JPS6135937Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a sensitivity calibration device for a fluorescence spectrometer.

Methods for calibrating the sensitivity of a fluorescence spectrometer include a method using a standard light source, a method using a standard fluorescent substance, and a method that uses Raman scattered light to keep the sensitivity of the device constant. The present invention relates to an apparatus using a method that utilizes this Raman scattered light.

The method using Raman scattered light measures the intensity of Raman scattered light emitted by the solvent of the sample and adjusts the sensitivity of the photoelectric conversion element or the gain of the amplification system so that the intensity remains constant. It was difficult to accurately measure the Raman scattered light due to blind fluorescence contained in the blank. The blind fluorescence exhibits a flat wavelength distribution as shown in FIG. 1, and the Raman scattered light is on top of the blind fluorescence, using it as a baseline. Therefore, it is not possible to separate the blind fluorescence and the Raman scattered light simply by measuring at the center wavelength position of the Raman scattered light, and the blind fluorescence level is not always constant because it depends on various impurities contained in the solvent. This interferes with the upper sensitivity calibration. Therefore, in order to perform sensitivity calibration using Raman scattered light, it is necessary to measure the scattered light in a certain wavelength range before and after the Raman scattered light each time to obtain the curve shown in Figure 1. However, if sensitivity calibration using Raman scattered light is attempted automatically, the device configuration will become very complicated.

The present invention is to obtain a profile of Raman scattered light that broadly includes the base portion as shown in Figure 1 above, and thereby measure the level of only the Raman scattered light without removing blind fluorescence. Therefore, the present invention aims to provide an apparatus capable of performing sensitivity calibration.

FIG. 2 is a plan view schematically showing the fluorescence spectrometer. L is a light source, M1 is an excitation light spectrometer, and C is a sample cell that is irradiated by light exiting the spectrometer M1. M
2 is a fluorescence spectrometer, and various lights emitted in a direction perpendicular to the excitation light that entered the sample cell C enter M2,
The light separated by M2 passes through the exit slit S and enters the photoelectric conversion element P.

In the present invention, the exit slit S in FIG. 2 has a special structure so that Raman scattered light and blind fluorescence can be measured separately. The principle will be explained with reference to FIG. FIG. 3 shows an extracted range of a certain width centered on the Raman scattered light in FIG. 1. Now, as exit slits, we use a central slit S1 and three slits S2 and S3 arranged on both sides of the center slit S2 and S3, which are spaced apart by wavelength difference by ΔW so as to be located on both side slopes of the peak of Raman scattered light. At the same time, if S1 is removed, Ia′,
Light having a light intensity written as Ib' is incident on the photoelectric conversion element P. Therefore, the slit width of S2 and S3 is set to S1.
The output of P at this time can be regarded as (Ia'+Ib')/2. Next, by removing the slits S2 and S3 and using the slit S1, the height Ic' of the center of the Raman scattered light can be measured. As is clear from the figure, Ic′ is the intensity of the Raman scattered light superimposed on the blind fluorescence of intensity Id, and the true Raman scattered light intensity Ic is Ic′−Id′, and similarly, The true intensities Ia and Ib of the Raman scattered light on both sides Δw of the center of the Raman scattered light are Ia = Ia' - Id and Ib = Ib' - Id, respectively, but the ones that can be directly measured are Ia', Ib', and Ic. ′. Therefore, Ic'-(Ia'+Ib')/2 can be calculated using an arithmetic circuit. Here, the level of blind fluorescence can be considered to be almost horizontal in the range of ΔW around the Raman scattered light, so if this level is Id, then Ia' = Ia +
Id, Ib′=Ib+Id, Ic′=Ic+Id, so Ic′−(Ia′+Ib′)
/2=Ic-(Ia+Ib)/2=Io...(1) The above equation does not include the blind fluorescence level Id. Therefore, Io is completely proportional to the Raman scattered light intensity, and correct sensitivity calibration can be performed by adjusting the sensitivity of the photoelectric conversion element P or the gain of the subsequent amplifier circuit so that Io remains constant. .

FIG. 4 shows the exit slit (S in FIG. 2) of a fluorescence spectrometer according to an embodiment of the present invention. 1 is a slit plate in which slits S1, S2, and S3 are opened. Both the widths of slits S2 and S3 are the same as slit S1.
The distance between the centers of each slit corresponds to the wavelength difference ΔW in FIG. A mask 2 that can be moved up and down is provided on the front side of the slit plate 1. This mask has a downward convex shape, and in the position shown in the figure when it is pulled upward, the slit S1 is covered and closed by the downward protrusion in the center, and the slits S2 and S3 on both sides are open. When the mask is lowered, all the slits are covered, but since the window 3 is cut in the position opposite to the slit S1,
At this time, slits S2 and S3 are closed and slit S1 is opened.

When the mask 2 is moved up and down at high speed, the amount of light incident on the photoelectric conversion element P changes as Ic' and (Ia'+
Ib')/2, and the output of P pulsates.
Therefore, after appropriately amplifying this output, a pulse signal synchronized with the top and bottom of mask 2 is used to convert the amplified output into
The signal corresponding to Ic′ and the signal corresponding to (Ia′+Ib′)/2 are sampled separately, and after smoothing both, they are applied to a subtraction circuit to generate a DC signal corresponding to the former Ic′. By subtracting the DC signal corresponding to the latter (Ia'+Ib')/2 from the above equation (1), Io can be found. Therefore, this Io is used as the sensitivity adjustment signal of the photoelectric conversion element or the automatic gain signal of the amplifier circuit.

As mentioned above, the present invention can also be used to control the sensitivity to be constant at all times, but it can also be used to control the monthly or yearly sensitivity of a phenol monitoring device in wastewater that detects phenol using fluorescence. It is also used when it comes to calibration. When detecting phenol using fluorescence, the excitation light wavelength is 254 to 295 mm.
Since the line is short, the level of blind fluorescence due to other impurities in the liquid to be measured becomes high, and correct sensitivity calibration is completely impossible with a method that measures the scattered light intensity only by the position of the Raman line. According to the present invention, a signal accurately proportional to the intensity of Raman scattered light can be obtained without being affected by blinding fluorescence, making it possible to calibrate the sensitivity correctly. It is extremely effective.

[Brief explanation of the drawing]

Figure 1 is a graph showing the overlap between Raman scattering and blind fluorescence, Figure 2 is a plan view of the fluorescence spectrometer, and Figure 3 is a graph of the profile of Raman scattering to explain the principle of the present invention. , FIG. 4 is a front view of a slit in an embodiment of the present invention. 1... Slit plate, 2... Mask, 3... Window drilled in the mask, S1, S2, S3... Slit opening.

Claims (1)

[Scope of utility model registration request] The exit slit of the fluorescence spectrometer is composed of three slits: a central slit and slits on both sides of the slit located on the slopes on both sides of the peak of the Raman line, separated by an appropriate wavelength difference. A sensitivity calibration device for a fluorescence spectrometer, which enables switching between covering the slit and covering the slits on both sides, and aligning the center slit with the position of Raman scattered light.