JP2874288B2 - UV absorption detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention is used as a detector for a high-performance liquid chromatograph or the like, and irradiates a sample flowing in a flow cell with ultraviolet rays. The present invention relates to an ultraviolet absorption detector that detects a measurement component.

<Prior Art> FIG. 5 is a diagram illustrating a general configuration of an ultraviolet absorption detector. In FIG. 5, 1 is a light source, 2, 4, and 6 are concave mirrors, 3 is an entrance slit, 5 is a diffraction grating, 7 is a half mirror, 8 and 11 are exit slits, 9 is a flow cell, 10 is a sample optical sensor, 12
Is a comparative light sensor. In the conventional ultraviolet absorption detector having such a configuration, light emitted from the light source 1 is reflected by the concave mirror 2 and condensed on the entrance slit 3.
The light passing through the entrance slit 3 is reflected by the concave mirror 4 and becomes parallel light, which is split by the diffraction grating 5 into light of various wavelengths. The light of a specific wavelength out of the parallel light incident on the concave mirror 6 thus split passes through the exit slit 8 and the flow cell 9 disposed near the focal point of the concave mirror 6, and is detected by the sample optical sensor 10. . A part of the parallel light incident on the concave mirror 6 is reflected by the half mirror 7, passes through the exit slit 11, and is detected by the comparative light sensor 12.

On the other hand, a sample is flowing through the flow cell 9, and the light intensity of the sample changes according to the component concentration of the sample.
For this reason, A, I, _Io are defined as absorbance, sample light output,
When the comparative light output is used, the Lambertian equation shown in the following equation (1)
The change in the absorbance A is output according to Beer's law.

A = l _og (I _o / I) (1) Incidentally, when the sample light output I changes by 0.1%, the absorbance A changes by −4.4 × 10 ⁻⁴ as shown in the following equation (2). .

ΔA = l _og (I _o / I) −l _og {I _o /(0.999I)}=l _og (0.999) = − 4.4 × 10 ⁻⁴ (2) <Problems to be solved by the invention> However, in the above conventional example, the housing of the optical system is distorted due to a change in environmental temperature, the direction of the half mirror is changed, or the temperature change of each sensor is different, resulting in the output of the sample light sensor and the comparison light sensor. May change. It also changes due to external force such as vibration.

For this reason, there is a disadvantage that the absorbance output changes despite the fact that the concentration of the sample remains unchanged.

Further, the cause of such a change in the absorbance output was considered as follows. That is, the sample light and the comparison light are separated, and the sensor is at a remote position. For this reason, when the ambient temperature and the distortion change, the influence of the sensor output of the sample and the comparative light does not become the same, and ultimately causes noise, fluctuation or drift of the sensor output.

If the sample and the comparison light do not have the same wavelength, it is difficult to make the wavelengths of the sample and the comparison light uniform even though the spectral change of the light source or the like cannot be compensated.

The present invention has been made in view of such a situation, and an object of the present invention is to provide an ultraviolet absorption detector that is resistant to environmental changes and easy to adjust optically.

<Means for Solving the Problems> A first concave mirror that reflects light emitted from a light source, an incident slit that collects light reflected by the first concave mirror, and a light that reflects light passing through the incident slit The second to be parallel light
A concave mirror, a diffraction grating for receiving light reflected by the second concave mirror, a third concave mirror for reflecting light of a specific wavelength out of the light split by the diffraction grating, and a light source disposed near a focal point of the third concave mirror. A second slit and a flow cell, and an ultraviolet absorption detector for detecting a measurement component in a sample flowing through the flow cell, wherein the optical axis of reflected light is parallel to the third concave mirror and the focal length is substantially the same. Forming two spherical surfaces, disposing a sample light exit slit near the focal point of light reflected by one spherical surface, and sequentially arranging a flow cell and a sample light sensor after the sample light exit slit, and forming the other spherical surface. The comparative light exit slit and the comparative light sensor are sequentially arranged near the focal point of the light reflected by the light source.

<Example> Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory view of a main part configuration of an embodiment of the present invention. In FIG. 1, the same symbols as those in FIG. 5 are used with the same meanings, and redundant description is omitted here. FIG. 2 is a side view of a portion from the concave mirror 6 to the optical sensors 10 and 12 in FIG.
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. In FIG. 3, reference numeral 6a denotes a first spherical surface of the concave mirror 6, and 6b denotes a second spherical surface of the concave mirror 6. 2 to 4, the same symbols as those in FIG. 5 are used with the same meanings, and duplicate explanations are omitted here. Although the focal lengths of the first spherical surface 6a and the second spherical surface 6b can be freely set, in the embodiment of the present invention, only the heights are different. The reference light sensor 10 and the comparison light sensor 12 are arranged at close positions.

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 condensed on the entrance slit 3. The light that has passed through the entrance slit 3 passes through the concave mirror 4 and becomes parallel light, which is split by the diffraction grating 5 into light of various wavelengths. The light of a specific wavelength among the parallel lights incident on the concave mirror 6 thus split is focused on the focal point.

Here, the concave mirror 6 has two curved surfaces of a first spherical surface 6a and a second spherical surface 6b as shown in FIG. 3, and the focal point of the first spherical surface 6a and the focal point of the second spherical surface 6b are different. Therefore, the first
The light reflected by the spherical surface 6a passes through the exit slit 8 disposed near the focal point, becomes light having a limited bandwidth, passes through the flow cell 9, and is detected by the sample light sensor 10. The light reflected by the second spherical surface 6b passes through a comparative light exit slit 11 disposed near the focal point, and becomes light of a limited bandwidth to form a comparative light sensor.
Detected at 12. In this way, the sample light sensor
Based on the detection signal (I) detected by 10 and the detection signal (I _o ) detected by the comparison optical sensor 12, the operation shown in the above-mentioned equation (1) is performed, and the fluid flowing in the flow cell 9 is obtained. Is detected.

It should be noted that the present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the following may be adopted. Used not only for ultraviolet absorption detectors but also for infrared and other optical detectors. The main axis of the concave mirror is not parallel to the vertical direction, and the focal length is shifted.

<Effects of the Invention> As described in detail above, the present invention provides a first concave mirror that reflects light emitted from a light source, an entrance slit that collects light reflected by the first concave mirror, A second concave mirror that reflects the transmitted light into parallel light, a diffraction grating that receives the light reflected by the second concave mirror, and a third grating that reflects light of a specific wavelength among the light separated by the diffraction grating. A concave mirror, a second slit and a flow cell disposed near the focal point of the third concave mirror, and an ultraviolet absorption detector for detecting a measurement component in a sample flowing in the flow cell; a light reflected by the third concave mirror; Two spherical surfaces whose axes are parallel and whose focal lengths are almost the same are formed. A sample light exit slit is arranged near the focal point of the light reflected by one of the spherical surfaces. Sequentially arranged sensor cell and sample light, were sequentially disposed the other focus exit slit and comparative light sensor compared the optical near the light reflected by the spherical surface.

 Therefore, the following effects are obtained.

Since the sample optical sensor and the comparative optical sensor can be arranged at extremely close positions and the temperature conditions can be made equal, a change in sensor sensitivity due to temperature can be reduced.

Since the sample optical sensor and the comparative optical sensor can be disposed very close to each other 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 offset.

The light split by the diffraction grating is collected at two focal points, and a slit or an optical sensor can be provided at that position. Therefore, the optical system has a high light use efficiency and is bright, and high-sensitivity measurement is possible.

The main axis of the first spherical surface and the main axis of the second spherical surface of the concave mirror 6 are vertically parallel to each other, and light of the same wavelength is incident simply by disposing the emission slit for comparison light and the emission slit for sample light vertically. Will be. Therefore, if the optical adjustment of the sample light is performed, the optical adjustment of the comparison light is also performed at the same time, and the optical adjustment is facilitated. Further, since the light of the sample light and the light of the comparison light automatically become the same light, even if the spectrum intensity of the light source or the like changes, the light is canceled.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a main part of an embodiment of the present invention, and FIG.
View from the side of the part from the concave mirror of the figure to the optical sensor,
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 a configuration explanatory view of a conventional example, and FIG. 6 is a detailed explanatory view of a flow cell part of FIG. 1 ... Light source, 2,4,6 ... Concave mirror, 6a, 6b ... Spherical, 3 ...
Entrance slit, 5 ... diffraction grating, 7 ... half mirror,
8,11 ... Emission slit, 9 ... Flow cell, 10 ... Sample light sensor, 12 ... Comparative light sensor,

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01N 21/00-21/01 G01N 21/17-21/61

Claims (1)

(57) [Claims] 1. A first concave mirror for reflecting light emitted from a light source, an entrance slit for condensing light reflected by the first concave mirror, and light passing through the entrance slit is reflected to be parallel light. A second concave mirror, a diffraction grating for receiving light reflected by the second concave mirror, a third concave mirror for reflecting light of a specific wavelength out of the light split by the diffraction grating, and a light source near the focal point of the third concave mirror. A second slit and a flow cell disposed therein, and an ultraviolet absorption detector for detecting a measurement component in a sample flowing in the flow cell, wherein the optical axis of the reflected light is parallel to the third concave mirror and the focal length is substantially the same. Are formed close to each other, a sample light exit slit is disposed near the focal point of the light reflected by one of the spherical surfaces, and a flow cell and a sample light sensor are arranged in the subsequent stage of the sample light exit slit. An ultraviolet absorption detector, comprising: an output slit for comparative light and a sensor for comparative light sequentially arranged near the focal point of light reflected by the other spherical surface.