Analysis method and analysis apparatus

Abstract

To provide a method for efficiently analyzing a target substance even when a source solution contains a small-sized chemical species at a low concentration.SOLUTION: There is provided a method for analysis for estimating the concentration of a target substance in a source solution containing the target substance and a standard substance, the method including: a concentration step of concentrating the source solution to obtain a concentrated solution; and a concentration measurement step of measuring concentrations of the target substance and the standard substance in the concentrated solution. In the concentration step, the target substance and the standard substance are of the same chemical species, the standard substance includes an isotope ES of an element EA contained in the target substance, and the concentration CA,0 of the target substance in the source solution is estimated by the following equation (2) using the concentration CA,1 of the target substance in the concentrated solution, the concentration CS,0 of the standard substance in the source solution, the concentration CS,1 of the standard substance in the concentrated solution, the concentration ratio X of the source solution in the concentration step, and the recovery rate R of the standard substance determined by the following equation (1): R=CS,1 / (X×CS,0) (1): CA,0=CA,1 / (X×R) (2).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an analytical method comprising concentrating a stock solution containing an analyte and then determining the concentration of the analyte. [Background technology]

[0002] Various analyses are performed in areas such as measuring trace substances present in river water, seawater, rainwater, etc., water quality control for water used in factories, etc., and clinical testing of biological samples such as blood and urine. In these analyses, samples are often subjected to pretreatment such as separation, purification, and concentration to ensure the detection sensitivity of the target substances. Known examples of such pretreatments include solid phase extraction, precipitation, and membrane separation.

[0003] Of these, solid phase extraction and precipitation methods are capable of separating and concentrating the target substance in the original solution, but they have problems with reproducibility and tend to result in variations in the recovery rate of the target substance. Known membrane separation methods include those using an ultrafiltration membrane, a nanofiltration membrane, a reverse osmosis membrane, a forward osmosis membrane, and the like.

[0004] Ultrafiltration and nanofiltration membranes separate or concentrate by sieving based on molecular weight cutoff, which is generally on the order of several hundred to several thousand, making it difficult to separate or concentrate small chemical species, such as simple elements or ions, using ultrafiltration or nanofiltration membranes.

[0005] The reverse osmosis membrane and the forward osmosis membrane each have the property of allowing only water to pass through. In reverse osmosis, high pressure is applied to a raw solution placed on one side of a reverse osmosis membrane, causing only the water in the raw solution to pass through the reverse osmosis membrane, thereby concentrating the raw solution.In forward osmosis, the difference in osmotic pressure between the raw solution and the draw solution placed through the forward osmosis membrane is used as the driving force, causing only the water in the raw solution to move to the draw solution, thereby concentrating the raw solution. Thus, forward and reverse osmosis allow for the separation or concentration of small size species. For example, Patent Document 1 discloses a method for concentrating test water by reverse osmosis and then analyzing the metal ion concentration in the test water. Patent Document 2 discloses a method for concentrating test water by forward osmosis and then analyzing the metal ion concentration in the test water. Patent Document 3 discloses a method for concentrating a raw material solution containing an analyte at a concentration below the lower limit of quantitation by forward osmosis, thereby enabling quantitation. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-156692 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-092564 [Patent Document 3] International Publication No. 2023 / 033069 Summary of the Invention [Problem to be solved by the invention]

[0007] When the concentration of the analyte contained in the original solution is low, it is necessary to concentrate the original solution prior to measuring the concentration of the analyte. In this case, the concentrated original solution does not necessarily retain the entire amount of the analyte contained in the original solution. During the concentration process, the analyte is often partially lost, for example, by dissipation or decomposition.

[0008] Herein, the ratio of the weight of the analyte contained in the concentrated solution to the weight of the analyte contained in the original solution before concentration is referred to as the "recovery rate." In order to estimate the concentration of the analyte contained in the original solution by concentrating a dilute solution to obtain a concentrated solution and measuring the concentration of the analyte in the concentrated solution, it is necessary to estimate the "recovery rate" of the analyte in the concentration operation.

[0009] To estimate the recovery rate of an analyte, for example, an internal standard of known concentration is added to an original solution, and the concentration of the analyte and the internal standard are measured for the concentrated solution after concentration, and the recovery rate of this internal standard is used as the recovery rate of the analyte. However, because the internal standard generally uses a different chemical species that can be distinguished from the analyte in concentration measurements, the recovery rate of the internal standard does not necessarily coincide with the recovery rate of the analyte. Another method for estimating the recovery rate of an analyte is to prepare a standard solution containing the same chemical species as the analyte at a known concentration, and then measure the concentration of the solution after concentrating the standard solution to determine the recovery rate. This method has the advantage of providing an accurate value for the recovery rate of the analyte, but the disadvantage is that it is a time-consuming procedure.

[0010] An object of the present invention is to provide a method for efficiently concentrating and analyzing a target substance, even when the target substance is a small-sized chemical species and the original solution contains this at a low concentration. [Means for solving the problem]

[0011] The present invention, which solves the above problems, is as follows.

[0012] Aspect 1: An analytical method for estimating the concentration of an analyte in a stock solution containing the analyte, a standard, and a solvent, comprising: The analysis method includes a concentration step of concentrating the original solution to obtain a concentrated solution, and a concentration measurement step of measuring the concentrations of the analyte and the standard in the concentrated solution, The concentration step is carried out by forward osmosis or reverse osmosis, The target substance and the standard substance are the same chemical species, and the standard substance contains the element E A Isotope E of S Including, A measured concentration C of the analyte in the concentrated solution A,1, the concentration C of the standard in the stock solution S,0 , the measured concentration C of the standard in the concentrated solution S,1 The concentration ratio X of the original solution in the concentration step, and the recovery rate R of the standard substance in the concentration step calculated by the following formula (1) are used to calculate the concentration C of the analyte substance in the original solution by the following formula (2): A,0 Estimate the Analysis method. R=C S,1 / (X×C S,0 ) (1) C A,0 =C A,1 / (X×R) (2) <<Aspect 2>> The analytical method according to Aspect 1, further comprising an addition step, prior to the concentration step, of adding the standard substance to an analyte solution containing an analyte substance and a solvent to prepare the original solution. <Embodiment 3> The isotope E in the standard material S is a radioisotope, a storage step of storing the analyte solution before the adding step, The period of the storage step is S is more than 10 times the half-life of 3. The analytical method according to embodiment 2. Aspect 4: The element E in the target substance A is a radioisotope. Aspect 5: The element E A The half-life of the isotope E in the standard material is S 5. The method of claim 4, wherein the half-life of the antibody is longer than the half-life of the antibody. Aspect 6: The element E in the target substance A The half-life of the isotope E in the standard material is S 6. The method of claim 5, wherein the half-life of the antibody is 10 times or more. <Embodiment 7> Element E in the substance to be analyzed A The analytical method according to aspect 6, wherein the half-life of Aspect 8: The isotope E S The analytical method according to aspect 7, wherein the half-life of the Aspect 9: The isotope E S The analytical method according to any one of aspects 1 to 6, wherein the half-life of the compound is 1 day or more and less than 100 days. Aspect 10: The analytical method according to any one of Aspects 1 to 8, wherein the concentration step is carried out by forward osmosis using a forward osmosis membrane. Aspect 11: The analytical method according to aspect 10, wherein the forward osmosis membrane is a composite semipermeable membrane comprising a support layer and a separation active layer provided on the support layer, and the separation active layer comprises polyamide. Aspect 12: The analytical method according to any one of Aspects 1 to 7, wherein the concentrations of the target substance and the standard substance in the concentration measurement step are measured by one or more methods selected from the group consisting of chromatography, electromagnetic wave analysis, mass spectrometry, ion analysis, radioactivity analysis, electrochemical analysis, thermal analysis, and X-ray analysis. [Effects of the Invention]

[0013] According to the present invention, a method for efficiently concentrating and analyzing a target substance is provided, even when the target substance is a small-sized chemical species and the original solution contains the target substance at a low concentration. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a graph showing the relationship between the concentration ratio of I- ions and the concentration ratio based on the weight of the original solution in the concentration of an aqueous KI solution. [Figure 2] FIG. 2 is a graph showing the relationship between the concentration ratio of K + ions and the concentration ratio based on the weight of the original solution in the concentration of an aqueous KI solution. [Figure 3] FIG. 3 is a graph showing the relationship between the concentration ratio of I − ions and the volumetric concentration ratio of the original solution in the concentration of an aqueous KI solution. [Figure 4] FIG. 4 is a graph showing the relationship between the concentration ratio of K + ions and the volumetric concentration ratio of the original solution in the concentration of an aqueous KI solution. [Figure 5]FIG. 5 is a graph showing the relationship between the concentration ratio of I- ions and the concentration ratio based on the weight of the original solution when concentrating an aqueous NaI solution in the presence of KNO3. [Figure 6] FIG. 6 is a graph showing the relationship between the concentration ratio of Na+ ions and the concentration ratio based on the weight of the original solution when concentrating an aqueous NaI solution in the presence of KNO3. [Figure 7] FIG. 7 is a graph showing the relationship between the concentration ratio of I- ions and the concentration ratio based on the weight of the original solution in the concentration of an aqueous NaI solution at pH 2.0. [Figure 8] FIG. 8 is a graph showing the relationship between the concentration ratio of Na + ions and the concentration ratio based on the weight of the original solution when concentrating an aqueous NaI solution at pH 2.0. [Figure 9] FIG. 9 is a graph showing the effect of counter ions on the forward osmosis membrane concentration of an aqueous solution containing I- ions. [Figure 10] FIG. 10 is a graph showing the relationship between the concentration ratio of 131I in forward osmosis membrane concentration of distilled water and rainwater containing 131I and the concentration ratio based on the weight of the original solution. DETAILED DESCRIPTION OF THE INVENTION

[0015] The analytical method of the present invention comprises: 1. An analytical method for estimating the concentration of an analyte in a stock solution comprising the analyte, a standard, and a solvent, comprising: The analysis method includes a concentration step of concentrating the original solution to obtain a concentrated solution, and a concentration measurement step of measuring the concentrations of the analyte and the standard in the concentrated solution, The concentration step is carried out by forward osmosis or reverse osmosis, The target substance and the standard substance are the same chemical species, and the standard substance contains the element E A Isotope E of S Including, A measured concentration C of the analyte in the concentrated solution A,1 , the concentration C of the standard in the stock solution S,0 , the measured concentration C of the standard in the concentrated solutionS,1 The concentration ratio X of the original solution in the concentration step, and the recovery rate R of the standard substance in the concentration step calculated by the following formula (1) are used to calculate the concentration C of the analyte substance in the original solution by the following formula (2): A,0 Estimate the It is an analytical method. R=C S,1 / (X×C S,0 ) (1) C A,0 =C A,1 / (X×R) (2)

[0016] The analytical method of the present invention comprises: The method may further include an addition step of adding a standard substance to an analyte solution containing an analyte substance and a solvent to prepare the original solution, The method may include a storage step of storing the analyte solution before the adding step.

[0017] In the method of the present invention, the standard substance is a chemical species of the same kind as the target substance, and is an element E in the target substance. A Isotope E of S Use something that includes. Since the standard substance in the method of the present invention is the same chemical species as the analyte, the recovery rate of the standard substance can be considered to be the same as the recovery rate of the analyte. S Therefore, the standard substance of the present invention can be used as an internal standard substance. Therefore, in the present invention, the recovery rate of the analyte can be accurately estimated without the need to calculate the recovery rate of the analyte prior to concentration and concentration measurement, thereby enabling the concentration of the analyte in the original solution to be analyzed efficiently and accurately.

[0018] "Undiluted Solution" The original solution used in the analytical method of the present invention contains an analyte, a standard, and a solvent. First, the analyte and standard substances contained in the original solution will be described.

[0019] <<Substances to be analyzed and standard substances>> In the present invention, the analyte and the standard contained in the original solution are the same chemical species. In addition, the standard material is the element E in the target substance. A Isotope E of S Includes: That is, the standard material in the present invention is a reference material for a certain element E in the target substance. A and element E, which has the same number of protons but a different number of neutrons. S and is the same chemical species as the analyte. Isotope E in the standard material S may be a radioisotope. In addition, element E in the target substance A may be a radioisotope.

[0020] Element E in the standard material S , and element E in the analyte A In this case, the element E in the analyte A The half-life of isotope E in the standard material is S It is preferable that the half-life is longer than the half-life of the compound. Element E in the analyzed material A The half-life of the isotope E in the standard material is S The half-life may be 10 times or more, 15 times or more, 20 times or more, 50 times or more, 100 times or more, 500 times or more, 1,000 times or more, 5,000 times or more, 10,000 times or more, or 50,000 times or more of the half-life of the compound. Element E in the analyzed material A The half-life of isotope E in the standard material S If the isotope E is present in the original solution, it is more than 10 times the half-life of S Even if the original solution contains isotope E, if the original solution is stored for a specified period before analysis (described later), the isotope E in the original solution can be S Therefore, in this embodiment, the concentration of isotope E S The accuracy of the recovery estimate of the analyte can be ensured using a standard containing

[0021] For the above reasons, the isotope E in the standard material S The half-life of the compound is preferably relatively short, but from the viewpoint of ease of handling, it is preferable that the half-life has a certain length. From these perspectives, the isotope E in the standard material S The half-life of may be 1 day or more, 2 days or more, 3 days or more, 4 days or more, or 5 days or more, and may be less than 100 days, 75 days or less, 50 days or less, 30 days or less, 20 days or less, 15 days or less, or 10 days or less. Isotope E in the standard material S The half-life of may typically be greater than or equal to 1 day and less than 100 days.

[0022] On the other hand, element E in the target substance A The half-life of the compound is preferably long enough that the concentration does not substantially decrease even after the storage step described below. From this perspective, element E in the target substance A The half-life of may be, for example, 100 days or more, 1 year or more, 5 years or more, 10 years or more, 50 years or more, 100 years or more, 500 years or more, 1,000 years or more, or 1,500 years or more.

[0023] Element E with a half-life of 100 days or more A and isotope E whose half-life is more than 100 days but less than 100 days. S Examples of the combination include the combinations shown in the table below. [Table 1]

[0024] Element E in the analyzed material A , and isotope E in the standard material S may be one type or two or more types. The substance to be analyzed is element E A It contains iodine-129 as a standard isotope, E S It may contain iodine-131 as The analyte is the first element E AIodine-129 and the second element E as A and strontium 90 as the first isotope E S Iodine-131 as a second isotope, E S It may also contain strontium 82 as a sulphur atom.

[0025] The analyte and standard may be of any chemical species, so long as they are the same chemical species. The chemical species referred to here may be, for example, a monatom, a monatomic ion (including solvated ions and complex ions), a simple element, an ion consisting of only the same element (including solvated ions), an ion containing multiple elements (including solvated ions and complex ions), a molecule, or a clathrate compound.

[0026] <Concentration of the analyte and standard substance> The concentration of the analyte in the original solution may be below the detection limit of the intended concentration measurement, or may be so dilute that the measurement is considered unreliable, without going through a concentration step. From this perspective, the concentration of the analyte in the original solution may be, for example, 0.01 nmol / L (0.00001 μmol / L) or more and 10 μmol / L or less, or 0.001 μmol / L or more and 1 μmol / L or less.

[0027] The concentration of the standard in the stock solution may be similar to that of the analyte, but need not be excessively high as long as a reliable measurement can be obtained in the concentration measurement planned after the concentration step. From this perspective, the concentration of the standard in the original solution may be, for example, 0.01 nmol / L (0.00001 μmol / L) or more and 10 μmol / L or less, or 0.001 μmol / L or more and 1 μmol / L or less.

[0028] <Other ingredients> The stock solution in the present invention contains an analyte, a standard, and a solvent. The stock solution may contain other components other than the analyte, the standard, and the solvent. Other components contained in the original solution may be, for example, various compounds, salts, microorganisms, components in living organisms (red blood cells, white blood cells, antibodies, etc.), and the like.

[0029] <solvent> The solvent of the original solution in the present invention may contain one or more selected from water and organic solvents. The solvent of the original solution may be water or a mixture of water and a water-soluble organic solvent, and is typically water.

[0030] 《Storage process》 The analytical method of the present invention includes a concentration step and a concentration measurement step. The method may further include an addition step of adding a standard substance to an analyte solution containing an analyte substance and a solvent to prepare the original solution, The method may include a storage step of storing the analyte solution before the adding step. The storage step, addition step, concentration step, and concentration measurement step will be described below in this order.

[0031] The storage process involves the storage of the isotope E in the standard material. S is a radioisotope. This storage step may be carried out by storing the solution to be analyzed for a predetermined period of time. The storage mode may be appropriately determined by those skilled in the art depending on the properties of the solution to be analyzed, and may be, for example, storage at rest, under stirring, under shaking, etc. The storage temperature may also be appropriately determined by those skilled in the art depending on the properties of the solution to be analyzed. The solution to be analyzed may be, for example, a sample collected from the environment such as river water, seawater, or rainwater; water used in a factory; factory wastewater; a biological sample; etc., and therefore may contain components other than the substance to be analyzed and the solvent.

[0032] The storage process involves adding the isotope E S When the isotope E in the analyte solution is contained, S By reducing the concentration of isotope ES This is done to improve the accuracy of the estimation of the recovery of the analyte by using a standard containing The storage process is carried out for the isotope E S It is preferable that the half-life is 10 times or more. The solution to be analyzed is S When stored for 10 times the half-life of S The concentration of isotope E in the solution to be analyzed can be reduced to 1 / 2 the 10th power of the initial concentration, or about 0.1% of the initial concentration. S If the concentration of isotope E in the analyte solution is low to this extent, S Since the influence of the standard is substantially eliminated, the accuracy of the estimation of the recovery rate of the analyte by using the standard is guaranteed. The duration of the storage step does not need to be excessively long, e.g., for isotope E S The half-life may be 50 times or less, 20 times or less, or 15 times or less of the half-life of the compound.

[0033] 《Addition process》 After the above-mentioned storage step and before the concentration step described below, an addition step may be carried out in which a standard substance is added to an analyte solution containing an analyte substance and a solvent. The amount of standard substance added to the solution to be analyzed is desirably an amount that allows the concentration of the standard substance in the separation solution after addition to be known and that allows a highly reliable measurement value to be obtained in the concentration measurement step after the concentration step. Guidelines for the concentration of the standard in the aliquot solution after addition are given above.

[0034] 《Concentration process》 In the concentration step in the analytical method of the present invention, the raw solution is concentrated to obtain a concentrated solution. This concentration step is carried out by forward osmosis or reverse osmosis. Forward osmosis and reverse osmosis are capable of separating or concentrating small chemical species (eg, elemental elements, ions, etc.) without requiring heating of the original solution. Of these, the reverse osmosis method requires pressurizing the raw solution, and therefore requires an apparatus for this purpose. In contrast, forward osmosis does not require pressurization of the raw solution, except for the pressurization required for liquid transport, and is therefore preferable from the standpoints that it can be applied to unstable target substances for analysis and that it has the advantage of allowing the overall system to be made smaller. Therefore, the concentration step in the analytical method of the present invention is preferably carried out by forward osmosis using a forward osmosis membrane.

[0035] <Forward osmosis membrane> The forward osmosis membrane may be a composite semipermeable membrane comprising a support layer and a separating active layer provided on the support layer. The forward osmosis membrane is preferably modularized and used in the form of a forward osmosis membrane module. The forward osmosis membrane is preferably in the form of a hollow fiber, since this allows the membrane area per module of the forward osmosis membrane module to be increased. Therefore, the forward osmosis membrane used in the concentration step of the present invention is preferably a hollow fiber composite semipermeable membrane comprising a hollow fiber support layer and a separating active layer provided on one or both sides of the support layer.

[0036] (Support layer) The support layer of the forward osmosis membrane is a membrane for supporting the separation active layer. The support layer itself preferably does not exhibit substantial separation performance. The support layer preferably has micropores on its surface, the pore size of which is preferably 0.001 μm or more and 0.1 μm or less, more preferably 0.005 μm or more and 0.05 μm or less. The structure of the support layer other than the surface is preferably as sparse as possible while maintaining strength in order to reduce the permeation resistance of the permeating fluid. The sparse structure in this area is preferably, for example, a net-like structure, a structure having finger-like voids, or a mixed structure thereof.

[0037] The material of the support layer is preferably one that is not chemically damaged by the monomer solution, raw solution, and the induction solution described below when forming the separation active layer, and that can be molded into a microporous hollow fiber shape. From this perspective, the material of the support layer is, for example, Preferably, the polymer contains, as a main component, one or more selected from polyethersulfone, polysulfone, polyketone, polyetheretherketone, polyphenylene ether, polyvinylidene fluoride, polyacrylonitrile, polyimine, polyimide, polybenzoxazole, polybenzimidazole, and polyamide; More preferably, the main component is one or more selected from polyethersulfone, polysulfone, polyketone, and polybenzimidazole, More preferably, the main component is one or more selected from polysulfone and polyethersulfone, Polysulfone is particularly preferred. In the above, the term "main component" refers to the component that accounts for the largest weight ratio in the entire support layer, and in one embodiment, is a component that accounts for more than 50% by weight of the entire support layer.

[0038] When the support layer is in the form of hollow fibers, the diameter of the hollow fibers is not particularly limited. However, in consideration of film formation stability, ease of handling, and increasing the film area when made into a module, an outer diameter of 100 μm to 3,000 μm and an inner diameter of 30 μm to 2,500 μm is preferred, and an outer diameter of 200 μm to 1,500 μm and an inner diameter of 50 μm to 1,000 μm is more preferred.

[0039] Such a support layer may be produced by, for example, a known dry / wet film-forming method, melt film-forming method, wet film-forming method, or the like.

[0040] <Separation active layer> The separating active layer of the forward osmosis membrane of the present invention comprises a polyamide. The separating active layer may be provided on one or both surfaces of the support layer. When the forward osmosis membrane is in the form of a hollow fiber, the separating active layer may be provided on the inner surface of the hollow fiber support layer to avoid physical damage to the separating active layer. The thickness of the separating active layer of the forward osmosis membrane of the present invention is preferably as thin as possible to prevent pinholes, but is desirably an appropriate thickness to maintain mechanical strength and chemical resistance. From this viewpoint, the thickness of the separating active layer is preferably 0.1 μm to 3 μm, and more preferably 0.2 μm to 2 μm.

[0041] The separating active layer is preferably made of polyamide. The separating active layer made of polyamide is preferably made of a polycondensation product of one or more first monomers selected from the group consisting of polyfunctional amines and one or more second monomers selected from the group consisting of polyfunctional acid halides.

[0042] Examples of polyfunctional amines include polyfunctional aromatic amines, polyfunctional aliphatic amines, monomers having a plurality of reactive amino groups, and prepolymers thereof.

[0043] Polyfunctional aromatic amines are aromatic amino compounds having two or more amino groups in one molecule, and specific examples include m-phenylenediamine, p-phenylenediamine, etc. 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylamine, 3, 3'-Diaminodiphenyl ether, 4,4'-Diaminodiphenyl ether, 3,3' Examples of the diaminodiphenylamine include 4,4'-diaminodiphenylamine, 3,5-diaminobenzoic acid, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 3,4-diaminodiphenyl sulfone, 1,3,5-triaminobenzene, and 1,5-diaminonaphthalene, and these can be used alone or in combination. In particular, one or two members selected from m-phenylenediamine and p-phenylenediamine are preferably used.

[0044] The polyfunctional aliphatic amine is an aliphatic amino compound having two or more amino groups in one molecule, and specifically, for example, Primary amines having a cyclohexane ring, such as 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, 4,4'-bis(paraaminocyclohexyl)methane, 1,3-bis-(aminomethyl)cyclohexane, 2,4-bis-(aminomethyl)cyclohexane, and 1,3,5-triaminocyclohexane; Secondary amines with a piperazine ring, such as piperazine, 2-methylpiperazine, ethylpiperazine, and 2,5-dimethylpiperazine; Secondary amines having a piperidine ring, such as 1,3-bis(4-piperidyl)methane, 1,3-bis(4-piperidyl)propane, and 4,4'-bipiperidine; Amines with both primary and secondary amino groups, such as 4-(aminomethyl)piperidine: Other examples include ethylenediamine, propylenediamine, 1,2-propanediamine, 1,2-diamino-2-methylpropane, 2,2'-dimethyl-1,3-propanediamine, tris(2-aminoethyl)amine, N,N'-dimethylethylenediamine, N,N'-dimethylpropanediamine, etc., and these can be used alone or in mixtures. Mixtures of these polyfunctional aliphatic amines with the above-mentioned polyfunctional aromatic amines may also be used.

[0045] Examples of the monomer having a plurality of reactive amino groups include polyethyleneimine, amine-modified polyepichlorohydrin, and aminated polystyrene. As the prepolymer, for example, a prepolymer made of one or more selected from piperazine, 4-(aminomethyl)piperidine, ethylenediamine, and 1,2-diamino-2-methylpropane is preferably used.

[0046] Examples of polyfunctional acid halides include polyfunctional aromatic acid halides, polyfunctional aliphatic acid halides, etc. These may be bifunctional or higher so as to react with polyfunctional amines to form polymers.

[0047] The polyfunctional aromatic acid halide is an aromatic acid halide compound having two or more acid halide groups in one molecule.Specific examples include trimesic acid halide, trimellitic acid halide, isophthalic acid halide, terephthalic acid halide, pyromellitic acid halide, benzophenonetetracarboxylic acid halide, biphenyldicarboxylic acid halide, naphthalenedicarboxylic acid halide, pyridinedicarboxylic acid halide, benzenedisulfonic acid halide, etc., and these can be used alone or in combination.In particular, trimesic acid chloride alone, a mixture of trimesic acid chloride and isophthalic acid chloride, or a mixture of trimesic acid chloride and terephthalic acid chloride is preferably used.

[0048] The polyfunctional aliphatic acid halide is an aliphatic acid halide compound having two or more acid halide groups in one molecule.Specific examples include alicyclic polyfunctional acid halide compounds such as cyclobutanedicarboxylic acid halide, cyclopentanedicarboxylic acid halide, cyclopentanetricarboxylic acid halide, cyclopentanetetracarboxylic acid halide, cyclohexanedicarboxylic acid halide, and cyclohexanetricarboxylic acid halide; as well as propanetricarboxylic acid halide, butanetricarboxylic acid halide, pentanetricarboxylic acid halide, succinic acid halide, and glutaric acid halide.These can be used alone or in combination, and mixtures of these polyfunctional aliphatic acid halides with the above-mentioned polyfunctional aromatic acid halides can also be used.

[0049] The first and second monomers as described above may be dissolved in an appropriate solvent to prepare solutions, which may then be subjected to interfacial polymerization. The solvent for the first monomer is preferably, for example, water or alcohol, or a mixture thereof. Examples of the solvent for the second monomer include hydrocarbon solvents such as n-hexane, cyclohexane, n-heptane, n-octane, n-nonane, and n-decane, and these are preferably used alone or in mixture.

[0050] The interfacial polymerization for forming the separation active layer may be carried out in accordance with a known method. For example, by passing a solution of a first monomer through the inside of a hollow fiber support layer and then passing a solution of a second monomer through the inside of the hollow fiber support layer, or by passing a solution of a second monomer through the inside of the hollow fiber support layer and then passing a solution of a first monomer through the inside of the hollow fiber support layer, interfacial polymerization of the first monomer and the second monomer occurs on the inner surface of the hollow fiber support layer, and a separation active layer can be formed. After the first monomer solution is passed through, the pressure outside the hollow fiber support layer may be reduced and this reduced pressure state may be maintained for a certain period of time. After the interfacial polymerization, the formed separation active layer may be subjected to a heat treatment at about 100 to 150°C.

[0051] In the present invention, it is preferable to produce a hollow fiber support layer module by storing multiple hollow fiber support layers in a suitable housing, and in the state of this support layer module, to carry out interfacial polymerization of the first monomer and the second monomer to form a separating active layer on the inner surface of the support layer to form a hollow fiber forward osmosis membrane module, and then to carry out the concentration step using this hollow fiber forward osmosis membrane module.

[0052] <Inducing liquid> In the forward osmosis method using a forward osmosis membrane, a stock solution is passed through one side of the above-mentioned forward osmosis membrane (preferably the side on which the separating active layer is formed) and a draw solution is passed through the other side, and the difference in osmotic pressure between the two is used as a driving force to move the solvent from the stock solution to the draw solution through the forward osmosis membrane, thereby concentrating the stock solution.

[0053] The draw solution is a liquid that has a higher osmotic pressure than the original solution and has the function of displacing the solvent from the original solution. The inducer solution may be, for example, a solution containing a high concentration of inducer. Examples of the inducer include alkali metal salts, alkaline earth metal salts, ammonium salts, Examples include sugars, monoalcohols, glycols, and water-soluble polymers.

[0054] Specific examples of these include: Alkali metal salts include, for example, sodium chloride, potassium chloride, sodium sulfate, sodium thiosulfate, and sodium sulfite; Alkaline earth metal salts include, for example, magnesium chloride, calcium chloride, magnesium sulfate, etc.; Ammonium salts include, for example, ammonium chloride, ammonium sulfate, and ammonium carbonate; Examples of sugars include common sugars such as sucrose, fructose, and glucose, as well as special sugars such as oligosaccharides and rare sugars; Monoalcohols such as methanol, ethanol, 1-propanol, and 2-propanol; Glycols include, for example, ethylene glycol and propylene glycol; Examples of water-soluble polymers include polyethylene oxide, polypropylene oxide, and copolymers of ethylene oxide and propylene oxide. Each of them can be mentioned.

[0055] The concentration of the inducer in the inducer solution is preferably such that the osmotic pressure of the inducer solution is sufficiently higher than that of the stock solution, and the inducer solution can exert its function of displacing the solvent from the stock solution. For example, when an alkali metal salt or alkaline earth metal salt is used as the inducer, the concentration thereof may be, for example, 10% by weight or more and the saturated concentration or less. The solvent of the draw liquid may contain one or more selected from water and organic solvents. The solvent of the draw liquid may be water or a mixture of water and a water-soluble organic solvent, and is typically water.

[0056] <Concentration method> As described above, in the forward osmosis method using a forward osmosis membrane, a stock solution is passed through one side of the above-mentioned forward osmosis membrane (preferably the side on which the separating active layer is formed) and a draw solution is passed through the other side, and the difference in osmotic pressure between the two is used as a driving force to move the solvent from the stock solution to the draw solution through the forward osmosis membrane, thereby concentrating the stock solution.

[0057] The flow direction of the raw solution and the draw solution may be either parallel or countercurrent. The stock solution and the draw solution may be passed over the forward osmosis membrane in a circulation system in which they are each passed over the forward osmosis membrane and then supplied again to the forward osmosis membrane. for example, A concentration system is constructed having a forward osmosis membrane module, a raw solution tank, a draw solution tank, and piping connecting these. The raw solution is supplied from the raw solution tank to the forward osmosis membrane module, and the raw solution after passing through the forward osmosis membrane module is returned to the raw solution tank. The draw solution is supplied from the draw solution tank to the forward osmosis membrane module, and the draw solution after passing through the forward osmosis membrane module is returned to the draw solution tank. The circulation system is a preferred embodiment of the present invention.

[0058] The temperature during concentration is arbitrary, and may be, for example, 0° C. or higher and 50° C. or lower, with room temperature being sufficient. The concentration time may be any time until the concentration of the analyte in the original solution reaches a level at which a reliable measurement can be obtained in the intended concentration measurement.

[0059] 《Concentration measurement process》 In the concentration measurement step, the concentrations of the analyte and the standard in the concentrated solution obtained in the concentration step are measured. This concentration measurement allows the concentration of the analyte and the standard to be determined with high reliability, and the element E A and isotope E S Preferably, this is done by a method that can distinguish between the analyte and the standard by the difference in Such a method may be carried out by, for example, one or more methods selected from the group consisting of various types of chromatography, electromagnetic wave analysis based on light absorption, mass spectrometry, trace metal ion analysis, radioactivity analysis, electrochemical analysis, thermal analysis, and various types of X-ray analysis.

[0060] In a preferred embodiment of the present invention, the concentration may be measured by, for example, providing a branch pipe in the discharge pipe from the hollow fiber forward osmosis membrane module after the concentration step, and directly sending a portion of the concentrated solution concentrated to the desired concentration to the measuring device.

[0061] <<Method for estimating the concentration of the analyte in the original solution>> In the analytical method of the present invention, the measured value C of the concentration of the analyte in the concentrated solution is A,1 , the concentration of the standard in the stock solution C S,0 , the measured concentration of the standard in concentrated solution C S,1 The concentration ratio X of the original solution in the concentration step, and the recovery rate R of the standard substance in the concentration step calculated by the following formula (1) are used to calculate the concentration C of the analyte in the original solution by the following formula (2). A,0 Estimate. R=C S,1 / (X×C S,0 ) (1) C A,0 =C A,1 / (X×R) (2)

[0062] In the present invention, the standard is the same chemical species as the analyte, so the recovery rate of the standard is substantially the same as the recovery rate of the analyte. S It can be distinguished from the analyte by the presence of According to the method of the present invention, which uses such a standard substance as an internal standard substance, it is possible to accurately estimate the recovery rate of the analyte without the need to calculate the recovery rate of the analyte prior to concentration and concentration measurement, thereby enabling efficient and accurate analysis of the concentration of the analyte in the original solution. [Example]

[0063] In the following reference example, assuming that iodine atoms are used as the isotope element, the concentration behavior on a weight basis and a volume basis in forward osmosis concentration using a potassium iodide aqueous solution as the starting solution, as well as the effects of salt (potassium nitrate) and pH in forward osmosis concentration using a sodium iodide aqueous solution as the starting solution, were investigated.

[0064] <Manufacturing of forward osmosis membrane modules> A uniform hollow fiber spinning solution was prepared consisting of 19 mass% polysulfone (Udel-P3500, manufactured by Solvay Specialty polymers), 61 mass% N-methyl-2-pyrrolidone (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 20 mass% tetraethylene glycol (manufactured by Tokyo Chemical Industry Co., Ltd.). The above-mentioned stock solution was filled into a wet hollow fiber spinning machine equipped with a double spinneret. The stock solution at 40°C and an internal coagulation liquid (water) at 25°C were extruded from the double spinneret. The extruded material was run for 250 mm in air temperature-controlled at 30°C and a relative humidity of 98%, then coagulated in a coagulation bath (external coagulation liquid) filled with 30°C water. The material was then wound up at a tension of 30 g using a free roll as a turn roll to obtain a hollow fiber. The outer diameter of the obtained hollow fiber was 1.02 mm, and the inner diameter was 0.62 mm. This hollow fiber was used as a microporous hollow fiber support layer.

[0065] The microporous hollow fiber support layer was cut to a length of 120 mm, and a hollow fiber bundle of 130 fibers was formed. This hollow fiber bundle was housed in a cylindrical housing 20 mm in diameter and 100 mm in length, and both ends were fixed with an adhesive. Then, both outer ends of the adhesive-fixed parts were cut to open both ends of the hollow fiber bundle, thereby producing a microporous hollow fiber support layer module with an effective length of 80 mm.

[0066] An aqueous solution (first solution) containing 2.0 wt% m-phenylenediamine and 0.15 wt% sodium lauryl sulfate was passed through the hollow fibers of the resulting microporous hollow fiber support layer module for 20 minutes. After passing the solution, the first solution was removed from the module, and while the inner surfaces of the hollow fibers were wet with the first solution, the space outside the hollow fibers of the microporous hollow fiber support layer module was reduced in pressure to 90 kPaG and maintained at this reduced pressure for 1 minute. Air was then passed through the hollow fibers at a linear velocity of 210 cm / sec for 1 minute to remove excess first solution.

[0067] Next, an n-hexane solution (second solution) containing 0.20 wt % of 1,3,5-trimesoyl chloride was passed through the inside of the hollow fibers of the microporous hollow fiber support layer module for 2 minutes to cause interfacial polymerization between the m-phenylenediamine contained in the first solution and the 1,3,5-trimesoyl chloride contained in the second solution, thereby forming a separating active layer made of polyamide on the inside of the hollow fibers.

[0068] Thereafter, nitrogen was passed through the inside of the hollow fibers to remove excess second solution, and hot water at 85°C was passed through the inside of the hollow fibers at a linear speed of 5 cm / sec for 30 minutes. The entire module was then placed in an autoclave (manufactured by Tomy Seiko Co., Ltd., product name "SX-500") and high-temperature steam at 121°C was supplied for 20 minutes. Furthermore, both sides of the hollow fibers were washed with running water at 20°C for 30 minutes to produce a forward osmosis membrane module.

[0069] (1) Gravity-based concentration behavior in forward osmosis concentration using potassium iodide aqueous solution as the starting solution As the raw material liquid, 200 mL of potassium iodide (KI) aqueous solutions with concentrations of 0.08 mmol / L, 0.16 mmol / L, 0.24 mmol / L, 0.32 mmol / L, and 0.80 mmol / L were used. As the induction liquid, 250 mL of a magnesium chloride solution with a concentration of 1.0 mol / L was used. The feed solution was supplied to the inside of the hollow fibers of the forward osmosis membrane module, and the draw solution was supplied to the outside of the hollow fibers at a flow rate of 60 mL / min in parallel. After passing through the forward osmosis membrane module, the feed solution and draw solution were returned to the feed solution tank and draw solution tank, respectively, and concentration operation was performed by forward osmosis using a circulation system. Note that the feed solution with a concentration of 0.24 mmol / L was concentrated three times. The weight of the raw material liquid was measured at predetermined time intervals (5 minutes), and the value obtained by dividing the initial weight of the raw material liquid by the measured weight was used as the weight-based concentration factor at that time point. In addition, the raw material liquid was sampled every predetermined time (5 minutes), K +The following was measured using a microwave plasma atomic emission spectrometer (Agilent Technologies, model 4210MP-AES): I - The following was analyzed by ion chromatography (Tosoh Technosystems Co., Ltd., model "IC-2010"): The ion concentration was measured for each.

[0070] The results are shown in Tables 1-1 to 1-7 and FIGS.

[0071] [Table 2]

[0072] [Table 3]

[0073] [Table 4]

[0074] [Table 5]

[0075] [Table 6]

[0076] [Table 7]

[0077] [Table 8]

[0078] (2) Volumetric concentration behavior in forward osmosis using potassium iodide aqueous solution as the starting solution Concentration operations were carried out by forward osmosis in the same manner as described above in "(1) Weight-based concentration behavior in forward osmosis concentration using potassium iodide aqueous solution as the stock solution," except that 200 mL of each of potassium iodide (KI) aqueous solutions with concentrations of 0.04 mmol / L, 0.16 mmol / L, 0.24 mmol / L, and 0.32 mmol / L was used as the stock solution. Note that the concentration operations were repeated twice for the 0.04 mmol / L stock solution, and three times for the 0.24 mmol / L stock solution. The volume of the raw material liquid was measured at predetermined time intervals, and the value obtained by dividing the initial volume of the raw material liquid by the measured volume was used as the volume-based concentration factor at that time point. The results are shown in Tables 2-1 to 2-5 and FIGS.

[0079] [Table 9]

[0080] [Table 10]

[0081] [Table 11]

[0082] [Table 12]

[0083] [Table 13]

[0084] (3) Effect of salt (potassium nitrate) on forward osmosis concentration using sodium iodide aqueous solution as the starting solution The raw material solutions used were a 200 mL solution of a 5.0 mmol / L aqueous sodium iodide (NaI) solution without added potassium nitrate (KNO3) (KNO3 concentration 0 mmol / L), and solutions with added KNO3 at 2.5 mmol / L, 5.0 mmol / L, 10 mmol / L, 50 mmol / L, and 100 mmol / L. As the induction liquid, 250 mL of a magnesium chloride solution with a concentration of 1.0 mol / L was used. The feed solution was supplied to the inside of the hollow fibers of the forward osmosis membrane module, and the draw solution was supplied to the outside of the hollow fibers at a flow rate of 60 mL / min in parallel. After passing through the forward osmosis membrane module, the feed solution and the draw solution were returned to the feed solution tank and the draw solution tank, respectively, and concentration was performed by forward osmosis in a circulation system. The weight of the raw material liquid was measured at predetermined time intervals (5 minutes), and the value obtained by dividing the initial weight of the raw material liquid by the measured weight was used as the weight-based concentration factor at that time point. In addition, the raw material liquid was sampled every predetermined time (5 minutes), Na + The following was measured using a microwave plasma atomic emission spectrometer (Agilent Technologies, model 4210MP-AES): I - The following was analyzed by ion chromatography (Tosoh Technosystems Co., Ltd., model "IC-2010"): The ion concentration was measured for each.

[0085] The results are shown in Tables 3-1 to 3-6 and FIGS.

[0086] [Table 14]

[0087] [Table 15]

[0088] [Table 16]

[0089] [Table 17]

[0090] [Table 18]

[0091] [Table 19]

[0092] (4) Effect of pH on forward osmosis concentration using sodium iodide aqueous solution as the starting solution As the raw material liquids, 100 mL of each of the following nine aqueous solutions was used. An aqueous solution (pH 5.5) containing sodium iodide (NaI) at a concentration of 5.0 mmol / L and potassium nitrate (KNO3) at a concentration of 20 mmol / L. Aqueous solutions obtained by adding 1.0 mol / L hydrochloric acid to the above pH 5.5 aqueous solution to adjust the pH to 2.0, 2.5, 3.0, and 3.7, respectively; and Aqueous solutions obtained by adding 1.0 mol / L of sodium hydroxide solution to the above pH 5.5 aqueous solution to adjust the pH to 9.2, 10.0, 10.5, and 11.0, respectively. As the induction liquid, 250 mL of a magnesium chloride solution with a concentration of 1.0 mol / L was used. The feed solution was supplied to the inside of the hollow fibers of the forward osmosis membrane module, and the draw solution was supplied to the outside of the hollow fibers at a flow rate of 60 mL / min in parallel. After passing through the forward osmosis membrane module, the feed solution and draw solution were returned to the feed solution tank and draw solution tank, respectively, and a concentration operation was performed by forward osmosis using a circulation system. The concentration operation was repeated three times for each aqueous solution. The weight of the raw material liquid was measured at predetermined time intervals (5 minutes), and the value obtained by dividing the initial weight of the raw material liquid by the measured weight was used as the weight-based concentration factor at that time point. In addition, the raw material liquid was sampled every predetermined time (5 minutes), Na+ The following was measured using a microwave plasma atomic emission spectrometer (Agilent Technologies, model 4210MP-AES): I - The following was analyzed by ion chromatography (Tosoh Technosystems Co., Ltd., model "IC-2010"): The ion concentration was measured for each.

[0093] The results are shown in Tables 4-1 to 4-27 and FIGS.

[0094] [Table 20]

[0095] [Table 21]

[0096] [Table 22]

[0097] [Table 23]

[0098] [Table 24]

[0099] [Table 25]

[0100] [Table 26]

[0101] [Table 27]

[0102] Table 28

[0103] Table 29

[0104]

Table 30

[0105] Table 31

[0106] Table 32

[0107]

Table 33

[0108] Table 34

[0109] Table 35

[0110] Table 36

[0111] Table 37

[0112] [Table 38]

[0113] [Table 39]

[0114] [Table 40]

[0115] [Table 41]

[0116] [Table 42]

[0117] [Table 43]

[0118] [Table 44]

[0119] [Table 45]

[0120] [Table 46]

[0121] (5)I - Effect of counterions on forward osmosis membrane concentration of ion-containing aqueous solutions As the stock solutions, 200 g of each of the following two aqueous solutions was used. An aqueous solution containing sodium iodide (NaI) at a concentration of 5.0 mmol / L, and An aqueous solution containing potassium iodide (KI) at a concentration of 5.0 mmol / L. As the induction liquid, 200 mL of a magnesium chloride solution with a concentration of 1.0 mol / L was used. The feed solution was supplied to the inside of the hollow fibers of the forward osmosis membrane module, and the draw solution was supplied to the outside of the hollow fibers at a flow rate of 60 mL / min in parallel. After passing through the forward osmosis membrane module, the feed solution and the draw solution were returned to the feed solution tank and the draw solution tank, respectively, and concentration was performed by forward osmosis in a circulation system. The weight of the raw material liquid was measured at predetermined time intervals (10 minutes), and the value obtained by dividing the initial weight of the raw material liquid by the measured weight was used as the weight-based concentration factor at that time point. In addition, the raw material liquid was sampled at predetermined intervals (10 minutes) and - The ion concentration was measured by ion chromatography (manufactured by Tosoh Technosystems Co., Ltd., model "IC-2010").

[0122] The results are shown in Tables 5-1 and 5-2 and in FIG.

[0123] [Table 47]

[0124] [Table 48]

[0125] (6) Forward osmosis concentration using a radioactive iodine aqueous solution as the starting solution As the raw material liquids, 200 g of each of the following two aqueous solutions was used. An aqueous solution of iodine-131 (131I) dissolved in distilled water to a radioactivity concentration of 100 Bq / g, and A solution of iodine-131 (131I) dissolved in rainwater to a radioactivity concentration of 100 Bq / g. In the above, a standard solution containing 0.05 mg / g NaI, 0.03 mg / g NaOH, and 0.02 mg / g NaSO was used as iodine-131 (I). Rainwater collected in Fukushima City, Fukushima Prefecture was used. As the induction liquid, 200 g of a magnesium chloride solution with a concentration of 1.0 mol / L was used.

[0126] The feed solution was supplied to the inside of the hollow fibers of the forward osmosis membrane module, and the draw solution was supplied to the outside of the hollow fibers at a flow rate of 60 mL / min in parallel. After passing through the forward osmosis membrane module, the feed solution and draw solution were returned to the feed solution tank and draw solution tank, respectively, and a concentration operation was performed by forward osmosis using a circulation system. The concentration operation was repeated three times for each aqueous solution. The weight of the raw material liquid was measured at predetermined time intervals (10 minutes), and the value obtained by dividing the initial weight of the raw material liquid by the measured weight was used as the weight-based concentration factor at that time point. In addition, 1.0 g of the raw material solution and the concentrated derivative solution were sampled every predetermined time (10 minutes), and the collected solution was soaked into filter paper in a petri dish. The radioactivity concentration of 131I was measured using a Ge semiconductor detector, and the concentration ratio of 131I was calculated by dividing the radioactivity concentration after concentration by the radioactivity concentration before concentration.

[0127] The results are shown in Tables 6-1 to 6-6 and FIG.

[0128] [Table 49]

[0129] [Table 50]

[0130] [Table 51]

[0131] [Table 52]

[0132] [Table 53]

[0133] [Table 54]

[0134] In the first experiment using rainwater, the balance of radioactivity was confirmed. The radioactivity in the raw solution before concentration was 20,101 Bq (= 100.5 Bq / g × 200.05 g), and the radioactivity in the induction solution was 0 Bq (below the lower limit of quantification). In contrast, after concentrating to a concentration ratio of 10.67 times, The radioactivity in the raw material liquid was 17,078 Bq (= 911.0 Bq / g × 18.75 g), The radioactivity in the sample taken for analysis was 1,322 Bq. The radioactivity in the induction solution was 60 Bq. The radioactivity contained in the cleaning solution used to wash the piping and membrane module after concentration was 665 Bq. Therefore, the recovery rate of 131I before and after enrichment was (17,078Bq + 1,322Bq + 665Bq) / 20,101Bq = 19,065Bq / 20,101Bq = 94.8%, confirming that 131I was enriched with a high recovery rate.

Claims

1. 1. An analytical method for estimating the concentration of an analyte in a stock solution comprising the analyte, a standard, and a solvent, comprising: The analysis method includes a concentration step of concentrating the original solution to obtain a concentrated solution, and a concentration measurement step of measuring the concentrations of the analyte and the standard in the concentrated solution, The concentration step is carried out by forward osmosis or reverse osmosis, The target substance and the standard substance are the same chemical species, and the standard substance contains the element E Ａ Isotope E of Ｓ Including, A measured value C of the concentration of the analyte in the concentrated solution Ａ，１ , the concentration C of the standard in the stock solution Ｓ，０ , the measured concentration C of the standard in the concentrated solution Ｓ，１ , the concentration ratio X of the original solution in the concentration step, and the recovery rate R of the standard substance in the concentration step calculated by the following formula (1) are used to calculate the concentration C of the analyte substance in the original solution by the following formula (2): Ａ，０ Estimate the Analysis method. R=C Ｓ，１ / (X×C Ｓ，０ ) (1) C Ａ，０ =C Ａ，１ / (X×R) (2)

2. The analytical method according to claim 1 , further comprising, before the concentrating step, an adding step of adding the standard substance to a solution to be analyzed containing the substance to be analyzed and a solvent to prepare the original solution.

3. The isotope E in the standard material Ｓ is a radioisotope, a storage step of storing the analyte solution before the adding step, The period of the storage step is Ｓ is more than 10 times the half-life of The analytical method according to claim 2.

4. The element E in the substance to be analyzed Ａ The analytical method according to claim 3, wherein is a radioisotope.

5. The element E Ａ The half-life of the isotope E in the standard material is Ｓ The method of claim 4, wherein the half-life of the antibody is longer than the half-life of the antibody.

6. The element E in the substance to be analyzed Ａ The half-life of the isotope E in the standard material is Ｓ The analytical method according to claim 5, wherein the half-life of the ATP is 10 times or more.

7. Element E in the substance to be analyzed Ａ The analytical method according to claim 6, wherein the half-life of the compound is 100 days or more.

8. The isotope E Ｓ The analytical method according to claim 7, wherein the half-life of the compound is 1 day or more and less than 100 days.

9. The isotope E Ｓ The analytical method according to any one of claims 1 to 6, wherein the half-life of the

10. The analytical method according to any one of claims 1 to 8, wherein the concentration step is carried out by forward osmosis using a forward osmosis membrane.

11. The analytical method according to claim 10, wherein the forward osmosis membrane is a composite semipermeable membrane comprising a support layer and a separation active layer provided on the support layer, and the separation active layer comprises polyamide.

12. The analytical method according to any one of claims 1 to 7, wherein the concentrations of the analyte and the standard substance in the concentration measuring step are measured by one or more methods selected from the group consisting of chromatography, electromagnetic wave analysis, mass spectrometry, ion analysis, radioactivity analysis, electrochemical analysis, thermal analysis, and X-ray analysis.

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