JP2006300671A - Spectroscopic detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spectroscopic detector having both detection of high sensitivity and a wide wavelength selection range. <P>SOLUTION: A plane mirror 9 is movable, and light dispersed spectrally from mirror 5 reaches a sample cell 11 when the mirror 9 is located in a position indicated by a doted line, and an absorbance by a sample is measured over the wide wavelength range. Light from a laser 15 is reflected by the plane mirror 9 therein, and does not reach the sample. When the plane mirror 9 located in a position indicated by a solid line, the light from the laser 15 is reflected by the plane mirror 9 therein to reach the sample cell 11, and the absorbance by a sample is measured. The detection of high sensitivity is possible since the light emitted from the laser 15 is converged into a small point with a small opening angle to get incident into the sample cell. The light from mirror 5 is reflected by the plane mirror 9 therein not to reach the sample. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a spectroscopic detection apparatus that irradiates a sample with light subjected to spectroscopy and measures light that is transmitted through the sample, reflected light, or fluorescence generated from the sample.

  In an absorbance detector that measures light transmitted through the sample to be measured and a fluorescence detector that measures fluorescence generated from the sample to be measured, the measurement is performed by irradiating the sample with a specific wavelength. As a means for irradiating light of a specific wavelength, a discharge lamp such as a deuterium lamp or a xenon lamp is used as a light source, and a wavelength selection means such as a spectral filter such as a grating or a filter such as an interference filter is combined. This is because it has an advantage that the optimum wavelength of the irradiation light can be selected in accordance with the absorption spectrum of the sample to be analyzed or the sample excitation wavelength.

  FIG. 3 shows a schematic configuration diagram of a conventional absorbance detector. Light emitted from a light source 41 such as a deuterium lamp is condensed on a slit 47 by a mirror 43. The light that has passed through the slit 47 is applied to the grating 49 by the mirror 44, and the light dispersed by the grating 49 is condensed on the sample cell 51 by the mirror 45. By rotating the grating 49, the sample cell 51 can be irradiated with light of a specific wavelength. A sample is sealed or passed through the sample cell 51, and the absorbance of the sample can be measured by measuring the intensity of light transmitted through the sample with a photodetector 53 such as a photomultiplier tube.

In the detection of absorbance or fluorescence, the detection sensitivity is improved as the intensity of light applied to the sample is increased. Moreover, the selectivity with respect to a sample improves, so that the wavelength width of the light irradiated to a sample is small. For this reason, it has been attempted to use a laser as a light source. If a laser is used as the light source, monochromatic light having a high intensity can be obtained, and measurement with high detection sensitivity and good selectivity is possible.
JP-A-5-307003

  In a specific wavelength light irradiation means using a discharge lamp as a light source and a wavelength selection means such as a grating, the light extracted by the grating or the like usually has a certain wavelength width. In order to increase the sensitivity of the measurement, it is necessary to increase the intensity of the irradiation light on the sample. However, as a means for increasing the irradiation light intensity, the bandwidth of the selected wavelength may be increased. However, since the wavelength purity is lowered by widening the bandwidth, the selectivity to the measurement sample is impaired in both the absorbance detector and the fluorescence detector. In addition, in a fluorescence detector, in a sample where the excitation wavelength is close to the fluorescence wavelength, a part of the excitation light is incident on the photodetector in the spectroscope on the fluorescence detection side and the background level of the sample fluorescence is high. As a result, noise may increase and the S / N ratio may decrease.

  Even if an attempt is made to increase the aperture angle of the condensing system of the light source in order to increase the amount of light irradiated to the sample, the aperture angle of the high bundle irradiated to the sample also increases. Moreover, even if the aperture angle of the light beam to the sample is reduced, the image of the light source on the sample is enlarged. In the case of absorbance detection, if the aperture angle of the light flux to the sample is large, the optical path length of the sample cannot be increased, and if the image on the sample becomes large, light that protrudes from the sample and is not used is generated. / N may be impaired. In the case of a fluorescence detector, if the aperture angle of the light beam to the sample is large or the image on the sample is large, the background light level increases due to increased scattering of incident light on the inner wall of the cell. Will increase.

  On the other hand, if a laser that can extract parallel light is used as the light source, it can be focused on a minute point with a small aperture angle and can enter a minute cell, so the above-mentioned problems can be avoided and the sensitivity can be increased. However, in the case of a laser, the wavelength that can be oscillated is limited, so that it can be used only for a specific analysis target.

  The present invention has been made to solve the above problems, and an object thereof is to provide a spectroscopic detection device having both high sensitivity detection and a wide wavelength selection range.

  In order to solve the above problems, the spectroscopic detection device of the present invention uses a light source having a continuous spectrum, wavelength selection means for splitting light emitted from the light source, and light obtained by the interaction between the split light and the sample. A spectroscopic detection apparatus having a light detection means for detecting has means for introducing laser light into a sample.

  In the case where the interaction between the dispersed light and the sample is absorption by the sample, it is an absorbance detector, and in the case of fluorescence emission by the sample, it is a fluorescence detector.

  According to the present invention, since a light source having a continuous spectrum and a laser light source are provided as light sources, high sensitivity detection by a laser light source is possible and a wavelength selection range is widened by using a continuous wavelength light source. It is possible to expand the scope of analysis at the same time. Therefore, a highly sensitive and versatile spectroscopic detection device can be realized with a single device.

  The present invention has a continuous wavelength light source, a spectroscope that splits light emitted from the light source, and a photodetector that detects interaction between the sample and the split light, for example, transmitted light after the sample absorbs light. Then, a laser light source is installed, the sample is irradiated with monochromatic light from the laser light source, and the transmitted light after being absorbed by the sample is introduced into the photodetector. As the continuous wavelength light source, a deuterium lamp, a xenon lamp or the like can be used. A grating can be used as the spectroscope. As the photodetector, a detector such as a photodiode or a photomultiplier can be used. As the laser light source, various lasers such as a semiconductor laser, a He—Cd laser, and a YAG laser can be used according to a necessary wavelength, and a tunable laser can also be used.

  It sets so that the light disperse | distributed with the spectroscope and the light irradiated from the laser light source may advance the same optical path from the point in front of a sample. When high-sensitivity detection is necessary, light from a laser light source is introduced into an optical path passing through the sample, and when measurement in a wide wavelength range is necessary, light from a spectroscope is introduced into the sample. In order to switch between the light from the laser light source and the light from the spectroscope, a movable mirror is installed on the optical path in front of the sample, and the light from the light source introduced into the sample is switched by controlling the position of the mirror. Do.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of an absorbance detector according to a first embodiment of the present invention. The absorbance detector according to the present invention includes a deuterium lamp 1, mirrors 3, 4, 5, a slit 6, a planar grating 7, a planar mirror 9, a sample cell 11, a photodiode 13, and a laser 15.

  The light emitted from the deuterium lamp 1 which is a continuous wavelength light source is condensed on the slit 6 by the mirror 3. The light that has passed through the slit 6 is applied to the planar grating 7 by the mirror 4, and the light dispersed by the planar grating 7 is collected on the sample cell 11 by the mirror 5. The sample cell 11 can be irradiated with light of a specific wavelength by rotating the planar grating 7. A sample is sealed or passed through the sample cell 11, and the absorbance of the sample can be measured by measuring the intensity of light transmitted through the sample with a photodiode 13 which is a photodetector. A laser 15 is installed at a position perpendicular to the optical path from the mirror 5 to the sample cell 11.

  The plane mirror 9 is movable, and when it is at the position indicated by the dotted line, the light dispersed from the mirror 5 reaches the sample cell 11 and the absorbance of the sample can be measured in a wide wavelength range. At this time, the light from the laser 15 is reflected by the flat mirror 9 and does not reach the sample. When the plane mirror 9 is at the position indicated by the solid line, the light from the laser 15 is reflected by the plane mirror 9 and reaches the sample cell 11, and the absorbance of the sample is measured. Since the light emitted from the laser 15 can be focused on a minute point with a small aperture angle and incident on the sample cell 11, highly sensitive detection is possible. At this time, the light from the mirror 5 is reflected by the flat mirror 9 and does not reach the sample. The plane mirror 9 can be moved to a solid line position or a dotted line position by rotating it by a motor.

  When the laser 15 having a large beam divergence angle such as a semiconductor laser is used, a lens is inserted between the plane mirror 9 and the laser 15 so that the laser beam 15 is focused on the sample cell 11. In FIG. 1, the light from the mirror 5 and the light from the laser 15 are switched by a movable plane mirror 9, but the position of the mirror is fixed by using a dichroic mirror and the deuterium lamp 1. It is also possible to switch the light source by switching on / off of the laser 15.

  In FIG. 1, the light introduction position from the laser 15 is between the mirror 5 and the sample cell 11. However, the light introduction position from the laser 15 is not limited to this. When it is set to the 1 side, the light from the laser 15 can be incident on the sample cell 11 by aligning the rotational position of the planar grating 7 with the wavelength of the light from the laser 15 and adjusting the wavelength to be separated. If the light from the laser 15 cannot be fully drawn into the sample cell 11 due to the influence of the mirror or grating between the mirror 9 and the sample cell 11, a lens is installed between the laser 15 and the flat mirror 9. Correction may be performed so that the focus of light from the sample cell 11 is focused on the sample cell 11.

  A second embodiment provided by the present invention is as shown in FIG. The second embodiment is applied to a fluorescence detector, and includes a xenon lamp 21, a lamp condensing mirror 22, an excitation side entrance slit 24, an excitation side grating 25, an excitation side exit slit 27, an excitation side mirror 28, and a sample. The cell 30, the fluorescence side mirror 32, the fluorescence side entrance slit 33, the fluorescence side grating 35, the fluorescence side exit slit 36, the photomultiplier tube 38, and the laser 40 are configured.

  The light emitted from the xenon lamp 21 which is a continuous wavelength light source is condensed on the excitation side entrance slit 24 by the lamp condensing mirror 22 made of a toroidal mirror, and the light passing through the excitation side entrance slit 24 is made on the excitation side made of a concave grating. Dispersed by the grating 25, light having a specific wavelength is collected on the excitation-side exit slit 27. The light that has passed through the excitation-side exit slit 27 is condensed on the sample cell 30 by an excitation-side mirror 28 that is a toroidal mirror. By rotating the excitation side grating 25, the sample cell 30 can be irradiated with light of a specific wavelength. A sample is sealed or passed through the sample cell 30, and the fluorescence emitted from the fluorescent material in the sample excited by the excitation light is transmitted to the fluorescence side entrance slit 33 by the fluorescence side mirror 32 formed of a toroidal mirror. The light that has been collected and passed through the fluorescence side entrance slit 33 is dispersed and collected by the fluorescence side grating 35 onto the fluorescence side exit slit 36. The intensity of light transmitted through the fluorescence side emission slit 36 is measured by a photomultiplier tube 38 to measure the amount of fluorescence of the sample. The laser 40 is placed on the opposite side of the excitation side mirror 28 across the sample cell 30 on the optical axis connecting the excitation side mirror 28 and the sample cell 30, and the light from the laser 40 is the light from the excitation side mirror 28. The light enters the sample cell 30 from the opposite side. The fluorescence emitted from the fluorescent substance in the sample excited by the light from the laser 40 follows the same optical path as the fluorescence emitted by the light from the excitation side mirror 28, and the intensity is measured by the photomultiplier tube 38. . When the xenon lamp 21 is used as a light source, the laser 40 is turned off, and when the laser 40 is used as a light source, the xenon lamp 21 is turned off to switch the light source.

  When using a laser 40 having a large beam divergence angle, such as a semiconductor laser, a lens is inserted between the laser 40 and the sample cell 30 so that the light from the laser 40 is condensed on the sample cell 30. Correct as follows. The method of introducing light from the laser 40 may be at any position of the optical system on the excitation side by the same method as the absorbance detector of the first embodiment.

  The present invention can be applied to a detector of an analyzer that performs qualitative and quantitative analysis of a sample by detecting the absorbance and fluorescence intensity of the sample such as liquid chromatography.

1 is a schematic configuration diagram of an absorbance detector according to a first embodiment of the present invention. It is a schematic block diagram of the fluorescence detector of the 2nd Example of this invention. It is a schematic block diagram of the conventional absorbance detector.

Explanation of symbols

1 Deuterium lamp 3, 4, 5 Mirror 6 Slit 7 Planar grating 9 Plane mirror 11 Sample cell 13 Photo diode 15 Laser 21 Xenon lamp 22 Lamp condensing mirror 24 Excitation side entrance slit 25 Excitation side grating 27 Excitation side exit slit 28 Excitation side Mirror 30 Sample cell 32 Fluorescence side mirror 33 Fluorescence side entrance slit 35 Fluorescence side grating 36 Fluorescence side exit slit 38 Photomultiplier tube 40 Laser 41 Light sources 43, 44, 45 Mirror 47 Slit 49 Grating 51 Sample cell 53 Photo detector

Claims (3)

Laser light in a spectroscopic detection apparatus having a light source having a continuous spectrum, a wavelength selection means for splitting light emitted from the light source, and a light detection means for detecting light obtained by the interaction between the split light and the sample A spectroscopic detection device comprising means for introducing the sample into the sample. 2. The spectroscopic detection device according to claim 1, wherein the interaction between the light and the sample is absorption by the sample, and the spectroscopic detection device is an absorbance detector. The spectroscopic detection device according to claim 1, wherein the interaction between the light and the sample is fluorescence emission by the sample, and the spectroscopic detection device is a fluorescence detector.

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