specific vibration plane out of polarized light transmitted through the test sample, and performing phase-sensitive detection using a modulation signal as a reference signal, thereby obtaining the above-described expression in the output signal of the optical sensor. (C) extracting the component having the angular frequency ω shown in (5), and the relative angle between the vibration plane of the light incident on the test sample and the vibration plane of the light detected by the optical sensor and the relative angle The angular frequency obtained is strong at the component of ω Based on the three or more sets of data, including, it comprises a step (d) for calculating the angle of rotation due to a test sample.

First, in the present invention, the relative angle between the vibration surface of light incident on the test sample and the vibration surface of light detected by the optical sensor, and the intensity of the component whose angular frequency detected at that time is ω A linear regression equation expressing these relationships is created from the data consisting of Then, the optical rotation angle of the test sample is calculated using the linear regression equation. Of course, it is not necessary to use the relative angle directly, and when rotating the vibration surface of the incident light on the test sample by the optical Faraday effect, that is, magnetic rotation, instead of the relative angle, the magnetic field for obtaining the relative angle is used. The magnitude or amount of current for generating the magnetic field may be used. When the magnitude of the magnetic field and the amount of current when the extinction point appears are known, the angle of rotation due to the test sample can be easily calculated using a known formula. The relative angle between the vibration surface of the light incident on the test sample and the vibration surface of the light detected by the optical sensor is changed by rotating one of the vibration surfaces. For example, the vibrating surface of the incident light is continuously rotated. In addition, since continuous measurement is not required in the present invention, the vibration surface of incident light may be changed discretely. According to the present invention, it is not necessary to continuously change β shown in the above equations, so that the circuit configuration can be simplified. Further, since it is not necessary to directly determine the extinction point, the concentration range of the test sample can be set large.

Further, the present invention described above relates to a measuring method in which a magnetic field is directly applied to a test sample, and an optical rotation angle is obtained based on the magnitude of magnetic rotation due to the optical Faraday effect of the magnetic rotatory substance in the test sample. Can also be applied. That is, the second optical rotation angle measurement method of the present invention transmits light to a test sample containing a natural optical rotation substance and a magnetic rotation substance and transmits the test sample by applying a magnetic field to the test sample. Rotating the vibrating surface of the rotating light by the optical Faraday effect, and measuring the optical rotation caused by the natural optical rotation material when the light passes through the test sample, based on the magnitude of the rotation of the light due to the application of the magnetic field Optical polarization angle measuring method, wherein a polarized light having a known vibration surface is incident on a test sample while the vibration surface is slightly vibrated by a modulation signal having an angular frequency ω (a).
(B) detecting, using an optical sensor, a component having a specific vibration plane out of the polarized light transmitted through the test sample, and performing phase-sensitive detection using the modulation signal as a reference signal to obtain an angle of an output signal of the optical sensor. Step (c) of extracting a component having a frequency of ω, and an optical rotation angle of the test sample is calculated based on three or more sets of data including the magnitude of the magnetic field and the intensity of the component having the ω component. Step (d ')
And Here, from the combination of the magnitude of the magnetic field or the amount of current and the intensity of the component whose angular frequency is ω, a first-order regression equation with one variable as the other variable is created, and the test sample is determined based on the obtained regression equation. Can be calculated. For example, a linear regression equation is calculated in which the magnitude of the magnetic field or the amount of current for generating the magnetic field is used as a reference variable, and the intensity of the component having an angular frequency of ω as a dependent variable is calculated. Calculate the optical rotation angle by the test sample.
Here, the magnitude of the rotation of the light due to the optical Faraday effect is changed continuously or discretely.

In calculating the above regression equation, for example,
Use multiplication. The reliability of the regression equation is evaluated using the residual sum of squares S _E shown in the following equation (6) as an index, and when it is lower than a predetermined value, it is determined that the obtained optical rotation angle is valid. Then, a more reliable measurement can be performed by eliminating the determination result affected by the noise. Further, as for the correlation function R shown in the equation (7), a value closer to 1 eliminates a determination result affected by noise, thereby enabling more reliable measurement. Further, as shown in the equation (8), the residual sum of squares S _E is the square of the value of the dependent variable (ie, the calculated value of the signal S) obtained by substituting data corresponding to the reference variable of the regression equation. By using the value D divided by the sum of the above, the influence of the light transmittance of the sample cell and the like can be eliminated.

[0029]

(Equation 3)

By increasing the number of measurement points,
The effect of noise mixed into the signal can be reduced. In particular, when a large number of measurement points are provided, for example, the data can be collated with the regression equation calculated based on the data acquired so far for each measurement point, and the data at that measurement point can be determined. The optical rotation angle measuring method of the present invention can be applied to a urine test in which urine is used as a test sample and the concentration of a natural optical rotation substance such as glucose or albumin contained therein is detected.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings.

Embodiment 1 FIG. 1 shows a schematic configuration of a polarimeter of the present embodiment. The semiconductor laser module 1 projects substantially parallel light having a wavelength of 780 nm and an intensity of 3.0 mW. The polarizer 3 transmits, out of the light projected by the semiconductor laser module 1, only a specific polarization component having a vibration plane coincident with its transmission axis, for example, only a component having a vibration plane parallel to the paper surface. After the polarizer 3, a Faraday cell 4
Is arranged. The Faraday cell 4 includes a light-transmitting core material made of, for example, flint glass, and a solenoid coil that generates a magnetic field in a traveling direction of light propagating through the core material. The Faraday cell driver 9 superimposes a control signal for generating a magnetic field on the Faraday cell 4 with a modulation signal for modulating the generated magnetic field, and outputs the resultant signal to the Faraday cell 4. The Faraday cell 4 generates a magnetic field according to a signal from the Faraday cell driver 9 and rotates the vibration surface of light passing therethrough by the optical Faraday effect.

The sample cell 5 containing the test sample is arranged such that the light projected from the semiconductor laser module 1 and transmitted through the polarizer 3 and the Faraday cell 4 passes through the inside. The effective optical path length of the sample cell 5 is 5
0 mm. The analyzer 6 is arranged in a so-called orthogonal Nicol state with the polarizer 3, and selectively transmits light having a component whose vibration plane is orthogonal to that of the light transmitted through the polarizer 3. The optical sensor 7 detects light transmitted through the analyzer 6. The preamplifier 8 amplifies the output of the optical sensor 7 and outputs it to the lock-in amplifier 11. The signal generator 10 outputs a modulation signal to the Faraday cell driver 9. Lock-in amplifier 1
1 uses the modulated signal output to the Faraday cell 4 as a reference signal, performs phase-sensitive detection on the output signal of the preamplifier 8, and outputs the signal S represented by the equation (5) to the computer 12.
The computer 12 outputs a control signal to the Faraday cell driver 9 and calculates an optical rotation angle based on an output signal of the lock-in amplifier 11.

Using the above polarimeter, pure water and a concentration of 1
The optical rotation angle of the 000 mg / dl glucose aqueous solution was measured. The control current supplied to the Faraday cell 4 is-
While sweeping from 0.06A to 0.06A in 60 seconds,
A modulation current having a frequency of 1.3 kHz and an amplitude of 0.001 A was superimposed on this. At this time, the relationship between the control current and the output of the lock-in amplifier 11, that is, the signal S is shown by a solid line (pure water) and a broken line (glucose aqueous solution) in FIG. In the case of pure water, since no optical rotation is exhibited, the output of the lock-in amplifier 11 becomes zero when the injection current to the Faraday cell is 0 A, and in the case of a glucose aqueous solution having the above concentration, the output is 0.051 A. Sometimes the output is preset to zero. Since the control current is supplied to the solenoid coil of the Faraday cell 4 and forms a magnetic field, the magnitude of the rotation of the vibrating surface appearing in the light transmitted through the Faraday cell 4 at this current value depends on the natural optical rotation. It corresponds to the optical rotation angle (magnitude of natural optical rotation) due to the substance.

Here, the time constant of the lock-in amplifier 11, that is, the integration time of the detection signal was set as follows.
First, the time constant is set to about 3 ms, which is sufficiently shorter than the sweep time and longer than the cycle of the modulation signal, and the control current is swept to control the control current and the lock-in amplifier 1 as shown in FIG.
Thus, a linear characteristic curve showing the relationship with the output signal S is obtained. Next, while gradually increasing the time constant and obtaining the same relationship, the time constant of 100 milliseconds immediately before it deviated from the previously obtained curve was used in the following measurements. Here, deviating means that the slope of the curve becomes small. Through these steps, the highest S / N ratio can be achieved with respect to the time required for the sweep.

The characteristic curve indicating the relationship between the control current and the signal S is a straight line in principle as shown in the equation (5). No. When the control current at the time when the signal S becomes zero is read from the actually obtained characteristic curve, the control current is 0.0
02A, and 0.05 A in an aqueous glucose solution.
Becomes That is, an error due to the mixing of noise is recognized. Table 1 shows the signals S when the control current is -0.04A, 0 and 0.04A.

[0037]

[Table 1]

Here, assuming that the control current is a reference variable X and the signal S is a dependent variable Y, the regression lines shown in equations (9) and (10) are obtained for the pure water and the aqueous glucose solution by the least square method. Is obtained.

Pure water: Y = 0.00333 + 20 × X (9) Glucose aqueous solution: Y = −1.01 + 19.9 × X (10)

When X when Y becomes zero is obtained from the obtained regression line, -0.000167 in the case of pure water.
A, and in the case of an aqueous glucose solution, 0.0508 A
Becomes In this way, the obtained value is closer to a true value set in advance than the value obtained by directly reading the extinction point. From the regression line shown in equation (9) and the data in pure water shown in Table 1, these residual sums of squares are 3.27 ×
It becomes ^10-3 . Also, the regression line shown in equation (10) and Table 1
According to the data of the glucose aqueous solution shown in FIG. 1, the sum of the residual squares is 1.22 × 10 ⁻² .

Table 2 shows data when a large noise is mixed in the signal when the optical rotation angle of the aqueous glucose solution is measured.

[0042]

[Table 2]

In Table 2, when the control current is -0.04 A, noise is mixed. The regression line obtained using this data is represented by the following equation (11).

Y = −1.08 + 22.4 × X (11)

According to the equation (8), the control current X when the output signal S of the lock-in amplifier 11 indicated by Y becomes zero.
Becomes 0.0482A. When this is compared with the set value, it is apparent that the calculated value is affected by noise.
The residual sum of squares at this time is 8.62 × 10 ⁻² . This value is clearly larger than the value obtained using the data in Table 1, and is less adaptable to the regression line. Therefore, the residual sum of squares is used as an index for evaluating the reliability of the regression equation, that is, the degree of matching between the regression equation and the measured data. For example, if this value is larger than a predetermined value, it is determined that the error factor included in the measurement data, that is, noise exceeds the allowable amount, the measurement is invalidated, and the measurement is performed again, so that high measurement accuracy is secured. In the above glucose aqueous solution, when the residual sum of squares is larger than, for example, 2.0 × 10 ⁻² , the measurement may be invalidated.

Embodiment 2 FIG. 3 shows a polarimeter of this embodiment. In the polarimeter of this embodiment, the projection light of the semiconductor laser module 1 is magnetically rotated by a solenoid coil 20 wound around a sample cell 15 instead of the Faraday cell 4 used in the polarimeter of the first embodiment. Sample cell 1
The actual optical path length of No. 5 is 50 mm as in the first embodiment. The driver 19 outputs a control current on which a modulation signal is superimposed to the solenoid coil 20, similarly to the Faraday cell driver 9 used in the first embodiment. Other components are
Functions similarly to those of the polarimeter of the first embodiment.

Using the polarimeter of this embodiment, pure water and concentrations of 1000 mg / dl and 20
The optical rotation angle of a 00 mg / dl glucose aqueous solution was measured. As a standard, in the case of pure water that does not show optical rotation, the injection current into the solenoid coil 20 is 0.0
At the time of 2A, in the case of a glucose aqueous solution having a concentration of 1000 mg / dl, when the concentration is 1.01A, the concentration is 2000 m
In the case of the glucose aqueous solution of g / dl, the output signal of the lock-in amplifier 11, that is, the signal S shown in the equation (5) was set to be zero at 2.00 A.

First, discretely at intervals of 1.5 A every second-
A control current changed to 1.5 A, 0, and 1.5 A was supplied to the solenoid coil 20 after a modulation signal having an amplitude of 0.001 A and a frequency of 1.3 kHz was superimposed thereon.
The time constant of the lock-in amplifier 11 was set to 100 milliseconds. Note that the stable output signal of the lock-in amplifier 11 after one second from the start of the supply of the control current at each current value was defined as a signal S for the control current. The results are shown in FIG.

[0049]

[Table 3]

Here, each straight line in FIG. 4 is a regression line obtained by the least-squares method, and the control current is represented by a reference variable X,
Assuming that the signal S is a dependent variable Y, regression lines for these test samples are expressed by the following equations (12), (13), and (14), respectively.

Pure water: Y = 0.00867 + 0.198 × X (12) Glucose aqueous solution (1000 mg / dl): Y = −0.193 + 0.196 × X (13) Glucose aqueous solution (2000 mg / dl): Y = − 0.368 + 0.205 × X (14)

When the control current when the signal S becomes zero is calculated from the regression line, in the case of pure water, it is -0.0438A.
And the concentrations are 1000 mg / dl and 2000 mg
/ Dl aqueous glucose solution, 0.9
85A and 1.80A. When the correlation coefficient R with respect to the obtained regression line was obtained, it was 0.99 in the case of pure water.
It was 6. In addition, when the concentration is 1000 g / dl and 20
In the case of a 00 mg / dl glucose aqueous solution, they were 0.999 and 0.991, respectively. These serve as indices of how well each regression line fits. That is, this R
The closer the absolute value of is to 1, the higher the degree of adaptation of the obtained data to the regression line. When the correlation coefficient R is smaller than a predetermined numerical value, for example, when R <0.995, a high measurement accuracy can be obtained by invalidating the measurement result. When the difference from the set value of the control current value actually obtained from the regression line was determined, the difference was −0.0.
0638A, and -0.025A at a concentration of 1000 mg / dl and 2,000 m
g / dl was -0.2 A, and the one with a larger correlation coefficient R had a smaller error from the set value.

According to the first embodiment, since the entire time for sweeping the control current needs to be sufficiently longer than the time constant of the lock-in amplifier, the measurement must be performed to secure a high S / N ratio. It takes a long time. On the other hand, according to the present embodiment, it is sufficient to set the time from the start of supply of the control current to the determination of the signal S at the discrete measurement points to be 7 to 8 times larger than the time constant of the lock-in amplifier. Therefore, highly accurate measurement can be performed in a shorter time. As described above, according to the present embodiment, the rotation angle can be measured with high accuracy and in a short time for a test sample in a wide concentration range. Further, accuracy can be ensured by detecting a measurement result having a large error.

Embodiment 3 In this embodiment, a method for testing the urinary glucose concentration, that is, the urinary sugar level, to which the optical rotation angle measuring method of Embodiment 2 is applied will be described. In advance, the urine analyzer was used to determine that the concentration of albumin, a protein in urine, was 10 mg / dl or less and the glucose concentration was 45 mg / dl.
The optical rotation angles of urine 1 determined to be 0 mg / dl and urine 2 determined to have a glucose concentration of 655 mg / dl were measured using the polarimeter shown in FIG. It was measured. In addition, together with pure water and a concentration of 1000
The optical rotation angle was similarly measured for the aqueous glucose solution of mg / dl. These are used as criteria for determining the glucose concentration. The results obtained are shown in FIG.

[0055]

[Table 4]

For urine 1 and urine 2, the regression line with the control current as the reference variable X and the signal S as the dependent variable Y is expressed by the following equations (15) and (1) by the least squares method.
6).

Urine 1: Y = −0.0924 + 0.185 × X (15) Urine 2: Y = −0.0485 + 0.0803 × X (16)

From these regression lines, the control current when the signal S becomes zero is 0.499 A for urine 1 and 0.604 A for urine 2. If the influence of albumin in urine is neglected, the control current when the signal S becomes zero for each of urine 1, urine 2, pure water, and aqueous glucose solution is expressed by a linear function of the glucose concentration of these test samples. Can be. Therefore, the control current amount X when the signal S is set to be 0 in pure water.
₀ (GL ₀ ) and the signal S is 0 in the aqueous glucose solution.
Control current amount X ₀ (GL
₁₀₀₀ ), the urine glucose concentration Co
Can be calculated from the measured value X ₀ of the control current using the following equation (17).

Co = (X ₀ −X ₀ (GL ₀ )) × 1000 / (X ₀ (GL ₁₀₀₀ ) −X ₀ (GL ₀ )) = (X ₀ −0.02) × 1000 / 0.99 [ mg / dl] (17)

Thus, the glucose concentration of urine 1, that is, the urine sugar value was 484 mg / dl, and the urine sugar value of urine 2 was
It becomes 590 mg / dl.

Table 5 shows the measured data, the residual sum of squares S _E of the regression line, the normalized residual sum of squares D and the correlation coefficient R shown in equation (8). D is, as shown in equation (8), the residual sum of squares S _E and the reference variable X of the obtained regression line.
Variable Y obtained by substituting the control current data into
(Calculated value of signal S) divided by the sum of squares.

D = S _E / Σ (a + bX) ² (8) where the regression equation is Y = a + bX.

[0063]

[Table 5]

A comparison of the correlation coefficients shows that the regression equation for urine 1 has higher accuracy than that for urine 2. The smaller the residual sum of squares, the higher the accuracy of the regression equation. However, the residual sum of squares tends to decrease as the absolute value of the signal S decreases. Further, other factors such as the light transmittance of the test sample affect the absolute value. Therefore, it is not very advisable to directly compare the residual sum of squares between the test samples. Therefore, when the residual sum of squares is normalized and used as in the above D, comparison between test samples becomes easy. In fact,
As shown in Table 5, urine 2 has a smaller residual sum of squares than urine 1, but the regression equation of urine 1 has higher accuracy according to the correlation coefficient. This is because urine 2 has a lower transmittance than urine 1 and signal S
Because the absolute value of was small. However, regardless of the magnitude of the absolute value of the signal S, the normalized residual sum of squares D and correlation coefficient R function as an index of accuracy.

[0065]

According to the present invention, the signal S at a specific point is
In the conventional optical rotation angle measurement method of searching for the extinction point where the extinction point becomes zero while measuring the optical rotation angle measurement method, it is possible to prevent mixing of an error which is a concern, and a stable and accurate optical rotation angle measurement method in a short time and A urine test method can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a polarimeter used in one embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between a control signal injected into a Faraday cell and an intensity of a signal S output from a lock-in amplifier, obtained in the embodiment.

FIG. 3 is a block diagram showing a configuration of a polarimeter used in another embodiment of the present invention.

FIG. 4 is a characteristic diagram showing a relationship between a control signal injected into a solenoid coil and an intensity of a signal S output from a lock-in amplifier, obtained in the embodiment.

FIG. 5 is a characteristic diagram showing a relationship between a control signal injected into a solenoid coil and an intensity of a signal S output from a lock-in amplifier, obtained in still another embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of a conventional polarimeter.

[Explanation of symbols]

 1,21 Semiconductor laser module 3,23 Polarizer 4,24 Faraday cell 5,15,25 Sample cell 6,26 Analyzer 7,27 Optical sensor 8 Preamplifier 9,29 Faraday cell driver 10,30 Signal generator 11,28 Lock-in amplifier 12, 22 Computer 19, 29 Driver 20 Solenoid coil

Claims (14)

[Claims] 1. An optical rotation angle measurement for irradiating light to a test sample containing a natural optical rotation substance and measuring optical rotation caused by the natural optical rotation substance when the light passes through the test sample. A method of: (a) causing polarized light having a known vibration surface to enter the test sample while slightly vibrating the vibration surface with a modulation signal having an angular frequency ω; and (b) transmitting the test sample through the test sample. Detecting a component having a specific vibration plane in the polarized light by using an optical sensor; and (c) performing a phase sensitive detection using the modulated signal as a reference signal, thereby obtaining a component having an angular frequency of ω in the output signal of the optical sensor. (D) a relative angle between a vibration surface of light incident on the test sample and a vibration surface of light detected by the optical sensor, and the angular frequency obtained at the relative angle is a component of ω. Data including intensity Calculating an optical rotation angle of the test sample based on three or more sets of the optical rotation angle. 2. The optical rotation angle measuring method according to claim 1, wherein in step (a), the relative angle is changed by continuously rotating a vibration plane of the polarized light incident on the test sample. 3. The optical rotation angle measuring method according to claim 1, wherein, in step (a), the relative angle is changed by discretely changing a vibration plane of the polarized light incident on the test sample. 4. In step (d), a first-order regression equation is created based on the data, using the relative angle as a reference variable and the intensity of the component whose angular frequency is ω as a dependent variable. The optical rotation angle measurement method according to claim 1, wherein the optical rotation angle of the test sample is calculated based on a regression equation. 5. The optical rotation angle measuring method according to claim 1, wherein in step (a), the relative angle is changed by rotating a vibration plane of the polarized light incident on the test sample by an optical Faraday effect. 6. In the step (d), based on the data, a magnitude of a magnetic field for obtaining the relative angle or a current amount for generating the magnetic field is used as a reference variable, and the angular frequency is a component of ω. 6. The method for measuring an optical rotation angle according to claim 5, wherein a first-order regression equation is created with the intensity of as a dependent variable, and the optical rotation angle of the test sample is calculated based on the obtained regression equation. 7. A vibrating surface of the light passing through the test sample by applying light to the test sample containing the natural optical rotation substance and the magnetic optical rotation substance and applying a magnetic field to the test sample, thereby causing the light to vibrate. Rotated by the Faraday effect, the optical rotation generated due to the natural optical rotation material when the light passes through the test sample is measured based on the magnitude of the rotation of the light due to the application of the magnetic field. An optical rotation angle measuring method, wherein (a) a polarized light having a known vibration surface is incident on a test sample while the vibration surface is slightly vibrated by a modulation signal of an angular frequency ω; and (b) the test sample Detecting a component having a specific vibration plane in the polarized light transmitted through the optical sensor, and (c) performing phase-sensitive detection using the modulated signal as a reference signal, whereby the angular frequency of the output signal of the optical sensor is ω Success The method comprising the steps of: extracting,
(D ′) calculating an optical rotation angle of the test sample based on at least three sets of data including the magnitude of the magnetic field and the angular frequency obtained at the magnitude of the magnetic field including the intensity of the component of ω; Optical rotation angle measuring method comprising: 8. The method for measuring an optical rotation angle according to claim 7, wherein in the step (a), the vibrating surface of the light is continuously rotated by an optical Faraday effect. 9. The method according to claim 7, wherein in step (a), the vibrating surface of the light is discretely changed by an optical Faraday effect. 10. In step (d ′), based on the data, the magnitude of the magnetic field or the amount of current for generating the magnetic field is used as a reference variable, and the intensity of the component whose angular frequency is ω is set as a dependent variable. The optical rotation angle measuring method according to claim 7, wherein a first-order regression equation is created, and an optical rotation angle of the test sample is calculated based on the obtained regression equation. 11. The method according to claim 4, 6 or 10, wherein in step (d) or step (d ′), the regression equation is calculated using a least squares method. 12. The method according to claim 4, further comprising the step of determining that the measurement is valid when the reliability of the regression equation is higher than a predetermined value in step (d) or step (d ′). The method for measuring an optical rotation angle according to 6 or 10. 13. The index of evaluation of the reliability, obtained by substituting data corresponding residual sum of squares S _E shown in the following equation, the residual sum of squares S _E to the reference variable of the regression equation The optical rotation angle measurement method according to claim 12, wherein the angular frequency uses a value D divided by a sum of squares of intensity values of the component of ω, or a correlation coefficient R. (Equation 1) 14. A urine test method wherein the test sample is urine, and the concentration of the natural optical rotation substance in the urine is detected using the method for measuring the optical rotation angle according to claim 1 or 7.