JPH0319503B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to the fluorescence analysis of liquid or gaseous samples, particularly those containing a large amount of impurities and having low light transmission properties, such as the analysis of nuclear fuel material in nuclear fuel reprocessing solutions. The present invention relates to a fluorescence analyzer suitable for analysis conditions with low yield.

[Background of the invention]

Fluorescence analysis is widely used as a highly sensitive analysis method for trace substances. Conventionally, for example, W. Canpen,
K. Beckman Microchimica Acta (W.
Campen, K. Ba¨chman: Mikrochimica Acta)
1979, 159-170 measured the fluorescence intensity of uranium in seawater using a laser as an excitation light source, and obtained a value of 10 ^-1 ng/ml as the detection limit for uranium.
Since this analysis method utilizes light for input and output, it has the advantage of being able to perform on-site analysis through an optical window, and also to allow remote analysis of locations distant from the analyzer body using optical fibers.

However, fluorescence analysis is originally a method for analyzing analytes in clean solvents, and when the concentration of impurities is high and the excitation light and fluorescence itself are attenuated, quantification becomes difficult. Especially in reprocessing solutions, liquid transparency is poor due to FPs and cruds, and the transparency of the sample cell may be reduced due to radiation damage and crud adhesion caused by FPs, so traditional fluorescence analysis methods are I couldn't deal with it.

As mentioned above, conventional general fluorescence analysis methods cannot be applied under conditions such as low transparency of the sample or sample cell, high impurity concentration, or when these change over time. I couldn't take advantage of it.

[Purpose of the invention]

An object of the present invention is to provide a fluorescence analyzer capable of quantitative analysis even under conditions where sample transparency and sample cell transparency are low or change over time.

[Summary of the invention]

The fluorescence analysis method of the present invention irradiates a sample liquid with excitation light to generate Raman light of the solvent and fluorescence of the analyte, separates the generated Raman light of the solvent and fluorescence of the analyte, and separates the Raman light of the solvent and the fluorescence of the analyte. detect the intensity of
Next, the ratio of the Raman light intensity of the solvent to the fluorescence intensity of the analyte is determined, and the analyte in the sample liquid is analyzed from that ratio.

Further, the fluorescence analysis device of the present invention includes an excitation light source, a sample cell, a spectrometer that separates the Raman light of the solvent and the fluorescence of the analyte generated from the sample cell, and the Raman light of the solvent and the fluorescence of the analyzer. It is characterized by comprising a light intensity detector for measuring the intensity, and a data processing device that calculates the ratio between the Raman light intensity of the solvent and the fluorescence intensity of the analyte, and calculates the concentration or content of the analyte from the intensity ratio. shall be.

Generally, when a sample is irradiated with excitation light, the fluorescence of the solvent and the Raman light of the analyte can be ignored.
Therefore, the Raman light and fluorescence generated from the sample represent the Raman light of the solvent and the fluorescence of the analyte, respectively. However, for example, when the Raman light of an analyte is a problem, the wavelength deviation of the Raman light differs depending on the substance, and this characteristic can be utilized to discriminate the Raman light of the solvent.

Therefore, since impurities such as FP and cladding affect Raman light and fluorescence in the same way, these effects can be removed by calculating the ratio of the Raman light intensity of the solvent to the fluorescence intensity of the analyte. Ru. As a result, according to the present invention, it is possible to analyze the concentration of the analyte.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the device configuration of this embodiment. The analyzer main body of this device consists of a laser 1 as an excitation light source, a spectrometer 2, a light intensity detector 3, and a data processing device 4, and is installed in a room where operators perform analysis operations or maintenance work. , the wall 5 has radiation-resistance capability in a reprocessing plant. The excitation light source does not necessarily have to be a laser; a white light source may be passed through a spectroscope to make it monochromatic, or a filter can be used instead of the spectroscope to make it monochromatic. However, for observation of Raman light, it is desirable to have sufficiently monochromatic and strong excitation light, so from this point of view,
A laser is most suitable as an excitation light source. The type of laser is selected to have an excitation light wavelength that increases the fluorescence yield of the analyte. The spectrometer 2 needs to have little stray light, and the light intensity detector 3 needs to have high sensitivity. From this point of view, a photomultiplier tube is most suitable, but a multichannel detector with an intensifier can be used for simultaneous spectroscopy. The data processing device 4 has a differential processing function for flattening the background in addition to integration processing, smoothing, etc.

The analyzer main body and the sample cell are connected to the light transmitting fiber 6.
and a light receiving fiber 7. The analysis cell section is composed of a fiber connector 8, a cell cover 9, an irradiation mirror 10, a condensing mirror 11, a sample cell 12, and a fiber shield 13, and is installed at an analysis location in a plant. Excitation light 14 guided from the laser 1 through the light transmission fiber 6 is reflected by the irradiation mirror 10, enters the sample cell 12 through the hole in the condensing mirror 11, and excites the sample 15. Fluorescence of the analyte thereby generated from the sample16
and the Raman light 17 of the solvent are focused by a focusing mirror 11 and sent to a light receiving fiber. FAIBA SHIYAHEI 13
has the role of suppressing radiation from the sample 15 and protecting the light transmitting fiber 6 and the light receiving fiber 7.
The cell cover 9 has a light function.

When viewed from the side of FIG. 1, the relationship between the sample cell section and the analysis location is as shown in FIG. 2.

A sampling pipe 19 is connected to the process pipe 18 and the plant fluid (arrow in the figure) is transferred to the sample cell 12.
sample 15. During analysis, the sampling valve 20 is closed to stop the flow if necessary. In the case of reprocessing solutions, a process piping shield 21 is installed in the process piping to reduce radiation intensity. The cell cover 9 should not accidentally cover the sample cell 12.
(Made of non-fluorescent quartz) It also has a function to prevent the sample from leaking outside if it is damaged.

To summarize the analysis procedure of this example, first open the sampling valve 20 and then open the sampling pipe 19.
After that, the sampling valve 20 is closed to keep the fluid in the sampling pipe stationary. These operations are performed remotely. Next, from the laser 1, the light transmission fiber 6 is connected to the irradiation mirror 1.
0 to the sample 1 in the sample cell 12.
5. At this time, the fluorescence 16 and Raman light 17 of the analyte generated from the sample 15 are guided to the spectrometer 2 via the condensing mirror 11 and the light transmission fiber 7, and the separated light is detected by the light intensity detector 3. The detected optical spectrum is subjected to differential processing, etc., as necessary by the data processing device 4, and the concentration of the analyte is quantified. When one analysis is completed, the sampling valve 20 is opened again to begin the next sampling.

Although not clearly shown in FIG. 1, the fiber connector on the light transmission side is equipped with a lens for restoring the divergence of light at the end of the fiber. Also, on the light receiving side, if necessary, a lens is attached so that the collected light can efficiently enter the fiber.

Next, the measurement principle of this embodiment will be explained using FIG. 3.

Considering in one dimension the case where fluorescence and Raman light are observed from the excitation light incidence side as shown in Figure 3, if the excitation light intensity is I _i , the fluorescence intensity of the analyte I _F ,
The Raman light intensity I _R and the transmitted light intensity I _O of the solvent are respectively given by the following equations.

I _F =I _i φ _F (λ _E )ε _n (λ _E )C _n exp{
−μ _ce (λ _E ) + μ _ce (λ _F ))t}×{1−exp(
−μ _s (λ _F )l)}/μ _s (λ _F )……(1) I _R =I _i φ _R (λ _E )C _sel exp{−(μ _ce
(λ _E ) +μ _ce (λ _R ))t}×{1−exp(
μ _s (λ _R )l)}/μ _s (λ _R )……(2) I _O =I _i exp{−2μ _ce (λ _E ) t−1/2μ _s (λ _E )l} ……( 3) Here, μ _ce (λ)t≡μ _q (λ)t _q + μ _cr (λ)t _cr ……(4) μ _s (λ)≡C _spl (ε _spl (λ _E ) + ε _spl (λ) ) +C _cr (ε _cr λ _E )+ε _cr (λ)) +C _FP (ε _FP (λ _E )+ε _FP (λ)) +C _n (ε _n (λ _E )+ε _n (λ)) ……(5) μ: Attenuation coefficient ε: Absorption coefficient C: Concentration l: Sample cell optical path length t=t _q + t _cr t _q : Quartz thickness t _cr : Adhesive dirt (cladding thickness) φ _F : Fluorescence yield φ _R : Raman Light yield λ: wavelength subscript: ce: sample cell, s: sample, FP: impurity (FP), Cr: dirt (crud), q: quartz,
sol: solvent, m: analyte, F: fluorescence, R:
Raman light, E: excitation light μ _s (λ _F ) μ _s (λ _R ) + C _spl (ε _spl
(λ _F )−ε _spl (λ _R )) +C _cr (ε _cr (λ _F )−ε _cr (λ _R )
)+C _FP (ε _FP (λ _F )−ε _FP (λ _R )) +C _n (ε _n (λ _F )−ε _n (λ _R ))=
μ _s (λ _R ) + Δμ _s,FR ...(6) Here, Δμ _s,FR = μ _s (λ _F − μ _s (λ _R ) Similarly, μ _s (λ _E ) = μ _s (λ _R ) + Δμ _s,ER …(7) μ _ce (λ _F ) μ _ce (λ _R ) + Δμ _ce,FR …(8) μ _ce (λ _E ) = μ _ce (λ _R ) + Δμ _ce,ER … …(9) Therefore, from equations (1), (2), and (6) to (9), I _F /I _R φ _F (λ _E )ε _n (λ _E )C _n exp{−(2
μ _ce (λ _R +Δμ _ce,ER +Δμ _ce,FR )t}/φ _R (λ _E C _sp
l exp{−(2μ _ce (λ _R )Δμ _ce,ER )t} × [1−exp{−(μ _s (λ _R )+Δμ _s,F
R )l}〕μ _s (λ _R )／{1−exp(−μ _s (λ _R )l}{
μ _s (λ _R )＋Δμ _s,FR }……(10) Therefore, if μ _ce ≫Δμ _ce , μ _s ≫Δμ _s …(11), then equation (10) becomes I _F /I _R ≒φ _F (λ _E )ε _n (λ _E )C _n /φ _R (λ _E )C _spl ≒
kC _n ...(12) (k: constant) That is, the ratio I _F / _IR of the fluorescence intensity I _F of the analyte to the Raman light intensity I _R of the solvent is proportional to the concentration C _n of the analyte.

As explained above, under conditions where the transparency of the sample cell and sample is low due to impurities in the sample, (11)
Since the condition of the formula holds true, C _n from the measured value of I _F /I _R
can be found.

Δμ _s,FR and Δμ _ce,FR come into play for the error in equation (12). That is, it is better that the fluorescence wavelength and the Raman wavelength are close to each other. When the fluorescence rides on the tail of the Raman light, it can be applied using the above-mentioned differential processing data processing device. Since the fluorescence intensity itself increases when excited with a wavelength with a strong excitation spectrum, the optimal excitation light wavelength may be determined based on these considerations. FIG. 4 shows an example spectrum of a nitric acid solution of UO ₂ ²⁺ .

As explained above, according to this example, conditions such as a reprocessing solution where the transparency of the liquid is low due to impurities, and the transparency of the sample cell is also reduced due to adhesion of impurities (cruds) and radiation damage. The method below also has the advantage that the concentration of the analyte can be determined by calculating the intensity ratio between the fluorescence intensity of the analyte and the Raman light intensity of the solvent. In addition, by connecting the analyzer body inside the radiation-shielding wall and the sample cell section installed at the analysis location via an optical fiber, it is possible to safely operate and maintain the analytical equipment. Furthermore, since only the sample cell section is installed in a location where radiation is strong, normal maintenance is not required, and even if damage or deterioration should occur, remote replacement can be easily performed.

In addition, the method of calculating the intensity ratio of fluorescence and Raman light requires correction using a so-called internal standard, so it is important to consider the arrangement of the optical system that collects the fluorescence and Raman light, and the risk of radiation damage to the sample cell. It has the advantage that it can be used without depending on non-uniformity such as cladding adhesion. Furthermore, by taking the intensity ratio, it is not affected by the attenuation of the excitation light intensity due to the optical fiber or fluctuations in the excitation light intensity.

Note that although the above explanation is based on the condition that the analyte is dissolved in the solvent, the analyte does not necessarily have to be in a dissolved state, and the same analysis method can be applied even when it is dispersed in the liquid. The content of the analyte can be determined by In that case, the difference in fluorescence intensity from the dissolved state is corrected in data processing.

Other embodiments of the invention are shown below.

FIG. 5 shows the apparatus configuration of this embodiment. The structure of the analyzer body is the same as that of the previous embodiment (FIG. 1). In this embodiment, the excitation light 14 is guided directly to the sample cell 12 without using a fiber. A dark light tube 22 is installed in this optical path to prevent stray light, and is connected to the analysis cover 9 with a dark light tube connector 23. Fluorescence light 16 and Raman light 17 generated from the sample 15 are reflected and condensed by a spherical mirror 24 and guided to the light transmitting fiber 7 via a lens 25.

In this example, a spherical mirror is used to condense fluorescence and Raman light, so that the light emitted omnidirectionally from the excitation light incident point of the sample cell can be efficiently condensed.
It has the advantage of being observable. In addition, since the excitation light does not pass through the fiber, it also has the advantage that no attenuation occurs along the way.

Further embodiments of the invention will be described below.

The device configuration of the sample cell section is shown in FIGS. 6 and 7. FIG. 7 is a front view of FIG. 6.

The excitation light 14 is guided into the cell cover 9 through the light transmission fiber 6, and is split into light for the sample cell 12 and light for the reference cell 25 via the half mirror 24, and the latter is further divided into light for the sample cell 12 and light for the reference cell 25. 24, it is divided into front and rear parts of the radiation shield 26. The reference cell 25 is connected at the bottom, and the interior thereof is filled with a purified solvent 27. Fluorescence and Raman light generated from the sample cell 12 and the reference cell 25,
Raman light generated from before and after the radiation shield 26 is focused by a condensing mirror 11 each having a pore through which excitation light passes, and sent through a light receiving fiber 7 to a spectrometer in the main body of the analyzer. Although not shown in FIGS. 6 and 7, the light sent in this manner is divided and taken into a spectrometer using an automatic optical element switching mechanism, and is used for data processing. Of course, a spectrometer and a detector may be provided for each of the three receiving fibers.

Here, the information retrieved from the sample cell is the same as in the other embodiments. That is, the concentration of the analyte is determined using information from the sample cell 12. Hereinafter, focusing on the Raman light of the solvent, from the information of the sample cell 12 and the reference cell 25, the FP concentration during the process,
We will explain how to estimate the amount of crud and radioactivity. The Raman light intensity from the sample cell 12 is (a)FP
Decrease in light transmittance of the cell due to radiation damage, (b)
In addition to the decrease in light transmittance due to the absorption of excitation light and Raman light by the FP, the light transmittance of the cell is also affected by (c) the adhesion of the cladding to the cell wall. Regarding the reference cell 25 on the side that is in contact with the sample cell 12, since it receives radiation from the FP within the sample cell 12, the cell itself receives radiation damage to the same extent as the sample cell 12, and the light transmittance of the cell decreases. . The other reference cell 25 placed outside the radiation shield 26 is not affected by this. Therefore, the intensities of the two types of Raman light from both reference cells are compared to determine the decrease in light transmittance due to radiation damage. Since there is a certain relationship between the amount of radioactivity and the decrease in light transmittance due to radiation damage, the amount of radioactivity of FP can be determined. Furthermore, since the FP concentration and the amount of light radioactivity are proportional as a first approximation, the FP concentration can be determined from the amount of FP radioactivity.

Next, we will explain how to estimate the amount of cladding. If we know the FP concentration, we can understand the decrease in light transmittance due to (b), that is, due to FP. The Raman light intensity of the solvent obtained from the prototype cell 12 is influenced by the above three light transmittances. On the other hand, Radiation Shiyahei 2
The Raman light intensity of the solvent from the reference cell placed outside 6 shows the true value without any influence. Therefore, from the Raman light intensity of the sample cell 12, the Raman light intensity of the unaffected reference cell, the light transmittance decrease due to radiation damage, and the light transmittance decrease due to FP concentration, the decrease in light transmittance due to the cladding is determined. Can be done. Since there is a certain relationship between the amount of cladding and the decrease in light transmittance, the amount of cladding can also be determined. Therefore, information other than the amounts of U and Pu in the process can be obtained and can be utilized for plant operation control. Furthermore, since the progress of radiation damage and crud deposition on the sample cell can be monitored, it is possible to know when the sample cell section should be remotely maintained or replaced. To extract information from the reference cell, transmitted light may be used instead of Raman light. Unlike the sample cell, in the case of a reference cell containing only purified solvent, there is no risk that the intensity of transmitted light will become weak due to excessive absorption and attenuation along the way. Note that in the present invention, differences in peak intensity may occur due to differences in the accuracy of the light intensity detector, but this is essentially no problem.

〔Effect of the invention〕

According to the present invention, by determining the intensity ratio of the fluorescence of the analyte and the Raman light of the solvent, the concentration of a trace amount of the analyte can be analyzed on the spot under analysis conditions where the transparency of the sample cell or sample is poor. have the advantage of being able to

[Brief explanation of drawings]

Figures 1 and 2 are schematic diagrams showing the configuration of a fluorescence analyzer according to an embodiment of the present invention, Figure 3 is a cross-sectional plan view of a sample cell for explaining the principle, and Figure 4 is an example of spectrum measurement. FIGS. 5 to 7 are schematic diagrams showing apparatuses according to other embodiments. DESCRIPTION OF SYMBOLS 1... Laser, 2... Spectrometer, 3... Light intensity detector, 4... Data processing device, 6... Light transmitting fiber, 7... Light receiving fiber, 10... Irradiation mirror,
11... Concentrating mirror, 12... Sample cell, 14...
... Excitation light, 14 ... Sample liquid, 16 ... Fluorescence of analyte, 17 ... Raman light of solvent, 18 ... Process piping, 19 ... Sampling pipe, 25 ...
...Reference cell.

Claims (1)

[Claims] 1. A sample liquid is irradiated with excitation light to generate Raman light of the solvent and fluorescence of the analyte, and the generated Raman light of the solvent and fluorescence of the analyte are separated, and the intensity of each is determined. A fluorescence analysis method characterized in that the ratio of the Raman light intensity of the solvent to the fluorescence intensity of the analyte is determined, and the analyte in the sample liquid is analyzed from that ratio. 2. The fluorescence analysis method according to claim 1, wherein the substance to be analyzed is a nuclear fuel material. 3 An excitation light source, a sample cell, a spectrometer that separates the Raman light of the solvent and the fluorescence of the analyte generated from the sample cell, a light intensity detector that measures the intensity of the Raman light of the solvent and the fluorescence of the analyte, and the solvent. 1. A fluorescence analysis device comprising: a data processing device that calculates the ratio of the Raman intensity of the analyte to the fluorescence intensity of the analyte, and calculates the concentration or content of the analyte from the intensity ratio. 4 An excitation light source, an irradiation mirror that reflects the excitation light and irradiates it onto the sample cell, a sample cell, and a condenser that focuses Raman light of the solvent and fluorescence of the analyte generated from the sample cell and sends the light to the spectrometer. A spectrometer that separates the Raman light of the solvent and the fluorescence of the analyte coming from the optical mirror, a light intensity detector that measures the intensity of the Raman light of the solvent and the fluorescence of the analyte, and a Raman light intensity of the solvent and the fluorescence of the analyte. Find the ratio to the fluorescence intensity,
and a data processing device that calculates the concentration or content of the analyte from the intensity ratio. 5. The fluorescence analysis device according to claim 4, wherein the irradiation mirror and the condensing mirror are metal mirrors. 6. A device group including an excitation light source, a spectrometer, a light intensity detector, and a data processing device and a device group including an irradiation mirror, a sample cell, and a condensing mirror are installed separately through a radiation shielding wall. A fluorescence analysis device according to claim 5. 7. Fluorescence analysis according to claim 4 or 6, characterized in that light is transmitted from the excitation light source to the irradiation mirror and from the condensing mirror to the spectrometer using an optical fiber. Device.