JPH0452426B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting radioactive substances using liquid chromatography. More specifically, the present invention relates to a method for detecting radioactive substances using a stimulable phosphor.

One method of separation analysis is to inject a sample solution into a packed tower (column) packed with an adsorbent, then inject an appropriate solvent to develop the sample, and then collect the sample components as they flow out of the column. Liquid chromatography is known. This liquid chromatography is also used to separate samples containing radioactive substances (substances containing radioactive isotopes), and is used to measure the radiation emitted from the eluate separated by liquid chromatography operations. The separation and identification of radioactive substances in samples is carried out using this method.

Conventionally, a method for measuring radiation emitted from a liquid sample containing a radioactive substance is, for example, by adding a liquid scintillator made by dissolving a solute (fluorescent agent) in an organic solvent to the sample.
Liquid scintillation methods, which involve detecting radiation emitted from a sample as fluorescence, are widely used. In this method, a part of the radiation energy emitted from the radioactive substance in the sample is absorbed by a scintillator, and the fluorescence (instantaneous luminescence) emitted from this scintillator is detected.
This is a method of measuring the radioactivity of the radioactive substance.

The liquid scintillation method described above is also applied to liquid chromatography of samples containing radioactive substances, and by separating a certain amount of the liquid sample flowing out of the column and adding a liquid scintillator, radiation from the sample is removed. measurements are being carried out.

In other words, a sample containing radioactive substances separated and developed by liquid chromatography is collected using a fraction collector, a liquid scintillator is added to each fraction, and the fluorescence emitted from the liquid scintillator is collected using a photomultiplier tube. By detecting and counting the electrical pulses, the radiation dose is measured for each flank, and the radioactive substances in the sample are separated and identified.

In this way, the liquid scintillation method has the advantage of being able to detect radioactivity even when the radiation emitted from radioactive substances is weak radiation such as α-rays and β-rays. It has become a useful tool for measuring radioactivity.

However, when the liquid scintillation method is used in liquid chromatography of samples containing radioactive substances, the sample separated and developed by liquid chromatography is transferred to a fraction consisting of a large number of scintillation measuring vessels (vials). After the sample is collected using a scintillation collector, radiation is detected for each sample volume by measuring each measurement container with a scintillation counter. Therefore, in order to separate and identify radioactive substances in a sample with high precision, it is necessary to increase the number of measurement containers used as flank collectors, which also means that the number of measuring containers used as flank collectors must be increased. This means that the measurement operation becomes complicated.

In addition, in the liquid scintillation method, the scintillator's light emission is caused by the energy of the radiation emitted from the radioactive substance in the liquid sample, which first excites the solvent molecules formed by dissolving the solute (fluorescent agent), and then excites them. This occurs when solute molecules are excited due to collisions between solvent molecules and solute molecules (scintillator). In addition to this process in which radiation energy is transferred from solvent molecules to solute molecules, energy is transferred between solvent molecules due to interactions between solvent molecules in the excited state and solvent molecules in the ground state. This also includes the case where the scintillator is excited after energy is transferred to another solute molecule due to the interaction between the excited solvent molecule and another solute molecule other than the scintillator. Furthermore, this energy transfer occurs not only through interactions between molecules such as collisions, but also when the scintillator absorbs fluorescence emitted from excited solvent molecules or other solute molecules.

Furthermore, during this energy transfer process, the excitation energy may be absorbed by some solvent molecules or other solute molecules and then converted into heat, or the fluorescence emitted from the scintillator may be absorbed into the sample. A quenching phenomenon such as absorption by a light-absorbing substance also occurs at the same time.

The liquid scintillator essential in the liquid scintillation method is expensive and requires separation and purification before reuse. Furthermore, since it is difficult to recover scintillators with high purity, they are not often reused, and this also makes it difficult to reduce measurement costs. Furthermore, there are several problems in the handling of used scintillators containing radioactive elements, such as the difficulty in disposing of them.

Further, since the fluorescent agent used in the liquid scintillation method is an organic substance, the solvents that can be used are limited to organic solvents in most cases. For this reason, radioactive samples do not necessarily dissolve in solvents, and if the sample is poorly soluble in the solvent, it is necessary to select an appropriate solvent or devise a sample preparation method such as emulsifying and suspending the sample. do.

As mentioned above, the light emission mechanism of liquid scintillators is complicated, so the counting efficiency decreases due to the quenching effect of mixed impurities and the sample itself (i.e., the detected radioactivity intensity decreases).
There is a tendency. For example, fluorescence emitted from a scintillator is easily quenched by oxygen dissolved in the scintillator, or if the sample solution is colored, the colored substance also absorbs (ie, quenches) the fluorescence. In addition, if the sample is poorly soluble, it is difficult to make the sample solution into a homogeneous phase, whereas in the case of a sample solution with a heterogeneous phase,
There are problems such as internal absorption of radiation emitted from the sample. Therefore, it is necessary to correct for the quenching caused by the various causes mentioned above to accurately determine the sample counting efficiency, which makes the measurement operation complicated.

Furthermore, in order to prevent a decrease in counting efficiency due to the quenching effect of impurities, contaminants, and colored substances mixed in the sample, careful preparation of the sample is required, and the measurer must have a high degree of skill and experience. is required.
In addition, pretreatment of the sample is required to remove the above-mentioned contaminants.

Furthermore, in the liquid scintillation method, radioactive rays of a sample are measured in real time. In other words, after adding a scintillator to a liquid sample, for a certain period of time (for example, several minutes to several tens of minutes)
It is necessary to continuously measure the luminescence from the scintillator. In this measurement, when the intensity of radiation is low, the measurement time (measurement time) is long, and it cannot be said that the efficiency of measurement and the operating rate of the measuring device are sufficiently high.

Therefore, if the sample consists of a large number of samples as described above, there is a problem that it is difficult to process a large number of samples due to the long waiting time, and it also takes a long time to obtain the results. A problem has arisen. In particular, it is difficult to measure radiation when the radioactive isotope in the sample has a short half-life, and even more difficult when the intensity of the radiation is weak. This also means that the equipment used must be stable for long periods of time (e.g. against dark current drift in photomultiplier tubes), and in order to prevent this This results in either requiring expensive equipment or requiring experience and skill in adjusting the equipment.

The present inventor has conducted intensive research with the aim of solving the above-mentioned problems associated with the conventional liquid scintillation method in liquid chromatography of samples containing radioactive materials. Using a sheet-shaped radiation measuring device that is made up of a stimulable fluorescent material and a stimulable fluorescent material containing a stimulable phosphor integrated in a laminated state, a liquid sample is continuously or continuously moved while the measuring device is moved one after another. It has been discovered that the above-mentioned problems can be solved or the drawbacks can be reduced by utilizing a method of intermittently supplying and depositing radiation energy onto the measuring device and then measuring the radiation energy absorbed by the measuring device. , arrived at the present invention.

Further, in liquid chromatography of a sample containing a radioactive substance, the present inventor has developed a sheet-like radiation absorbing material comprising a liquid retaining member and a stimulable phosphor member containing a stimulable phosphor in a separated state. Using the measuring tool set, while sequentially moving the liquid retaining member, which is one component of the measuring tool set, a liquid sample is continuously or intermittently supplied onto the liquid retaining member and then deposited thereon. The above problems can be solved or the drawbacks can be reduced by using a method of overlapping the liquid retaining member and the stimulable fluorescent member and then measuring the radiation energy absorbed by the stimulable fluorescent member. The inventors have discovered that this can be realized, and have arrived at the present invention.

That is, the present invention provides: (1) a stimulable phosphor member containing a stimulable phosphor under a column filled with an adsorbent so as to receive and hold a liquid sample that has passed through the column; By supplying a sheet-like radiation measuring device consisting of a liquid retaining member provided on the liquid sample and then sequentially moving the radiation measuring device in the plane direction of the sheet, the liquid sample is continuously or (2) A step in which at least a portion of the radiation energy emitted from the radioactive substance held in the radiation measuring device is absorbed by the stimulable phosphor member of the radiation measuring device; ( 3) A step of continuously measuring the radioactivity in the sample by emitting the radiation energy stored in the radiation measuring device as photostimulated light and photoelectrically reading the stimulated light. A method for detecting radioactive substances in a liquid sample using chromatography.

The present invention also provides the following features: (1) A liquid retaining member is supplied under the column filled with the adsorbent so as to receive and hold a liquid sample that has passed through the column, and the liquid retaining member is attached to the column. A step of continuously or intermittently adhering the liquid sample to the retaining member by sequentially moving it in a direction along the surface; (2) a stimulable material containing the liquid retaining member and a stimulable phosphor; a step of causing the stimulable phosphor member to absorb at least a portion of the radiation energy emitted from the radioactive substance held in the liquid retaining member by overlapping the stimulable phosphor member; (3) the stimulable phosphor member; A liquid chromatograph comprising: emitting radiation energy stored in a phosphor member as photostimulated light, and continuously measuring radioactivity in the sample by photoelectrically reading the photostimulated light. There is also a method for detecting radioactive substances in liquid samples using E.

In the sheet-like radiation measuring device used in the present invention, the liquid retaining member and the stimulable fluorescent member, which are the main constituent members, are integrated, that is, the liquid retaining member and the stimulable fluorescent member are integrated in a laminated state. Alternatively, it may be of a separate type (set), that is, a form in which the liquid retaining member and the stimulable fluorescent member are provided separately.

After absorbing radiation, the stimulable phosphor used in the present invention emits light (stimulated luminescence) when irradiated with electromagnetic waves (excitation light) such as visible light and infrared rays.
It has the property of showing. Therefore, a liquid sample containing a radioactive substance is introduced into a liquid retaining member of a radiation measuring device, and then the radiation emitted from the radioactive substance in the sample is absorbed by a stimulable phosphor member, and then the measuring device is By irradiating electromagnetic waves (excitation light) such as visible light and infrared rays, accumulated energy proportional to the radiation dose is released as fluorescence (stimulated luminescence). By photoelectrically reading this fluorescence and converting it into an electrical signal, the radiation emitted from the sample can be measured.

That is, the sheet-like radiation measuring device used in the present invention has both the function of holding a liquid sample and the function of accumulating radiation from the sample and converting it into photostimulated light.

According to the present invention, radioactive substances contained in a liquid sample that is continuously or intermittently supplied can be detected easily and with high precision in liquid chromatography.

That is, for example, a sheet-like radiation measurement device (or liquid-retaining member) is placed horizontally under the column, and the above-mentioned radiation measurement is performed while continuously (or intermittently) dropping or flowing a liquid sample from the column. By first moving the tool horizontally in one direction (X direction), the liquid sample is adsorbed and held on the measuring device in a continuous or discontinuous band shape, and when the band reaches near the end of the measuring tool. After the measuring tool is slightly moved horizontally and in a direction perpendicular to the X direction (Y direction), the measuring tool is then moved in the opposite direction in the X direction. Then, by repeatedly moving the sheet radiation measurement device back and forth in the X direction while appropriately performing such slight movements in the Y direction, the liquid sample is spread onto the liquid retaining member in a continuous or discontinuous strip. It can be held as Note that the operation of moving the measuring tool described here is only an example, and it goes without saying that various modes can be adopted.

Next, radiation from the liquid sample held in a strip shape on the liquid-retaining member is absorbed by the stimulable phosphor member of the measurement device, and then appropriate excitation is applied to the stimulable phosphor member in which the radiation energy is stored. By irradiating light, the accumulated radiation energy can be continuously read out as stimulated luminescence. Therefore, by using the above method to continuously measure the radiation emitted from a sample that has been separated and developed in liquid chromatography and continuously flows out, the separated and developed sample can be analyzed. It is possible to continuously detect the radioactive substances inside, making it possible to separate and identify the radioactive substances with high precision.

In addition, the emission time of photostimulated light from the phosphor is instantaneous, and the measurement time of photostimulated light can be measured regardless of the radiation intensity of the sample, so when using a sheet-shaped radiation measurement device, After attaching the sample to the measuring tool and continuously accumulating radiation energy from the sample in the measuring tool, the reading operation can be performed within several tens of seconds, thereby reducing the measurement time.

In addition, by removing the sample attached to the radiation measuring device (separating the liquid retaining member and the stimulable phosphor member in a separate measuring device), the storage operation and readout operation can be completely separated. Since it is also possible to carry out the reading operation for a plurality of measuring instruments at once. In this respect as well, the time required for conventional measurement can be shortened and the measurement operation can be simplified.

Therefore, the operating rate of the measuring device can be increased and the number of measurements can be increased. Furthermore, this means that
This means that even when using a radioactive isotope with a short half-life and low radiation intensity, measurements can be made with high accuracy under the same conditions. Furthermore, according to the present invention, even if only one measuring device is used, by preparing one or more measuring tools, the measurement efficiency is equivalent to that of using multiple measuring devices at the same time in the conventional method. is obtained.

Furthermore, in the present invention, the operation of moving a sheet-like measuring device containing a stimulable phosphor, the operation of attaching a sample to the measuring device, and the operation of absorbing and accumulating radiation emitted from the sample in the measuring device are performed. It is also possible to automate the readout operation of the radiation energy stored in the measurement tool, thereby further improving the workability.

Furthermore, the measuring device used in the present invention does not require a conventional scintillator and is made of a sheet of plastic material or the like, so it is very easy to handle. Furthermore, for example, by making the measuring device a separate type, the liquid retaining member and the stimulable phosphor member can be separated after the operation of accumulating radiation energy in the measuring device or after use, and the stimulable phosphor member can be separated from the stimulable phosphor member. The stimulable phosphor member, which is one component of the measurement tool, can be used repeatedly by irradiating the member with appropriate light to erase the remaining stored energy. This makes it possible to reduce the cost required for measurement.

Further, if the above-mentioned measuring device is used in radiation measurement, unlike the conventional liquid scintillation method, no solvent is required. Therefore, there is no need to particularly select a solvent or prepare a sample as in a liquid scintillator. In the present invention, the quenching phenomenon as in the previous stage, especially the quenching phenomenon for fluorescence, does not occur. Therefore, there is no need to perform complicated extinction correction (determination of counting efficiency) for measuring the radioactivity of a sample, and the measurement operation is simplified in this respect as well.

Therefore, since there is no particular need to remove impurities contained in the sample, there is no need for conventional sample pretreatment, and a high degree of skill and care based on experience is required when preparing the sample. It's something you don't do. In this respect as well, radiation measurement of the sample can be easily performed.

Below, a sheet-shaped radiation measurement device suitably used in the radioactive substance detection method of the present invention will be described.

When a sheet-like radiation measurement device is an integrated type, it basically consists of a stimulable fluorescent member in the form of a phosphor layer containing a stimulable phosphor, and a protective layer provided on the phosphor layer. A liquid retaining member in the form of a liquid layer.

As mentioned above, the stimulable phosphor used in the present invention is a phosphor that exhibits stimulated luminescence when irradiated with excitation light after absorbing radiation, but from a practical point of view, the wavelength The phosphor is preferably a phosphor that exhibits stimulated luminescence in the wavelength range of 300 to 500 nm by excitation light in the range of 400 to 800 nm. Examples of such stimulable phosphors include those described in U.S. Pat. No. 3,859,527.
Phosphors expressed by composition formulas such as SrS:Ce, Sm, SrS:Eu, Sm, ThO ₂ :Er, and La ₂ O ₂ S:Eu, Sm, as described in JP-A-55-12142.
ZnS: Cu, Pb, BaO・xAl ₂ O ₃ : Eu [However, 0.8
≦x≦10], and M ²⁺ O・xSiO ₂ :A [however,
M ²⁺ is Mg, Ca, Sr, Zn, Cd, or Ba;
A is Ce, Tb, Eu, Tm, Pb, Tl, Bi, or
A phosphor represented by a composition formula such as Mn, and x is 0.5≦x≦2.5] (Ba _1-xy , Mg _x , Ca _y ) is described in JP-A-12143-1983. FX: aEu ²⁺ [However, X
is at least one of Cl and Br,
A phosphor represented by the composition formula: x and y are 0<x+y≦0.6 and xy≠0, and a is 10 ^-6 ≦a≦5×10 ^-2 JP-A-12144-1987 stated in the issue
LnOX: xA [However, Ln is La, Y, Gd, and
X is at least one of Cl and Br, A is at least one of Ce and Tb, and x is 0<x<0.1] Phosphor, (Ba _1-x , M〓 _x )FX: yA [where M〓 is Mg,
At least one of Ca, Sr, Zn, and Cd, X is at least one of Cl, Br, and I, A is Eu, Tb, Ce, Tm, Dy, Pr, Ho,
At least one of Nd, Yb, and Er, x is 0≦x≦0.6, and y is 0≦y≦0.2] JP-A-55-160078 M listed in the official bulletin
FX・xA: yLn [However, M〓 is Ba, Ca, Sr,
At least one of Mg, Zn, and Cd, A
are BeO, MgO, CaO, SrO, BaO, ZnO,
Al ₂ O ₃ , Y ₂ O ₃ , La ₂ O ₃ , In ₂ O ₃ , Sio ₂ , TiO ₂ ,
ZrO ₂ , GeO ₂ , SnO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , and
At least one of ThO ₂ , Ln is Eu, Tb,
Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Sm,
and at least one of Gd, X is Cl,
At least one of Br, and I,
x and y are respectively 5×10 ^-5 ≦x≦0.5 and 0<y≦0.2] A phosphor is described in JP-A-56-116777 (Ba _1- x _{, M〓} At least one kind, A is at least one kind of zirconium and scandium, and a, x, y, and z are each 0.5≦a≦
1.25, 0≦x≦1, ^{10 -6} ≦y≦2×10 ^-1 , and 0<z≦10 ^-2 ], described in JP-A-57-23673 (Ba _1-x , M〓 _x ) F ₂・aBaX ₂ :yEu, zB [however,
M〓 is beryllium, magnesium, calcium,
at least one of strontium, zinc, and cadmium;
10 ^-6 ≦y≦2×10 ^-1 and 0<z≦2×10 ^-1 ] A phosphor is described in JP-A-57-23675 (Ba _{1 -x} , M〓 _x )F ₂・aBaX ₂ :yEu, zA [However,
M〓 is beryllium, magnesium, calcium,
At least one of strontium, zinc, and cadmium, X is at least one of chlorine, bromine, and iodine, A is at least one of arsenic and silicon, and a, x, y, and z are each 0.5≦ a≦1.25, 0≦x≦1, 10 ^-6 ≦
y≦2×10 ⁻¹ and 0<z≦5×10 ⁻¹ ]
A phosphor represented by the composition formula M〓OX:xCe [where M〓 is Pr,
Nd, Pm, Sm, Tb, Dy, Ho, Er, Tm, Yb,
and Bi, X is one or both of Cl and Br, and x is 0<
x < 0.1] Ba _1-x M _x/2 L _x/2 FX:yEu ²⁺ described in Japanese Patent Application No. 1989-89875 filed by the applicant [however,
M represents at least one alkali metal selected from the group consisting of Li, Na, K, Rb, and Cs; L represents Sc, Y, La, Ce, Pr, Nd, Pm,
Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu,
represents at least one trivalent metal selected from the group consisting of Al, Ga, In, and Tl; X is Cl,
represents at least one kind of halogen selected from the group consisting of Br and In; and x is 10 ^-2 ≦
x≦0.5, y is 0<y≦0.1] BaFX xA:yEu ²⁺ [However, ,X is
is at least one halogen selected from the group consisting of Cl, Br, and I; A is a fired product of a tetrafluoroboric acid compound; and x is
10 ^-6 ≦x≦0.1, y is 0<y≦0.1] BaFX xA: yEu described in Japanese Patent Application No. 158048/1983 filed by the present applicant ²⁺ [However, X is
at least one halogen selected from the group consisting of Cl, Br, and I; A is a hexafluoro compound consisting of a monovalent or divalent metal salt of hexafluorosilicic acid, hexafluorotitanic acid, and hexafluorozirconic acid; and x is 10 ^-6 ≦x≦0.1, and y is 0<y≦0.1. BaFX xNaX′: aEu ²⁺ described in Application No. 166320/1989 [However,
X and X′ are each at least one of Cl, Br, and I, and x and a are 0<x≦2 and 0<a≦0.2, respectively]; M〓FX・xNaX′:yEu ²⁺ :[However,
M〓 is at least one alkaline earth metal selected from the group consisting of Ba, Sr, and Ca;
X and X' are each at least one halogen selected from the group consisting of Cl, Br, and I; A is V, Cr, Mn, Fe, Co, and Ni
at least one transition metal selected from;
and x is 0<x≦2, y is 0<y≦0.2, and z is 0<z≦10 ^-2 . M〓FX・aM〓X′・bM′〓X″ ₂・cM〓
X ₃・xA:yEu ²⁺ [However, M〓 is at least one kind of alkaline earth metal selected from the group consisting of Ba, Sr, and Ca; M〓 is Li, Na, K,
is at least one alkali metal selected from the group consisting of Rb and Cs; M′〓 is Be and Mg;
is at least one divalent metal selected from the group consisting of; M is at least one trivalent metal selected from the group consisting of Al, Ga, In, and Tl; A is a metal oxide; X is at least one halogen selected from the group consisting of Cl, Br, and I; X′, X″, and X are F, Cl,
at least one kind of halogen selected from the group consisting of Br and I; and a is 0≦a≦
2, b is 0≦b≦10 ^-2 , c is 0≦c≦10 ^-2 , and a+b+c≧10 ^-6 ; x is 0<x≦0.5, y
and 0<y≦0.2].

However, the photostimulable phosphor used in the radiation measurement device of the present invention is not limited to the above-mentioned phosphor, but is a fluorescent material that exhibits stimulated luminescence when irradiated with excitation light after absorbing radiation. It can be any body.

The phosphor layer can be formed, for example, by the following method. First, the above-mentioned stimulable phosphor particles and binder are added to a suitable solvent (for example, lower alcohol, chlorine atom-containing hydrocarbon, ketone, ester, ether), and the mixture is thoroughly mixed to form a binder solution. A coating solution in which the stimulable phosphor is uniformly dispersed is prepared.

Examples of binders include binders typified by proteins such as gelatin, synthetic polymeric substances such as polyvinyl acetate, nitrocellulose, polyurethane, polyvinyl alcohol, and cotton-like polyester.

The mixing ratio of the binder and the stimulable phosphor particles in the coating solution varies depending on the shape of the intended measurement tool, the type of phosphor particles, etc., but is usually 1:8 to 1:40 (weight ratio). selected from the range.

Note that the coating liquid contains a dispersant for improving the dispersibility of the phosphor particles in the coating liquid, and
Various additives such as a plasticizer may be mixed in order to improve the bonding force between the binder and the phosphor particles in the phosphor layer after formation.

A coating film containing the phosphor particles and a binder prepared as described above is uniformly applied onto a sheet such as a glass plate, a metal plate, or a plastic sheet to form a coating film. This coating operation can be carried out using conventional coating means such as a doctor blade, roll coater, knife coater, etc.

Then, the formed coating film is dried by gradually heating, and a phosphor layer made of a binder in which stimulable phosphor is dispersed is formed on the sheet. The thickness of this phosphor layer is generally 50 to 500 μm.

In the present invention, a transparent protective film for physically and chemically protecting the phosphor layer is provided on the surface of the phosphor layer obtained as described above on the side where the liquid-retaining layer is provided. You can leave it there. Examples of materials used for the transparent protective film include cellulose acetate, polymethyl methacrylate, polyethylene terephthalate, and polyethylene. The thickness of the transparent protective film is usually about 3 to 20 μm.

In addition, on the surface of the phosphor layer opposite to the liquid-retaining layer, for example, a plastic material such as cellulose acetate, polyester, or polyethylene terphthalate; a metal sheet such as aluminum foil; baryta paper, resin-coated paper, etc. A support made of, for example, may be provided. The support can be provided by directly forming the phosphor layer on the support, or by adhering to the phosphor layer using an adhesive or the like.

In addition, when reading out the measuring device from the support side, the support is preferably formed of a transparent plastic material from the viewpoint of light transmittance to excitation light and stimulation light. By providing a support on one side of the phosphor layer in this way, the mechanical strength of the measuring tool can be increased, and a measuring tool with improved durability can be obtained.

In addition, the phosphor layer does not necessarily have to be formed by dispersing the stimulable phosphor in a binder as described above, but can be formed, for example, by vacuum evaporating phosphor particles onto a support. You may.

Next, a liquid retaining layer is formed on one side of the phosphor layer (on the surface of the protective film if a protective film is provided thereon).

When a liquid sample is spotted on the liquid-retaining layer, the sample spreads laterally in proportion to the amount of spotting and also permeates in the depth direction, making it substantially uniform over the unit area of the liquid-retaining layer. It is desirable to be able to hold a large amount of sample. As a material for the liquid-retaining layer having such a function, for example, a porous structure that adsorbs and holds a liquid sample by a physical mechanism such as capillarity is used. Examples of porous structures include:
Fibrous materials such as paper such as filter paper and fabrics such as gauze; and non-fibrous materials such as porous polymers, porous glass or glass-like materials can be mentioned. In addition, it is also possible to use a substance that swells with the solvent of the sample solution and thereby absorbs the sample solution.

In addition, when the solvent is a hydrophilic solvent such as water, the materials for the liquid-retaining layer include natural polymer substances and their derivatives such as gelatin, agarose, and cellulose; synthetic homopolymers such as polyvinyl alcohol and polyacrylamide. , and synthetic polymeric substances such as synthetic copolymers obtained by copolymerizing a hydrophilic monomer having a hydrophilic group such as a hydroxyl group or a carboxyl group with a hydrophobic monomer. When the solvent is a lipophilic solvent, examples of materials for the liquid-retaining layer include synthetic polymeric substances such as nylon, polyethylene, and polyester in addition to the above-mentioned substances.

For example, the liquid retaining layer can be attached on the phosphor layer.
As a solution in water or other solvents,
Alternatively, it can be carried out by a known layer forming method such as coating the surface of the phosphor layer as a latex-like dispersion.

In order to prevent the adhered liquid sample from spreading laterally beyond a certain width, the liquid-retaining layer is provided with wires, lattices, or mesh-like grids made of a suitable plastic material, metal, etc. By doing so, a partition of an appropriate size and shape may be provided. Further, the liquid retaining layer may be a single layer or may be laminated as a plurality of layers. The thickness of the liquid-retentive layer can be suitably set depending on the type and amount of radioactive substance contained in the sample, the type of solvent, etc., but is preferably in the range of about 1 μm to 10 mm.

The liquid-retaining layer formed in this manner is desirably transparent from the viewpoint of light transmittance to excitation light and stimulation light when reading out the measuring device from the liquid-retaining layer side.

Note that various activation treatments may be performed on the surface of the phosphor layer (or protective film) in order to improve the adhesion with the liquid retaining layer. Examples of such surface activation treatments include chemical treatments using chemicals such as acids, alkalis, and etching solutions; physical treatments such as surface roughening treatments; electrical treatments such as corona discharge, high frequency discharge, glow discharge, and activated plasma. Treatment with light such as ultraviolet rays or laser; flame treatment; ozone oxidation treatment.

Furthermore, the side surfaces of the sheet-like measuring device thus obtained may be edged with a polymer coating material such as polyurethane or acrylic resin in order to increase the mechanical strength of the measuring device.

The sheet-shaped radiation measuring device used in the present invention can be made into any shape and size, such as square, circular, or oval, depending on the measurement conditions of the measuring device, the amount of sample, the intensity of radioactivity of the sample, etc. can.

In the present invention, the sheet-like radiometry device also includes a liquid-retaining member in the form of a liquid-retaining support medium for adsorbing and holding a liquid sample, and a liquid-retaining member for accumulating radiation energy from the sample and then emitting it as photostimulated light. The stimulable phosphor member may be in the form of a separate stimulable phosphor sheet.

In a separate type radiation measuring device set, the stimulable phosphor sheet is basically a phosphor sheet consisting of the support described above and a binder that contains and supports the stimulable phosphor in a dispersed state. It consists of body layers. Further, it is preferable that a protective film as described above be provided on the surface of the phosphor layer opposite to the support in order to physically and chemically protect the phosphor layer.

The liquid-retaining support medium, which is the other component of the separate measuring device set, can be formed from the same material as that used for the liquid-retaining layer as described above. This liquid retaining member may be provided with supporting aids such as a glass plate or a plastic sheet.

Next, regarding the method of detecting radioactive substances of the present invention using a sheet-like radiation measurement device containing a stimulable phosphor, please refer to the schematic diagrams shown in FIGS. 1 and 2 of the attached drawings. I will explain.

Figure 1 shows that in liquid chromatography,
FIG. 2 is a schematic explanatory diagram of a method for detecting radioactive substances contained in a continuously dropped liquid sample by using an integrated sheet-like radiation measurement device.

The sample to be measured in the present invention, ie, the liquid sample containing a radioactive substance, may be a solution or a suspension, and may be colored.

Furthermore, any type of radiation emitted from the radioactive substance in the sample can be measured, such as α rays, β rays, γ rays, proton rays, neutron rays, light rays, meson rays, and cosmic rays. That is, radiation from any radionuclide can be measured.

In the present invention, when the sheet-like radiation measuring device used is an integrated type, the radioactive substance detection operation is performed, for example, as follows.

First, in the sample adhesion section 2 of the integrated radiation measuring device 1, a liquid sample 4 is dropped onto the liquid-retaining layer of the measuring device 1 from the lower part of a column 3 filled with an adsorbent. The measuring tool 1 is moved in the directions of the arrows X and Y as described above while the liquid sample 4 is being dropped. Due to this movement, the sample adheres to the measuring tool 1 in a continuous or discontinuous band shape, and this sample is adsorbed and held in the liquid retaining layer of the measuring tool 1.

Next, in the radiation energy storage section 5, at least a portion of the radiation energy emitted from the radioactive substance in the sample held in the liquid-retaining layer of the measuring device 1 is absorbed by the phosphor layer of the measuring device 1. is accumulated. The accumulation time of this radiation energy is
Although it varies depending on the intensity of radiation emitted from the radioactive substance contained in the sample, the amount and concentration of the substance, the shape of the measuring device, the intensity of stimulated luminescence, etc., it usually takes about 1 second to 1 minute. Note that in the storage section 5, the sample on the measuring tool 1 may be dried by heating the measuring tool 1 at the same time.

Next, in the stored energy reading section 6, the measurement tool 1 is irradiated with excitation light 8 emitted from the light source 7. It is preferable that the beam diameter of this excitation light 8 has at least the width of the sample attachment site, that is, the width of the band formed by the attachment of the sample.
When the phosphor layer of the measuring device 1 is irradiated with excitation light, it emits stimulated luminescence with an amount of light proportional to the accumulated radiation energy, and this light enters a photodetector 9 such as a photomultiplier tube. As the photodetector 9, a filter is attached that transmits only light in the wavelength range of stimulated luminescence and cuts out light in the wavelength range of excitation light.
A device that is capable of detecting only stimulated luminescence is used. The stimulated luminescence detected by the photodetector 9 is converted into an electrical signal, which is amplified to an appropriate level electrical signal by the amplifier 10 and then input to the recording device 11.

In the recording device 11, the level of an electrical signal corresponding to the radiation dose absorbed by the measuring tool 1, for example, the count value of electrical pulses, is displayed as a digital value. Examples of the recording device 11 include one that scans a photosensitive measuring instrument with a laser beam or the like and records it optically, one that displays it electronically on a CRT or the like, or one that displays a radiation image displayed on a CRT or the like using a video printer or the like. Recording devices based on various principles can be used, such as those that record on a heat-sensitive recording and measuring device using a hot ray.

In addition, by providing a data processing circuit in the recording device 11, the radioactivity intensity can be calculated from the obtained digital value according to the readout efficiency (luminous efficiency of stimulated luminescence) and the accumulation time of radiation energy, which are input in advance. By calculating and further inputting the radiation intensity per molecule of the target radioactive substance, the amount or concentration of the radioactive substance per each attachment site of the sample (or the reading pixel of stimulated luminescence) is calculated. It is also possible to display and record the data.

In addition, in the integrated radiation measurement device, the liquid-retaining member and the stimulable phosphor member are separated before the readout operation, that is, the measuring device is obtained by removing the liquid-retaining layer (stimulable phosphor member). It is also possible to subject it to a read operation.

Figure 2 shows that in liquid chromatography,
FIG. 2 is a schematic explanatory diagram of a method for detecting radioactive substances contained in a liquid sample that is continuously dropped by using a separate sheet-like radiation measurement device set.

In the present invention, when the sheet-like radiation measurement device used is a separate type, the radioactive substance detection operation is performed, for example, as follows.

First, in the sample attachment part 22, the liquid-retaining support medium 2, which is one component of the radiation measuring instrument set, is
A liquid sample 24 is dropped onto the sample 1 from the bottom of a column 23 filled with an adsorbent. Liquid retaining support medium 2
1 is moved as described above in the directions of arrows X and Y while the liquid sample 24 is being dropped. As a result of this movement, the sample adheres to the liquid-retentive support medium 21 in a continuous or discontinuous band shape and is then adsorbed and retained.

Next, in the radiation energy storage section 26, the liquid-retaining support medium 21 holding the sample and the stimulable phosphor sheet 25 are superimposed so as to be in close contact with each other. In this overlapping state, at least a part of the radiation energy emitted from the radioactive substance in the sample held in the liquid-retaining support medium 21 is absorbed and accumulated in the stimulable phosphor sheet 25. .

Next, after separating the liquid-retaining support medium 21 and the stimulable phosphor sheet 25, the stimulable phosphor sheet 25 in which the radiation energy has been accumulated is
The light source 28 in the stored energy readout section 27
Excitation light 29 emitted from is irradiated. When irradiated with excitation light, the stimulable phosphor sheet 25 emits stimulated luminescence with an amount of light proportional to the accumulated radiation energy, which enters a photodetector 30 such as a photomultiplier tube. The stimulated luminescence detected by the photodetector 30 is converted into an electrical signal, and after being amplified to an appropriate level electrical signal in the amplifier 31,
It is input to the recording device 32.

Incidentally, in a separate type radiation measuring device set, it is also possible to perform the sample attachment operation and the readout operation with the liquid-retaining support medium and the stimulable phosphor sheet being superimposed.

In the present invention, the method for moving the measuring device during the operation of attaching the liquid sample continuously supplied from the adsorbent-filled column to the sheet-like radiation measuring device (or liquid-retentive support medium) is as described above. X,Y
The measurement tool is not limited to a reciprocating movement that combines movement in two directions; for example, the measuring tool may be rotated horizontally while slightly shifting its center position.
In this case, the sample is sucked and held in a spiral shape on the measuring tool.

In the present invention, it is of course possible to use methods other than those exemplified above as a method for reading the radiation energy of the sample accumulated in the radiation measuring device.

Furthermore, operations according to the radioactive substance detection method of the present invention are not limited to the above-mentioned operations; for example, based on the obtained data, samples are collected only from areas where radioactive substances have been detected, and It is also possible to efficiently separate radioactive substances. Furthermore, it is also possible to automate the entire measurement operation by, for example, continuously performing the operations of attaching a liquid sample to a radiation measuring device, accumulating radiation energy in the measuring device, and reading out the measuring device. .

After use, the radiation measurement device is cleaned with an appropriate solvent to remove the sample attached to the measurement device, and the energy remaining in the measurement device is erased by irradiation with light. By doing so, it can be reused and can be used particularly effectively for detecting radioactive substances as described above.
In particular, a separate radiation measuring instrument set is practically superior in that only the stimulable phosphor member can be used repeatedly.

The method for detecting radioactive substances in a liquid chromatograph of the present invention can be suitably used especially when continuously measuring a small amount of liquid sample, and can detect radioactive substances contained in the small amount of sample. can be detected quickly and with high precision. Then, it becomes possible to separate and identify radioactive substances contained in the separated and expanded liquid sample with high precision.

[Brief explanation of the drawing]

Figure 1 shows that in liquid chromatography,
This is a schematic explanatory diagram of a method for detecting radioactive substances contained in a continuously dropped liquid sample by using an integrated sheet-like radiation measurement device. 1: Radiation measurement device, 2: Sample attachment part, 3: Column filled with adsorbent, 4: Liquid sample,
Y: moving direction of measuring tool, 5: storage section, 6: reading section, 7: light source, 8: excitation light, 9: photodetector, 1
0: Amplifier, 11: Recording device. Figure 2 shows that in liquid chromatography,
This figure shows a schematic explanatory diagram of a method for detecting radioactive substances contained in a liquid sample that is continuously dropped by using a separate sheet-like radiation measuring device set. 21: liquid-retentive support medium, 22: sample attachment part,
23: column filled with adsorbent, 24: liquid sample, X, Y: moving direction of measuring tool, 25: stimulable phosphor sheet, 26: storage section, 27: readout section, 2
8: light source, 29: excitation light, 30: photodetector, 3
1: Amplifier, 32: Recording device.

Claims (1)

[Claims] 1 (1) A stimulable phosphor containing a stimulable phosphor and a stimulable phosphor under the column filled with an adsorbent so as to receive and retain a liquid sample passed through the column. By supplying a sheet-like radiation measuring device consisting of a liquid retaining member provided on the liquid sample and then sequentially moving the radiation measuring device in the plane direction of the sheet, the liquid sample is continuously or (2) A step of causing the stimulable phosphor member of the radiation measuring device to absorb at least a portion of the radiation energy emitted from the radioactive substance held in the radiation measuring device; (3) ) A step of continuously measuring the radioactivity in the sample by emitting the radiation energy stored in the radiation measuring device as photostimulated light and photoelectrically reading the stimulated light; A method for detecting radioactive substances in liquid samples using GRAPHIE. 2. The sheet-like radiation measuring device has a rectangular shape, and the movement of the radiation measuring device in the step (1) above includes reciprocating movement along one side of the rectangle and a direction perpendicular to the rectangular direction. 2. The method for detecting a radioactive substance according to claim 1, comprising alternating repetition with micro-movement. 3. The method for detecting a radioactive substance according to claim 1, wherein the liquid-retaining member comprises a porous structure. 4. The method for detecting a radioactive substance according to claim 1, wherein the stimulable phosphor member is made of a binder containing and supporting a stimulable phosphor in a dispersed state. 5. The method for detecting a radioactive substance according to any one of claims 1 to 4, wherein the stimulable phosphor is a divalent europium-activated alkaline earth metal fluorohalide phosphor. 6 (1) A liquid retaining member is supplied under the column filled with the adsorbent so as to receive and hold the liquid sample that has passed through the column, and the liquid retaining member is moved in the direction along the surface of the column. (2) attaching the liquid sample to the retentive member in a continuous or intermittently manner by sequentially moving the liquid sample to the retentive member; A step of causing the stimulable phosphor member to absorb at least a portion of the radiation energy emitted from the radioactive substance held in the liquid retaining member by overlapping; (3) accumulating in the stimulable phosphor member; a step of continuously measuring radioactivity in the sample by emitting radiation energy as photostimulated light and reading the stimulated light photoelectrically; A method for detecting radioactive substances in samples. 7 The liquid-retaining member has a rectangular sheet shape, and the movement of the liquid-retaining member in the step (1) above includes reciprocating movement along one side of the rectangle and a direction perpendicular thereto. 7. The method for detecting a radioactive substance according to claim 6, which comprises alternating repetition of micro-movement. 8. The method for detecting a radioactive substance according to claim 6, wherein the liquid-retaining member comprises a porous structure. 9. The method for detecting a radioactive substance according to claim 6, wherein the stimulable fluorescent member comprises a binder containing and supporting a stimulable phosphor in a dispersed state. 10. The method for detecting a radioactive substance according to any one of claims 6 to 9, wherein the stimulable phosphor is a divalent europium activated alkaline earth metal fluorohalide phosphor.