JPH0534277A - Ultraviolet absorption detector - Google Patents

Abstract

PURPOSE:To remove the shift in wavelength between a sample light and a comparison light thereby to stabilize the output, by performing zero calibration and wavelength calibration at both sides of the sample light and comparison light. CONSTITUTION:The irradiation light from a light source 1 is reflected at 2 and condensed at an slit 3 for incident light. The light passing through the slit 3 is reflected at 4 and turned to parallel lights. A diffration grating 5 splits the parallel light into lights of various wavelengths which in turn enter a concave mirror 6. The light of the parallel lights reflected at the center of the mirror 6 is, through a projecting slit 8 arranged in the vicinity of the focal point of the mirror 6 and a flow cell 9, detected by a sample light sensor 10. The light reflected at the end of the mirror 6 is reflected at 7, and then detected by a comparison light sensor 12 through a slit 11 for emitted light for comparison in the vicinity of the focal point of the mirror 7. The absorbance of the fluid running in the cell 9 is operated and detected based on the detecting signals of the sensors 10, 12. At this time, the grating 5 and the half mirror 7 are adjusted minute angles by motors 3, 4 respectively, thereby to achieve zero calibration and wavelength calibration at both sides of the sample light and the comparison light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultraviolet absorption detector, and more specifically, it is used as a detector for a high performance liquid chromatograph or the like, and a sample flowing in a flow cell is irradiated with ultraviolet rays to determine the decrease amount of the ultraviolet rays. The present invention relates to an ultraviolet absorption detector that detects a component to be measured in the sample.

[0002]

2. Description of the Related Art FIG. 2 is a diagram for explaining the general structure of an ultraviolet absorption detector. Is a harf mirror, 8 and 11 are exit slits, 9 is a flow cell, 10 is a sample photosensor, and 12 is a comparative photosensor. In the conventional ultraviolet absorption detector having such a configuration, the light emitted from the light source 1 is reflected by the concave mirror 2 and focused on the entrance slit 3. Further, the light that has passed through the entrance slit 3 is reflected by the concave mirror 4 and becomes parallel light, which is split into lights of various wavelengths by the diffraction grating 5.

Of the parallel light that is incident on the concave mirror 6 in this way, light of a specific wavelength passes through the exit slit 8 and the flow cell 9 arranged near the focal point of the concave mirror 6, and passes through the sample optical sensor. -10 is detected. Also, a part of the parallel light incident on the concave mirror 6 is reflected by the half mirror 7 and then passes through the exit slit 11, and then the comparative optical sensor-1.
Detected in 2.

On the other hand, a sample is flown into the flow cell 9, and the light intensity of the sample changes according to the component concentration of the sample. Therefore, A, I, and I _o are the absorbance,
When the sample light output and the comparison light output are used, the change in the absorbance A is output according to the Lambert-Beer law shown in the following equation (1). A = lLog (I _o / I) …………………… (1)

Incidentally, when the sample light output I changes by 0.1%, the absorbance A becomes -4.4 as shown in the following equation (2).
It changes by × 10 ^-4 . _{ΔA = Log (I o / I} ) -Log {I o /(0.999I)} = Log (0.999) = -4.4 × 10 -4 .............................. (2)

[0006]

However, in the above-mentioned conventional example, in the zero point calibration and the wavelength calibration of the optical system, the angle of the diffraction grating 5 is slightly moved to monitor only the output on the sample light side. Was there. Therefore, there is a drawback in that the observed wavelength is different between the sample light side and the comparison light side, which adversely affects the output of the detector. The present invention has been made in view of the drawbacks of the conventional example, and an object thereof is to provide an ultraviolet absorption detector in which the output is stable without a wavelength shift between the sample light side and the comparison light side. It is in.

[0007]

SUMMARY OF THE INVENTION According to the present invention, light emitted from a light source is reflected by a first concave mirror and condensed on an entrance slit, and light passing through the entrance slit passes through a second concave mirror to form parallel light. After being split into light of various wavelengths by the diffraction grating, the light of a specific wavelength among the light that is incident on the third concave mirror and becomes parallel is output to the exit slit arranged near the focal point of the third concave mirror. In the ultraviolet absorption detector that detects the component to be measured in the sample that flows through the flow cell through the flow cell and is detected by the optical sensor, place a half mirror between the third concave mirror and the output slit. The above problem is solved by providing a motor for rotating the half mirror while being installed.

[0008]

The present invention operates as follows. That is, in zero calibration and wavelength calibration of the optical system, first, the diffraction grating is moved by a small angle, and zero calibration and wavelength calibration on the sample light side at that time are performed. Next, the beam splitter is moved by a slight angle, and the output value on the comparison light side at that time is monitored to perform zero calibration or wavelength calibration on the comparison light side. By thus performing the zero calibration and the wavelength calibration on both the sample light side and the comparison light side, the wavelength shift between the two is eliminated.

[0009]

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a configuration explanatory view for explaining an embodiment of the present invention. In the figure, the same symbols as those in FIG. 2 are used with the same meanings, and duplicate explanations are omitted here. Further, 13 'is a first motor for rotating the diffraction grating 5, and 14 is a second motor for rotating the beam splitter 7.

In the embodiment of the present invention having such a structure, the light emitted from the light source 1 is reflected by the concave mirror 2 and focused on the entrance slit 3. In addition, the entrance slit 3
The light that has passed through becomes a parallel light through the concave mirror 4 and is split into lights of various wavelengths by the diffraction grating 5. The light of a specific wavelength of the parallel light thus split and incident on the concave mirror 6 is condensed at its focal point.

Here, the concave mirror 6 has two curved surfaces of a first spherical surface 6a (a central portion of the concave mirror 6) and a second spherical surface 6b (an end portion of the concave mirror 6) as shown in FIG. The focus of the first spherical surface 6a and the focus of the second spherical surface 6b are different. Therefore, the light reflected by the first spherical surface 6a passes through the exit slit 8 disposed near the focal point of the first spherical surface 6a, becomes light of a limited band width, passes through the flow cell 9, and passes through the sample optical sensor. -10 is detected.

The light reflected by the second spherical surface 6b is
Exit slit 11 for comparison light, which is arranged near the focal point of
The light with a limited bandwidth passes through the frothel 9
And is detected by the comparative optical sensor-12. in this way
Then, the detection signal detected by the sample optical sensor-10
(I) and the detection signal (I
_o), The calculation as shown in the equation (1) is performed.
And the UV absorbance of the fluid flowing in the flow cell 9 is detected.
It is supposed to be done.

That is, in zero calibration and wavelength calibration of the optical system, first, the diffraction grating 5 is moved by a minute angle, and zero calibration and wavelength calibration on the sample light side at that time are performed. Next, bee
The splitter is moved by a small angle and the output value on the comparison light side at that time is monitored to perform zero calibration or wavelength calibration on the comparison light side. In this way, by performing the zero calibration and the wavelength calibration on both the sample light side and the comparison light side, the wavelength shift between the two is eliminated.

The present invention is not limited to the embodiment shown in FIG. 1, and various modifications are possible. For example, the following may be adopted. Used not only for UV absorption detectors, but also for infrared and other optical system detectors. The principal axis of the concave mirror is not parallel to the vertical direction, but the focal length is shifted.

[0015]

According to the present invention as described in detail above, an ultraviolet absorption detector having a stable output with no wavelength shift between the sample light side and the comparison light side can be realized.

[Brief description of drawings]

FIG. 1 is a structural explanatory view of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a configuration of a conventional example. 1 Light Source 2, 4, 6 Concave Mirror 3 Entrance Slit 5 Diffraction Grating 7 Haar Miller 8, 11 Exit Slit 9 Flow Cell 10 Sample Optical Sensor-12 Comparative Optical Sensor-13, 14 Motor

Claims (1)

Claim: What is claimed is: 1. Light emitted from a light source is reflected by a first concave mirror and condensed on an incident slit, and light passing through the incident slit passes through a second concave mirror to become parallel light and diffracted. The light of a specific wavelength, of the light that has been split into light of various wavelengths by the grating and then entered the third concave mirror and becomes parallel, is output from the output slit and the flow slit arranged near the focal point of the third concave mirror. -In the ultraviolet absorption detector which detects the component to be measured in the sample flowing through the flow cell by passing through the cell and detecting with an optical sensor, a half mirror is provided between the third concave mirror and the exit slit. An ultraviolet absorption detector characterized by being provided with a motor for rotating the half mirror.