JPH0434341A - Ultraviolet absorption detector - Google Patents

Abstract

PURPOSE:To make the title detector resistant to a change in environment and to facilitate optical adjustment by forming first and second spherical surfaces on a third concave mirror and by specifying the relationship in disposition of a slit for sample light with a slit for comparison light and of a sensor for sample light with a sensor for comparison light. CONSTITUTION:A light reflected by a first spherical surface 6a passes through an emission slit 8 disposed in the vicinity of the focus of the spherical surface and is detected by a sample light sensor 10 through a flow cell 9. A light reflected by a second spherical surface 6b passes through an emission slit 11 for comparison light disposed in the vicinity of the focus of this sperical surface and is detected by a comparison light sensor 12 through the flow cell 9. Computation is executed on the basis of a signal of detection by the sample light sensor 10 and a signal of detection by the comparison light sensor 12 in this way, and the absorbance of ultraviolet rays of a fluid flowing through the flow cell 9 is detected.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention is used as a detector in a high performance liquid chromatograph, etc., and a sample flowing through a flow cell is irradiated with ultraviolet rays, and from the amount of decrease in ultraviolet rays, the amount of exposure in the sample is determined. This invention relates to an ultraviolet absorption detector that detects components to be measured.

<Prior art> Fig. 5 is a general configuration explanatory diagram of an ultraviolet absorption detector, in which 1 is a light source, 2, 4.6 are concave mirrors, 3 is an entrance slit, 5 is a diffraction grating, are half mirrors 18 and 11 are output slits, 9 is a flow cell, 10 is a sample light sensor, and 12 is a comparison light sensor. In a conventional ultraviolet absorption detector having such a configuration, light emitted from a light source 1 is reflected by a concave mirror 2 and focused on an entrance slit 3. Further, the light passing through the entrance slit 3 is reflected by the concave mirror 4 and becomes parallel light, which is separated by the diffraction grating 5 into light of various wavelengths. Of the parallel light incident on the concave mirror 6 separated in this way, light of a specific wavelength is
The light passes through an exit slit 8 and a flow cell 9 arranged near the focal point of the light beam, and is detected by a sample optical sensor 10. In addition, a part of the parallel light incident on the concave mirror 6 is transmitted to the half mirror.
After being reflected at 7, the light passes through an exit slit 11 and is detected by a comparison optical sensor 12.

On the other hand, a sample is flowing into the flow cell 9, and the light intensity of the sample changes depending on the component concentration of the sample. Therefore, when A, I, and Io are the absorbance, the sample light output, and the comparative light output, respectively, the change in the absorbance A is output according to the Lambert-Baer law shown in equation (1) below.

A=i'os (Io/I)・-”・(1) By the way,
When the sample light output ■ changes by 0.1%, the absorbance A changes by −4.4×10 4 as shown in equation (2) below.

ΔA=i'os (Io/I) los (Io/
(0,999I)) =10s (0,999) =-4,4X10'・・・・・・・・・・・・・・・(
2) <Problems to be solved by the invention> However, in the above-mentioned conventional example, the housing of the optical system may be distorted, the orientation of the half mirror may change, or the temperature changes of each sensor may differ due to changes in the environmental temperature. As a result, the outputs of the sample light sensor and comparison light sensor may change.

It also changes due to external forces such as vibrations.

Therefore, there is a drawback that the absorbance output changes even though the concentration of the sample remains unchanged.

Further, when considering the causes of such a change in absorbance output, it was as follows. That is, (1) the sample light and the comparison light are separated, and the sensor is located at a separate position. For this reason, when the ambient temperature or strain changes, the effects of the sensor output on the sample and comparison light are not the same, ultimately causing noise, fluctuation, or drift in the sensor output.

■It is difficult to match the wavelengths of the sample and comparison light, although it is not possible to compensate for spectral changes caused by the light source unless the sample and comparison light have the same wavelength.

The present invention was made in view of this situation, and its object is to provide an ultraviolet absorption detector that is resistant to environmental changes and whose optical adjustment is easy.

<Means for Solving the Problems> In the present invention, light emitted from a light source is reflected by a first concave mirror and focused on an entrance slit, and the light passing through the entrance slit passes through a second concave mirror and becomes parallel. After becoming light and being split into light of various wavelengths by a diffraction grating, the light of a specific wavelength among the light that enters the third concave mirror and becomes parallel is emitted by an output device disposed near the focal point of the third concave mirror. In an ultraviolet absorption detector that detects a component to be measured in a sample flowing inside the flow cell by detecting it with an optical sensor through a slit and a flow cell, first and second spherical surfaces are formed on the third concave mirror,
The main axes of the curved surface of the first spherical surface are vertically parallel, the sample light slit and the comparison slit are arranged vertically close to each other, and the sample light optical sensor and the comparison optical sensor are vertically close to each other. This is due to the fact that it was arranged.

<Example> Hereinafter, the present invention will be described in detail using the drawings. 1st
The figure is an explanatory diagram of the main part configuration of the embodiment of the present invention, and in the figure, the fifth
The same symbols as in the figures are used with the same meaning, and redundant explanation will be omitted here. 2 is a side view of the portion from the concave mirror 6 to the optical sensor 10.12 in FIG. 1. Furthermore, FIG. 3 is a three-dimensional perspective view of the concave mirror 6, and FIG. 4 is a three-dimensional perspective view of the exit slit. Further, in FIG. 3, 6a is the first spherical surface of the concave mirror 6, and 6b is the second spherical surface of the concave mirror 6. Note that in FIGS. 2 to 4, the same symbols as in FIG. 5 are used with the same meaning, and repeated explanation here will be omitted. Further, the focal lengths of the first spherical surfaces 6a and 6b can be set freely, but in the embodiment of the present invention, only the heights differ, and the principal axes of each curved surface are vertically parallel, compared to the sample optical sensor 10. The optical sensor 11 is arranged at the nearest point 1.

In the embodiment of the present invention having such a configuration, light emitted from the light source 1 is reflected by the concave mirror 2 and focused on the entrance slit 3. Further, the light passing through the entrance slit 3 passes through the concave mirror 4 and becomes parallel light, and is separated by the diffraction grating 5 into lights of various wavelengths. Among the parallel lights that have been separated in this way and are incident on the concave mirror 6, light of a specific wavelength is condensed at its focal point.

Here, the concave mirror 6 has two curved surfaces, a first spherical surface 6a and a second spherical surface 6b, as shown in FIG.
The focal point of the second spherical surface 6b is aligned with the focal point of the second spherical surface 6b. Therefore, the light reflected by the first spherical surface 6a passes through the output slit 8 disposed near the focal point, becomes light with a limited bandwidth, passes through the flow cell 9, and is detected by the sample light sensor 10. Detected. Further, the light reflected by the second spherical surface 6b passes through the comparison light output slit 11 disposed near the focal point, becomes light with a limited bandwidth, passes through the flow cell 9, and passes through the comparison light sensor 12. Detected in In this way, the calculation shown in equation (1) above is performed based on the detection signal (I) detected by the sample optical sensor 10 and the detection signal (Io) detected by the comparison optical sensor 12. , the ultraviolet absorbance of the fluid flowing inside the flow cell 9 is detected.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and can be modified in various ways, such as the following (1) and (2). ■Used not only for ultraviolet absorption detectors but also for infrared and other optical system detectors. ■The main axis of the concave mirror is not parallel to the vertical direction, but the focal length is shifted.

<Effects of the Invention> As explained in detail above, the present invention is such that the light emitted from the light source is reflected by the first concave mirror and focused on the entrance slit, and the light that has passed through the entrance slit passes through the second concave mirror. After the light becomes parallel light and is split into light of various wavelengths by a diffraction grating, the light of a specific wavelength among the light that enters the third concave mirror and becomes parallel is arranged near the focal point of the third concave mirror. In an ultraviolet absorption detector that detects a component to be measured in a sample flowing in the flow cell by detecting it with an optical sensor through an exit slit and a flow cell, the third concave mirror is formed with first and second spherical surfaces, The main axes of the curved surface of the first spherical surface are vertically parallel, the sample light slit and the comparison slit are arranged vertically close to each other, and the sample light optical sensor and the comparison optical sensor are vertically close to each other. It was configured to be installed.

Therefore, the following effects (1) to (2) can be obtained.

■The sample light sensor and comparison light sensor can be placed very close to each other and the temperature conditions can be made equal, making it possible to minimize changes in sensor sensitivity due to temperature.

■Since the sample light sensor and comparison light sensor can be placed extremely close together and the temperature conditions can be made equal, changes in light caused by mechanical distortion of the optical system due to temperature changes can be canceled out.

■The light separated by the diffraction grating is focused on two focal points, and slits and optical sensors can be placed at those positions.

Therefore, the optical system is bright with high light utilization efficiency, and high-sensitivity measurements are also possible.

■The principal axes of the first spherical surface and the principal axes of the second spherical surface in the concave mirror 6 are vertically parallel, and the comparison light output slit and the sample light output slit can be simply arranged above and below to allow light of the same wavelength to enter. I will do it. Because of this, when optical adjustment of the sample light is performed, optical adjustment of the comparison light is also performed at the same time, making the optical adjustment easier. Furthermore, since the sample light and comparison light automatically become the same light, even if the spectral intensity of the light source changes, they cancel each other out.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the main part configuration of the embodiment of the present invention, and Figure 2 is the first
A diagram of the part from the concave mirror to the optical sensor seen from the turret,
FIG. 3 is a three-dimensional perspective view of a concave mirror, FIG. 4 is a three-dimensional perspective view of an exit slit, FIG. 5 is an explanatory diagram of the configuration of a conventional example, and FIG. 6 is a detailed explanatory diagram of the flow cell portion of FIG. 1... Light source, 2.4.6... Concave mirror, 6a, 6b.
... Spherical surface, 3 ... Input slit, 5 ... Diffraction grating,
7... Half mirror 58, 11... Output slit, 9... Flow cell, 10... Sample optical sensor 1
2...Comparative optical sensor Hata Ku・8 Output slit Figure 10

Claims (1)

[Claims] The light emitted from the light source is reflected by the first concave mirror and focused on the entrance slit, and the light that has passed through the entrance slit is focused on the second concave mirror.
After passing through the concave mirror, it becomes parallel light and is separated into light of various wavelengths by a diffraction grating, and then enters a third concave mirror and among the parallel light, a specific wavelength of light is transmitted near the focal point of the third concave mirror. through the exit slit and flow cell arranged in the
In an ultraviolet absorption detector that detects a component to be measured in a sample flowing through the flow cell by an optical sensor, first and second spherical surfaces are formed on the third concave mirror, and the principal axis of each curved surface of these spherical surfaces is The ultraviolet rays are vertically parallel, the sample light slit and the comparison slit are arranged close to each other vertically, and the sample light sensor and the comparison light sensor are arranged close to each other vertically. Absorption detector.