JPH08136445A - Liquid absorbance measuring device - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] To provide a device for measuring absorbance of liquid, which can simultaneously measure the amount of scattered light, the amount of transmitted light, and the amount of absorbed light with one device. [Structure] A light-shielding container 2 for accommodating a transparent container 1 containing a liquid 10 to be tested, a light source 3 around the light-shielding container 2, and a first photoelectric device arranged in a direction in which light from the light source 3 travels straight. It has a converter 6 and a second photoelectric converter 8 arranged in a direction orthogonal to the direction in which the light from the light source 3 travels straight, and on the optical path from the light source 3 to the transparent container 1, from the transparent container 1 Apertures 11, 12, and 13 are provided on the respective walls of the light shielding container 2 on the optical path to the first photoelectric converter 6 and on the optical path from the transparent container 1 to the second photoelectric converter 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid absorbance measuring device which can be applied to, for example, analysis of the coloring degree of a liquid, the amount of a substance suspended in the liquid, and spectroscopic analysis and photometric titration. is there.

[0002]

2. Description of the Related Art The light transmittance of a liquid is calculated by putting the liquid in a prismatic cell, allowing parallel light to enter the surface of the cell, and measuring the amount of light emitted from the back surface. The transmitted light amount measured by this has both a loss due to light absorption due to coloring of the liquid and a loss due to irregular reflection due to insoluble matter floating in the liquid as parameters.

In order to analyze the characteristics of the liquid more accurately, it is preferable that the light loss due to absorption and the light loss due to scattering are measured as separate values. Therefore, in the past, liquid was placed in a prismatic cell, and parallel light was incident on the surface of the cell,
The amount of light emitted from the side surface of the cell was measured and the amount of scattered light was calculated. The absorbed light quantity is calculated from the scattered light quantity and the transmitted light quantity.

[0004]

Conventionally, there has not been a device capable of simultaneously measuring the scattered light amount, the transmitted light amount, and the absorbed light amount with one device and having a high sensitivity.

Moreover, the conventional measuring cell has a prismatic shape, and it is difficult to dissolve a powder sample or the like which is difficult to dissolve in the rectangular cell. Further, the solution contained in the prismatic cell has a drawback that other solution measurements such as viscosity measurement cannot be performed as they are.

The present invention has been made in order to solve the above-mentioned problems of the conventional technique, and it is possible to simultaneously measure the scattered light amount, the transmitted light amount, and the absorbed light amount with a single device with high sensitivity, and to measure the liquid to be tested. It is intended to provide an apparatus for measuring the absorbance of a liquid, which can be transferred to another solution measurement while being put in a cell.

[0007]

A liquid absorbance measuring apparatus of the present invention made to achieve the above object will be described with reference to FIGS. 1, 2 and 3 corresponding to the embodiments.

As shown in FIGS. 1 and 2, the liquid absorption measuring apparatus of the first embodiment to which the present invention is applied is a liquid 10 to be measured.
A light-shielding container 2 for accommodating a transparent container 1 in which is placed, a light source 3, a first photoelectric converter 6 arranged in a direction in which light from the light source 3 goes straight about the light-shielding container 2, and a light source 3 A second photoelectric converter 8 arranged in a direction orthogonal to the direction in which the light from the light travels straight, and on the optical path from the light source 3 to the transparent container 1, the transparent container 1 to the first photoelectric converter 6 Apertures 11 and 1 are provided on the respective walls of the light shielding container 2 on the optical path to the second photoelectric converter 8 and on the optical path to the second photoelectric converter 8 from the transparent container 1.
2 and 13 are provided.

Similarly, as shown in FIG. 3, the liquid absorption measuring apparatus of the second aspect to which the present invention is applied, means 16 for calculating the transmitted light quantity from the light quantity output from the first photoelectric converter 6, 18, means 17, 19 for calculating the diffused reflection light amount from the light amount output from the second photoelectric converter 8.
20, and means 21 for calculating the amount of light absorption from the amount of transmitted light and the amount of irregularly reflected light are added.

In the liquid absorbance measuring apparatus of the present invention, it is preferable that the transparent container 1 has a cylindrical shape, and the opening diameter d of the apertures 11, 12, and 13 is 1/6 or less of the cylindrical inner diameter D of the transparent container.

[0011]

The light from the light source 3 passes through the aperture 11 and the transparent container 1 and hits the test liquid 10. Test liquid 1
At 0, some component of the light is diffusely reflected by an undissolved substance or the like, some component is transmitted, and some component is absorbed by coloring of the solution. The transmitted light goes straight, passes through the transparent container 1, passes through the aperture 12, and is photoelectrically converted by the first photoelectric converter 6. Part of the components of the diffusely reflected light passes through the transparent container 1, passes through the aperture 13, and is photoelectrically converted by the second photoelectric converter 8.

With the output from the first photoelectric converter 6, the amount of transmitted light is calculated by the calculating means 16 and 18. With the output from the second photoelectric converter 8, the amount of diffused reflection light is calculated by the calculating means 17, 19, 20. The light absorption amount is calculated by the calculation means 21 from the transmitted light amount and the irregular reflection light amount.

When the transparent container 1 has a cylindrical shape, there are various advantages in handling, and when the opening diameter d of the apertures 11, 12, 13 is 1/6 or less of the cylindrical inner diameter D of the transparent container 1, the cylinder has a cylindrical shape. Inconvenience due to the fact that light passing therethrough is refracted only in the one-dimensional direction due to the curved surface of, for example, transmitted light does not focus well on the first photoelectric converter 6 or irregular reflection light on the second photoelectric converter 8. It is possible to prevent inconvenience caused by not focusing on.

[0014]

Embodiments of the liquid absorbance measuring apparatus of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing the construction of an embodiment of an absorbance measuring apparatus to which the present invention is applied, and FIG. 2 is a plan view of the same embodiment.

As shown in these figures, the apparatus is centered on a light-shielding container 2 for accommodating a transparent container 1, a halogen lamp 3 serving as a light source via a lens 4 on one side, and a lens 5 on the opposite side of 180 degrees from the halogen lamp 3. A photodiode 6, which is a photoelectric converter, and a photodiode 8, which is a photoelectric converter, are arranged in a 90-degree crossing direction through a lens 7. The transparent container 1 has a bottomed cylindrical shape with an inner diameter D, and the cylindrical portion is polished quartz glass. The light-shielding container 2 is a cylinder that is entirely painted black. The outer diameter of the transparent container 1 is very close to the inner diameter of the light shielding container 2. On the wall of the light-shielding container 2, an aperture 11 is provided on the optical path from the halogen lamp 3 to the transparent container 1 by the lens 4, an aperture 12 is provided on the optical path from the transparent container 1 to the photodiode 6 by the lens 5, and the transparent container 1 to the lens. An aperture 13 is provided on the optical path leading to the photodiode 8 by 7. The inner diameters d of the apertures 11, 12, and 13 are both 1/6 of the cylindrical inner diameter D of the transparent container 1. The apparatus of the above embodiment is equipped with the light amount calculation circuit shown in FIG.

The circuit is as follows: An analog-digital converter 18 is connected to the photodiode 6 via an analog amplifier 16. An analog-digital converter 19 is provided to the photodiode 8 via an analog amplifier 17.
Is connected. The digital output terminal of the analog-digital converter 18 is connected to the digital subtractor 21, and
The digital output terminal of the digital converter 19 is (2D / d) 2
It is connected to the digital subtractor 21 via the multiplication unit 20.

The absorbance measuring device shown in FIGS. 1, 2 and 3 operates as follows.

First, the liquid 10 to be inspected is put in the transparent container 1, and it is stored in a fixed position of the light shielding container 2. When the halogen lamp 3 is turned on, the light is collimated by the lens 4, passes through the aperture 11 and the wall of the transparent container 1, and enters the test liquid 10. In the test liquid 10, a part of the light is transmitted as parallel light. The transmitted light passes through the wall of the transparent container 1, passes through the aperture 12, is focused by the lens 5, and is detected by the photodiode 6. In addition, a part of the light incident on the test liquid 10 is irregularly reflected, and 360
The light is scattered in the three-dimensional direction, but a part of the light passes through the wall of the transparent container 1, passes through the aperture 13, is condensed by the lens 7, and is detected by the photodiode 8.

The transmitted light amount detected by the photodiode 6 is amplified by the analog amplifier 16, converted into a digital amount by the analog-digital converter 18, and input to the digital subtractor 21. On the other hand, it is output to the outside,
For example, it is supplied to a recorder or CRT display and can be used as data of the amount of transmitted light. The diffused reflection light amount detected by the photodiode 8 is amplified by the analog amplifier 16 and then converted into a digital amount by the analog-digital converter 19,
It is multiplied by (2D / d) 2 by the arithmetic unit 20 and input to the digital subtractor 21.

The reason why the diffused reflected light amount output from the photodiode 8 is multiplied by (2D / d) 2 is to match the transmitted light amount input to the digital subtractor 21 and the diffused reflected light amount per unit area. is there. That is, since the former is parallel light, the total amount of light that travels straight from the aperture 11 and passes through the liquid 10 passes through the aperture 12 and is detected by the photodiode 6. On the other hand, the latter diffusely reflects in the liquid 10 and is scattered by 360 degrees in the three-dimensional direction. Only the amount of light passing through the aperture 13 is detected by the photodiode 8. As described above, since the outer diameter of the transparent container 1 (approximately equal to the inner diameter D) is substantially equal to the inner diameter of the light shielding container 2, the opening area of the aperture 13 (opening diameter d) is π (d / 2) 2. On the other hand, the area of the distance from the center of the diffused reflection to the aperture 13 in the three-dimensional direction of 360 degrees is 4π (D / 2) 2. Therefore, the actual diffused reflection light amount is equal to 4 of the output light amount of the photodiode 8.
π (D / 2) 2 / π (d / 2) 2 = (2D / d) 2 times.

The amount of transmitted light and the amount of irregularly reflected light input to the digital subtractor 21 are subtracted to calculate the amount of absorbed light.

An experimental example in which the amount of transmitted light, the amount of diffusely reflected light, and the amount of absorbed light were measured using the absorbance measuring apparatus of this example will be described below.

A hydroxylpropylmethyl cellulose aqueous solution (3 cP) having a concentration of 2% was placed in a cylindrical transparent container 1 having various inner diameters and a rectangular transparent container having an optical path length corresponding to the inner diameter of the cylinder, and the wavelength of 280 nm from the light source 3 was used. UV light was irradiated with various apertures, and the absorbance detected by the photodiode 6 was measured. The results are shown in Table 1. In Experimental Example 1 to Experimental Example 3 and Experimental Example 6 to Experimental Example 8, the ratio d / D between the opening diameter d of the aperture 11 and the aperture 13 and the inner diameter D of the cylindrical transparent container opening 1 is 1/6 or less, and the present invention is performed. In Comparative Example 4 / Comparative Example 5 and Comparative Example 9 / Comparative Example 10, the ratio d / D of the opening diameter d of the aperture 11 and the aperture 13 to the inner diameter D of the cylindrical transparent container opening 1 is 1.
/ 6 or more, which is an example to which the present invention is not applied.

[0025]

[Table 1]

As can be seen from Table 1, Experimental Examples 1 to 3
In Experimental Example 6 to Experimental Example 8, the absorbance detected by the photodiode 6 is substantially the same regardless of whether the transparent container is cylindrical or rectangular, which is disadvantageous because the transparent container has a cylindrical shape. However, in Comparative Example 4 / Comparative Example 5 and Comparative Example 9 / Comparative Example 10, the absorbance detected by the photodiode 6 is different between the case where the transparent container is a cylinder and the case where the transparent container is a square type, and the transparent container is a cylinder. It can be seen that the measured value is inaccurate due to the influence of the curve of the cylindrical wall surface because of the shape. Therefore, the opening diameter d of the apertures 11 and 13 needs to be 1/6 or less of the inner diameter D of the transparent container opening 1.

[0027]

As described above in detail, the liquid absorbance measuring apparatus to which the present invention is applied can simultaneously measure the scattered light amount, the transmitted light amount, and the absorbed light amount with high sensitivity with one device.
Moreover, since the liquid cell of the transparent container for containing the test liquid can be a cylindrical one, it is convenient that the test liquid can be transferred to another solution measurement as it is.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of an embodiment of an absorbance measuring apparatus to which the present invention is applied.

FIG. 2 is a plan view of the apparatus of the embodiment.

FIG. 3 is a light amount calculation circuit added to the apparatus of the above embodiment.

[Explanation of symbols]

1 is a transparent container, 2 is a light-shielding container, 3 is a halogen lamp, 4
・ 5, 7 is a lens, 6.8 is a photodiode, 10 is a liquid to be tested, 11 ・ 12 ・ 13 is an aperture, 16 ・ 1
Reference numeral 7 is an analog amplifier, 18 and 19 are analog-digital converters, 20 is a (2D / d) double calculator, and 21 is a digital subtractor.

Claims (4)

[Claims] 1. A light-shielding container for accommodating a transparent container containing a liquid to be tested, a light source around the light-shielding container, and a first photoelectric converter arranged in a direction in which light from the light source travels straight. A second photoelectric converter arranged in a direction orthogonal to the direction in which the light from the light source travels straight, on the optical path from the light source to the transparent container, from the transparent container to the first photoelectric converter. An apparatus for measuring absorbance of a liquid, characterized in that an aperture is provided on each wall of the light-shielding container on the light path to reach the light path and on the light path from the transparent container to the second photoelectric converter. 2. A means for calculating the amount of transmitted light from the amount of light output from the first photoelectric converter, a means for calculating the amount of diffuse reflection light from the amount of light output from the second photoelectric converter, and the transmission. A means for calculating a light absorption amount from the light amount and the diffused reflection light amount is added.
An apparatus for measuring absorbance of a liquid according to item 1. 3. The liquid absorbance measuring device according to claim 1, wherein the transparent container has a cylindrical shape, and the opening diameter of the aperture is 1/6 or less of the cylindrical inner diameter of the transparent container. 4. The black inner surface of at least the transparent container facing the transparent container is black.
An apparatus for measuring absorbance of a liquid according to item 1.