Method, program, and energy-dispersive fluorescent x-ray analysis system

Abstract

This method comprises: a step for acquiring, from a memory in which an analysis range and a background energy range corresponding to each of one or more elements are stored, an analysis range that corresponds to a given target element and a background energy range that corresponds to the target element in order to create a calibration curve for the target element; a step for deriving, for each of one or more standard samples containing the target element at different concentrations, the ratio of the X-ray intensity of the analysis range that corresponds to the target element and the X-ray intensity of the background energy range that corresponds to the target element; and a step for creating a calibration curve for the target element by using the ratios for each of the one or more standard samples.

Description

Method, program, and energy dispersive X-ray fluorescence analysis system

[0001] The present invention relates to the analysis of elements using spectra according to energy dispersive X-ray fluorescence spectroscopy.

[0002] Various studies have been conducted to improve the accuracy of elemental analysis by X-ray fluorescence spectrometry. For example, Japanese Patent Laid-Open Publication No. 2015-001482 (Patent Document 1) proposes a technique for elemental analysis by X-ray fluorescence spectrometry, in which standard samples of a target element at multiple concentrations are prepared, and a calibration curve of the target element is created based on the respective concentrations and detection intensities of the standard samples at the multiple concentrations.

[0003] JP 2015-001482 A

[0004] There may be differences between the sample used to create the calibration curve and the unknown sample in the base material used, the density of the target element, and / or the amount of the sample itself. These differences may cause doubts about the analytical accuracy of the analysis results derived using the calibration curve. However, with an unknown sample, there are many unknown factors, such as the type of base material used and the density of the target element, making it difficult to prepare a sample in advance that matches the unknown sample and create a calibration curve.

[0005] The present invention has been devised in view of the above circumstances, and its purpose is to provide a technique for easily realizing highly accurate analysis.

[0006] A method according to an aspect of the present disclosure includes the steps of: acquiring an analysis range and a background energy range corresponding to a target element from a memory in which analysis ranges and background energy ranges corresponding to each type of element are stored; deriving, for each of one or more standard samples containing the target element at different concentrations, a ratio between the X-ray intensity in the analysis range corresponding to the target element and the X-ray intensity in the background energy range corresponding to the target element; and creating a calibration curve for the target element using the ratios for each of the one or more standard samples.

[0007] A program according to an aspect of the present disclosure causes a computer to perform the above-described method when executed by the computer.

[0008] An energy dispersive X-ray fluorescence analysis system according to an aspect of the present disclosure includes an energy dispersive X-ray fluorescence analyzer and an information processing device that analyzes an unknown sample using a spectrum of the unknown sample measured by the energy dispersive X-ray fluorescence analyzer, and the information processing device includes a memory that stores the program and a processor that executes the program stored in the memory.

[0009] An energy dispersive X-ray fluorescence analysis system according to one aspect of the present disclosure includes: an energy dispersive X-ray fluorescence analyzer; and an information processing device that performs analysis of the unknown sample using the spectrum of the unknown sample measured by the energy dispersive X-ray fluorescence analyzer. The information processing device includes a memory in which an analysis range and a background energy range corresponding to each of one or more elements are stored; and a calibration curve creation unit. The calibration curve creation unit acquires the analysis range and the background energy range corresponding to the target element from the memory, derives the ratio between the X-ray intensity in the analysis range corresponding to the target element and the X-ray intensity in the background energy range corresponding to the target element for each of one or more standard samples containing the target element at different concentrations, and creates a calibration curve for the target element using the ratio for each of the one or more standard samples.

[0010] According to one aspect of the present disclosure, a technique is provided for easily achieving highly accurate analysis.

[0011] 11 is a diagram showing an example of a spectrum in the vicinity of characteristic X-rays of Ni of a standard sample. FIG. 12 is a diagram showing an example of a spectrum in the background energy range of the same Ni standard sample as in FIG. 1. FIG. 13 is a diagram showing an example of a calibration curve created for Ni. FIG. 14 is a diagram schematically showing the overall configuration of an analysis system including an energy dispersive X-ray fluorescence analyzer. FIG. 15 is a diagram showing the hardware configuration of an information processing device 20. FIG. 16 is a diagram showing an example of conditions for creating calibration curves for 23 types of elements. FIG. 17 is a diagram showing an example of a spectrum measured using filter #2. FIG. 18 is a diagram showing an example of a spectrum measured using filter #4. FIG. 19 is a diagram showing another example of a spectrum measured using filter #4. FIG. 19 is a diagram showing an example of a spectrum measured using filter #1. FIG. 19 is a flowchart of processing executed in the X-ray fluorescence analysis system 100. FIG. 19 is a flowchart of a subroutine of step S20 of FIG. 11. FIG. 19 is a diagram for explaining an example of a method for calculating NET intensity.

[0012] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and description thereof will not be repeated.

[0013] [Summary of the Disclosure] In this disclosure, to create a calibration curve for a certain element, the NET intensity in the energy range corresponding to the characteristic X-rays of the element and the intensity in the background energy range (BG intensity) of the element are identified for each of standard samples with multiple concentrations. The NET intensity is the area value surrounded by the peak spectrum and the background. A fitting function may be used to determine the peak spectrum. Then, for each of standard samples with multiple concentrations, the ratio of the former intensity to the latter intensity ([NET intensity / BG intensity]) is calculated. Hereinafter, this ratio may be referred to as the "measured intensity ratio." A calibration curve for the element is then created based on the concentration values ​​of the multiple standard samples and the measured intensity ratio calculated for each concentration.

[0014] For example, nickel (Ni) will be used as an example of an element to more specifically explain the calibration curve creation policy.

[0015] Fig. 1 shows an example of a spectrum of a standard sample in the vicinity of the characteristic X-rays of Ni. Fig. 2 shows an example of a spectrum of the same Ni standard sample in the background energy range.

[0016] In FIG. 1 , waveform W11 represents the detected intensity of X-rays. Waveform W12 represents the intensity of a background generated for waveform W11. The background intensity is derived, for example, according to the Statistically Sensitive Non-Linear Iterative Peak Clipping (SNIP) algorithm. For the SNIP algorithm, see, for example, "Background elimination using the SNIP algorithm for Bragg reflections from a protein crystal measured by a TOF single-crystal neutron diffractometer" (URL: https: / / iopscience.iop.org / article / 10.1088 / 1742-6596 / 664 / 7 / 072049 / pdf#:~:text=The%20statistics%2Dsensitive%20non%2Dlinear,the%20background%20under%20a%20peak.).

[0017] In FIG. 1 , the hatched region represents the difference between waveform W11 and waveform W12 in the energy range corresponding to the characteristic X-rays of Ni. For each element, the "energy range corresponding to the characteristic X-rays" is described below as the "analysis range" with reference to FIG. 6 and is set in advance to include the characteristic X-rays of each element. In one implementation example, a range of 7.28 to 7.68 keV is set for the Ni Kα ray. The peak top of the characteristic X-rays of Ni Kα ray is 7.48 keV. That is, the above range includes the energy of the characteristic X-rays of Ni Kα ray. The area of ​​the hatched region in FIG. 1 is identified as the intensity (NET intensity) of the energy region corresponding to the characteristic X-rays of Ni. Note that the area of ​​the hatched region in FIG. 1 can be calculated as the integral value of the value obtained by subtracting the intensity of waveform W12 from the intensity of waveform W11.

[0018] In FIG. 2, waveform W21 represents the detected intensity of X-rays. Waveform W22 represents the background intensity. The hatched area represents the difference between waveform W21 and waveform W22 in a background energy range preset for Ni. The background energy range is preset for each element. In one implementation example, a range of 8.00 to 9.00 keV is set for Ni. The area of ​​the hatched area in FIG. 2 is specified as the X-ray intensity (BG intensity) in the background energy range of Ni. Note that the area of ​​the hatched area in FIG. 2 can be calculated as the integral value of the intensity of waveform W22.

[0019] Then, the area of ​​the hatched region in FIG. 1 is divided by the area of ​​the hatched region in FIG. 2 to calculate the value (NET intensity (FIG. 1) / BG intensity (FIG. 2), i.e., the measured intensity ratio). The calculated value corresponds to the above-mentioned "ratio" ([NET intensity / BG intensity]).

[0020] FIG. 3 is a diagram showing an example of a calibration curve created for Ni. A measurement intensity ratio is calculated for each of a plurality of concentrations of standard samples for Ni. Each plot in FIG. 3 represents the concentration value and the measurement intensity ratio for each of the concentrations of the plurality of standard samples. Line L1 in FIG. 3 represents the Ni calibration curve created using the plots in FIG. 3.

[0021] 4 is a diagram showing the overall configuration of an analysis system including an energy dispersive X-ray fluorescence analyzer. The X-ray fluorescence analysis system 100 includes an X-ray fluorescence analyzer 10, an information processing device 20, a display 40, and an input unit 34.

[0022] The X-ray fluorescence analyzer 10 is an energy dispersive X-ray fluorescence analyzer that measures the concentration of elements contained in a sample S, and is composed of a sample chamber 1 and a measurement chamber 5. The spaces inside the sample chamber 1 and the measurement chamber 5 are airtightly enclosed by a housing 3, and the interior can be kept vacuum as needed. The interior can also be kept under an atmosphere of a predetermined gas such as helium.

[0023] The sample chamber 1 is provided with a sample stage 2 at the bottom. An opening 4 is formed in the sample stage 2. A sample S is placed on the sample stage 2 so as to cover the opening 4. The sample S is placed on the sample stage 2 so that the measurement position is exposed from the opening 4.

[0024] The XY stage 14 is configured to be able to move the sample S along the in-plane direction of the sample stage 2. The driving mechanism 15 can drive the XY stage 14 in two in-plane axial directions that are perpendicular to each other. This makes it possible to automatically adjust the measurement position of the sample S.

[0025] The measurement chamber 5 is equipped with an X-ray tube 7 and a detector 8 on its wall surface 6. The X-ray tube 7 irradiates primary X-rays toward the sample S. The X-ray tube 7 has a filament that emits thermions and a target that converts the thermions into predetermined primary X-rays and emits them. The primary X-rays emitted by the X-ray tube 7 are irradiated onto the measurement position of the sample S through the opening 4. Secondary X-rays (fluorescent X-rays) emitted by the sample S are incident on the detector 8, and the energy and intensity of the fluorescent X-rays are measured.

[0026] A shutter 9, a primary X-ray filter 11, a collimator 13, and an imaging unit 16 are installed in the measurement chamber 5. The shutter 9, the primary X-ray filter 11, and the collimator 13 are configured to be slidable by a drive mechanism 12 in a direction perpendicular to the plane of the paper in FIG.

[0027] The shutter 9 is made of an X-ray absorbing material such as lead, and can be inserted into the optical path of the primary X-rays to block the primary X-rays when necessary.

[0028] The primary X-ray filter 11 is made of a metal foil selected according to the purpose, and attenuates background components of the primary X-rays emitted from the X-ray tube 7 to improve the S / N ratio of required characteristic X-rays. In an actual device, a plurality of primary X-ray filters 11 made of different types of metal are used, and the primary X-ray filter 11 selected according to the purpose is inserted into the optical path of the primary X-rays by a drive mechanism 12.

[0029] The collimator 13 is an aperture with a circular opening in the center, and determines the size of the primary X-ray beam that irradiates the sample S. The collimator 13 is made of an X-ray absorbing material such as lead or brass. In an actual device, multiple collimators 13 with different opening diameters are arranged side by side in a direction perpendicular to the plane of the paper in FIG. 1 , and the collimator 13 selected according to the purpose is inserted into the primary X-ray beam line by the driving mechanism 12.

[0030] The imaging unit 16 is installed at the bottom of the measurement chamber 5. The imaging unit 16 is configured to capture an image of the measurement position of the sample S through an opening 4 formed in the sample stage 2. The imaging unit 16 includes an imaging element partitioned into a plurality of pixels, such as a CMOS (Complementary Metal Oxide Semiconductor) or a CCD (Charge Coupled Device). Image data from the imaging unit 16 is transmitted to an information processing device 20.

[0031] 5 is a diagram showing the hardware configuration of the information processing device 20. The information processing device 20 is mainly composed of a CPU (Central Processing Unit) 22, which is an arithmetic processing unit. The information processing device 20 may be, for example, a personal computer.

[0032] The information processing device 20 further includes a storage unit that non-temporarily stores programs and data. The information processing device 20 operates in accordance with the programs executed by the CPU 22. The storage unit includes a read-only memory (ROM) 24, a random access memory (RAM) 26, and a hard disk drive (HDD) 30. Note that specific examples of the storage unit are not limited to these.

[0033] The information processing device 20 further has an I / O (Input / Output) interface 28 and a communication interface 32. The communication interface 32 is an interface that allows the information processing device 20 to communicate with external devices including the X-ray fluorescence analyzer 10. The I / O interface 28 is an interface for input to or output from the information processing device 20. As shown in FIG. 2 , the I / O interface 28 is connected to an input unit 34 and a display 40. The input unit 34 is, for example, a keyboard and / or a mouse, and accepts input, including instructions for the information processing device 20, from the operator.

[0034] Returning to FIG. 4, the information processing device 20 is connected with the input unit 34 and the display 40 as well as the X-ray tube 7, the detector 8, and the imaging unit 16.

[0035] The information processing device 20 controls the X-ray fluorescence analyzer 10 based on the measurement conditions and the like input by the input unit 34. Specifically, the information processing device 20 controls the tube voltage, tube current, irradiation time, and the like of the X-ray tube 7, and also drives each of the shutter 9, primary X-ray filter 11, and collimator 13.

[0036] During measurement, the information processing device 20 acquires the spectrum of the secondary X-rays detected by the detector 8. The information processing device 20 performs quantitative analysis of each element based on the spectrum of the secondary X-rays detected by the detector 8.

[0037] The information processing device 20 further controls the imaging by the imaging unit 16, and before measurement, automatically detects a measurement position of the sample S based on image data acquired by the imaging unit 16. The information processing device 20 further selects a collimator 13 having an optimal opening diameter for the detected measurement position from among a plurality of collimators 13. The display 40 can display the image of the sample S imaged by the imaging unit 16, as well as the format of a report created by the information processing device 20.

[0038] [Example of conditions set for each element] On December 16, 2014, the International Council for Harmonization of Technical Requirements for Pharmaceuticals for human use (known as the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use in Japan) announced new guidelines for the management of elemental impurities in pharmaceutical formulations (ICH HARMONISED GUIDELINE, International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use in Japan, December 16, 2014, Internet, <URL: https: / / www.pmda.go.jp / files / 000197758.pdf>: Non-Patent Document 1). The present disclosure covers the creation of calibration curves for 23 elements, excluding Li, of the 24 elements defined as impurity elements in this guideline, "ICH-Q3D."

[0039] 6 is a diagram showing an example of conditions for creating calibration curves for 23 elements. In one implementation example, the conditions shown in FIG.

[0040] The table shown in FIG. 6 includes seven items (elements, analytical lines, characteristic X-rays, analysis range of NET intensity, analytical filter, BG filter, and BG range).

[0041] Element represents the type of element of interest. 23 types of elements are shown in Fig. 6, namely, arsenic (As), mercury (Hg), lead (Pb), cadmium (Cd), vanadium (V), cobalt (Co), nickel (Ni), iridium (Ir), platinum (Pt), ruthenium (Ru), rhodium (Rh), palladium (Pd), chromium (Cr), copper (Cu), thallium (Tl), selenium (Se), silver (Ag), barium (Ba), osmium (Os), gold (Au), molybdenum (Mo), tin (Sn), and antimony (Sb).

[0042] The analytical lines indicate the types of characteristic X-rays used in the analysis. For V, information about each of the two analytical lines (Kα and Kβ1) is shown.

[0043] The characteristic X-rays represent the energy of the characteristic X-rays used in the analysis. The analysis range of the NET intensity represents the energy range of the NET intensity used in creating the calibration curve and in the analysis. The analysis range of the NET intensity includes the characteristic X-rays of each element and is an example of an energy range corresponding to the characteristic X-rays of each element.

[0044] The analysis filter indicates the type of primary X-ray filter 11 used to measure the spectrum for specifying the intensity in the analysis range of the NET intensity.

[0045] The BG filter represents a type of primary X-ray filter 11 used for measuring a spectrum to identify the intensity of the BG range, which will be described later. However, the filter shown as the "BG filter" in Fig. 6 does not necessarily have to be used for measuring a spectrum to identify the intensity of the BG range. The primary X-ray filter 11 does not necessarily have to be used for measuring a spectrum to identify the intensity of the BG range.

[0046] The BG range represents the background energy range described above. For example, for As, an example background energy range is 10.50-13.50 keV.

[0047] (Analysis Range and Background Energy Range) For Hg, V, Ru, Rh, Pd, Cr, Ag, and Mo, the background energy range does not overlap with the analysis range and is located on the higher energy side than the analysis range.

[0048] For As, Pb, Cd, Co, Ni, Ir, Pt, Tl, Se, Os, and Au, the background energy range partially overlaps with the analysis range but is located on the higher energy side than the analysis range.

[0049] For Cu, the background energy range partially overlaps with the analysis range, but is located on the higher energy side than the analysis range.

[0050] For Ba, the background energy range is located on the lower energy side than the analysis range.

[0051] For Sn and Sb, the background energy range has a common energy range with the analysis range.

[0052] (Analysis Filters and BG Filters) FIG. 6 shows three types of filters (#4, #2, #1) that represent analysis filters or BG filters.

[0053] 6, there are four types of combinations of analysis filters and background green filters. In the first type, #4 is used as the analysis filter and #2 is used as the background green filter. This type includes As, Hg, Pb, Co, Ni, Ir, Pt, Cu, Tl, Se, Os, and Au.

[0054] In the second type, #1 is used as an analytical filter and #2 is used as a BG filter. This type includes Cd, Ru, Rh, Pd, Ag, Ba, and Mo.

[0055] In the third type, #2 is used as an analysis filter and #2 is used as a BG filter. V and Cr belong to this type.

[0056] In the fourth type, #1 is used as an analysis filter and #1 is used as a BG filter. This type includes Sn and Sb.

[0057] Figure 7 shows an example of a spectrum measured using filter #2. In the example shown in Figure 7, an aqueous solution sample not containing the target element was used. That is, waveform W31 in Figure 7 represents the fluorescence spectrum of the aqueous solution sample. Note that, since the measurement was performed in an air atmosphere, argon (Ar) in the air was detected. Figure 7 also shows the energy positions of characteristic X-rays for Kα and Kβ of V and Kα of Cr.

[0058] Fig. 8 shows an example of a spectrum measured using filter #4. In the example shown in Fig. 8, a sample containing iron (Fe), Ni, and Cu is used as the measurement target. That is, waveform W41 in Fig. 8 represents the fluorescence spectrum of the sample containing Fe, Ni, and Cu. Fig. 8 also shows the energy positions of the characteristic X-rays of Co, Ni, Cu, As, and Se.

[0059] Figure 9 shows another example of a spectrum measured using filter #4. In the example of Figure 9, similar to the example of Figure 8, a sample containing Fe, Ni, and Cu is used as the measurement target. That is, waveform W51 in Figure 9 represents the fluorescence spectrum of a sample containing Fe, Ni, and Cu. Figure 9 also shows the energy positions of characteristic X-rays of Os, Ir, Pt, Au, Hg, Tl, and Pb.

[0060] Fig. 10 shows an example of a spectrum measured using filter #1. In the example of Fig. 10, an aqueous solution sample that does not contain the target elements (the 23 elements shown in Fig. 6) is used as the sample to be measured. That is, waveform W61 in Fig. 10 represents the fluorescence spectrum of the aqueous solution sample. Fig. 10 also shows the energy positions of the characteristic X-rays of Mo, Ru, Rh, Pd, Ag, Cd, Sn, Sb, and Ba.

[0061] 11 is a flowchart of processing executed in the X-ray fluorescence analysis system 100. In one implementation example, the processing in FIG. 11 is started by starting an analysis application program in the information processing device 20.

[0062] 11 , in step S10, the X-ray fluorescence analysis system 100 determines whether or not an instruction to create a calibration curve has been received. In one implementation example, when an analysis application program is started, a start-up screen is displayed on the display 40. The start-up screen includes one or more keys for selecting a menu. When a key for creating a calibration curve is operated on the start-up screen of the display 40, an instruction to create a calibration curve is input to the X-ray fluorescence analysis system 100.

[0063] If fluorescent X-ray analysis system 100 determines that it has received an instruction to create a calibration curve (YES in step S10), it proceeds to step S20; otherwise (NO in step S10), it proceeds to step S30.

[0064] In step S20, the X-ray fluorescence analysis system 100 performs control for creating a calibration curve, and then the control proceeds to step S30.

[0065] FIG. 12 is a flowchart of the subroutine of step S20 in FIG. 11. The control of calibration curve creation will be described with reference to FIG. 12. It is assumed that the type of element for which the calibration curve is to be created is specified. Furthermore, the creation of the calibration curve utilizes, for each element, an analytical spectrum and a BG spectrum measured for each of M types of standard samples (M is an integer that is appropriately set). The analytical spectrum is a spectrum measured using the "analysis filter" in FIG. 6. The BG spectrum is a spectrum measured using the "BG filter" in FIG. 6.

[0066] For example, if ten types of standard samples are used to create a calibration curve for a certain element, ten analytical spectra and ten BG spectra are measured and used. Each spectrum may be measured in advance by the X-ray fluorescence analyzer 10 and stored in the HDD 30, or may be measured in parallel with the control of FIG. 12.

[0067] 12, in step S200, fluorescent X-ray analysis system 100 sets the value of variable N used in the control of FIG. 12 to 1, and reads out the conditions (FIG. 6) for creating a calibration curve for the element to be analyzed.

[0068] In step S202, the X-ray fluorescence analysis system 100 reads out the analysis spectrum of the Nth standard sample among the M types of standard samples.

[0069] In step S204, the X-ray fluorescence analysis system 100 identifies the NET intensity of the target element from the analysis spectrum read out in step S202. The NET intensity can be calculated, for example, according to the method described with reference to FIG.

[0070] In step S206, the X-ray fluorescence analysis system 100 reads out the BG spectrum of the Nth standard sample among the M types of standard samples.

[0071] In step S208, the X-ray fluorescence analysis system 100 identifies the BG intensity of the target element from the BG spectrum read out in step S206. The BG intensity can be calculated, for example, according to the aspect described with reference to FIG.

[0072] In step S210, the X-ray fluorescence analysis system 100 determines whether the value of variable N has reached M. If the X-ray fluorescence analysis system 100 determines that the value of variable N has not reached M (NO in step S210), it updates N by incrementing it by 1 in step S212 and returns control to step S202. If the X-ray fluorescence analysis system 100 determines that the value of variable N has reached M (YES in step S210), it proceeds to step S214.

[0073] In step S214, the X-ray fluorescence analysis system 100 calculates the ratio of the NET intensity to the BG intensity (NET intensity / BG intensity) for each of the N types of standard samples, thereby calculating N "ratios."

[0074] In step S216, the X-ray fluorescence analysis system 100 identifies an approximation line using the N "proportions" calculated in step S214. The identified approximation line is stored in the HDD 30 as a calibration curve for the target element.

[0075] Thereafter, the X-ray fluorescence analysis system 100 returns the process to Fig. 11 . Returning to Fig. 11 , in step S30, the X-ray fluorescence analysis system 100 determines whether or not an instruction to analyze the sample to be analyzed has been received. In one implementation example, when an analysis key for the sample to be analyzed is operated on the startup screen of the display 40, an analysis instruction is input to the X-ray fluorescence analysis system 100. If the X-ray fluorescence analysis system 100 determines that the instruction to analyze has been received (YES in step S30), it proceeds to control to step S40. If the X-ray fluorescence analysis system 100 determines that the instruction to analyze has not been received (NO in step S30), it returns control to step S10. When returning control to step S10, the X-ray fluorescence analysis system 100 displays the startup screen on the display 40.

[0076] In step S40, the X-ray fluorescence analysis system 100 derives the content of the target element in the sample to be analyzed. The content is derived using a (set of) spectra of the sample to be analyzed. The (set of) spectra of the sample to be analyzed includes a spectrum measured using an analysis filter ( FIG. 6 ) and a spectrum measured using a BG filter ( FIG. 6 ). The (set of) spectra of the sample to be analyzed may be acquired by the X-ray fluorescence analysis apparatus 10 in step S40, or may be acquired in advance and stored in the HDD 30.

[0077] More specifically, in step S40, the X-ray fluorescence analysis system 100 reads the calibration curve for the target element, identifies the NET intensity from the spectrum measured using the analytical filter, identifies the BG intensity from the spectrum measured using the BG filter, calculates the above-mentioned "ratio" from the NET intensity and the BG intensity, and applies the "ratio" to the calibration curve to derive the content of the target element.

[0078] In step S50, the X-ray fluorescence analysis system 100 displays the analysis results (element contents) derived in step S40 on the display 40. Thereafter, control returns to step S10. When returning control to step S10, the X-ray fluorescence analysis system 100 displays the above-mentioned start-up screen on the display 40.

[0079] In the process described with reference to FIGS. 11 and 12, not only the intensity in the energy range corresponding to the characteristic X-rays of the target element (NET intensity) but also the intensity in the background energy range (BG intensity) are used in creating and analyzing the calibration curve of the target element.

[0080] In the spectrum of a standard sample, the intensity in the energy range corresponding to the characteristic X-rays of the target element is affected by the content of the target element, the type of base material, the density of the target sample, and / or the characteristics of the standard sample itself, such as the amount of the sample itself (size, thickness / depth), etc. On the other hand, in the spectrum of a standard sample, the intensity in the background energy range is affected by the characteristics of the sample itself.

[0081] In the present disclosure, the ratio of the NET intensity in the optimal energy range for a target element to the X-ray intensity in the optimal background energy range for the target element in the spectrum of a standard sample is used to create a calibration curve for the target element. More specifically, the value derived by dividing the NET intensity by the X-ray intensity in the background energy range (i.e., the measured intensity ratio) is used to create a calibration curve for the target element. This reduces the influence of the characteristics of the standard sample itself on the created calibration curve, and there is no need to consider questions about analytical accuracy arising from the characteristics of the standard sample itself in the analysis results using the calibration curve. Therefore, highly accurate analysis can be achieved without creating multiple calibration curves that take into account the characteristics of the sample itself.

[0082] Fig. 13 is a diagram for explaining an example of a method for calculating the NET intensity. Fig. 13 shows a fluorescent X-ray spectrum determined for a powder sample containing Ni. In the present disclosure, the NET intensity may be calculated using the spectrum determined using a fitting function.

[0083] More specifically, a fluorescence spectrum is obtained as a measurement result of the sample, and a spectrum to be used in calculating the NET intensity is identified by applying fitting using a fitting function to the peak spectrum to be analyzed. As an example, consider the case where a fluorescence spectrum is obtained from a powder sample containing Ni. The peak spectrum of the Ni Kα characteristic X-rays is shown as waveform W73 in FIG. 13. The spectrum identified by applying fitting to the peak spectrum is shown as waveform W71 in FIG. 13. Note that waveform W72 in FIG. 13 represents the background intensity identified for waveform W71. Then, in this example, the integrated value of the difference between waveform W71 and waveform W72 in the hatched region in FIG. 13 is calculated as the NET intensity.

[0084] Aspects It will be understood by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0085] (Item 1) A method according to one aspect may include the steps of: acquiring an analysis range corresponding to a target element and a background energy range corresponding to the target element from a memory in which an analysis range and a background energy range corresponding to each of one or more elements are stored; deriving, for each of one or more standard samples containing the target element at different concentrations, a ratio between the X-ray intensity in the analysis range corresponding to the target element and the X-ray intensity in the background energy range corresponding to the target element; and creating a calibration curve for the target element using the ratio for each of the one or more standard samples.

[0086] According to the method according to the first aspect, a technique for easily realizing highly accurate analysis is provided.

[0087] (Item 2) In the method according to item 1, the background energy range may be located on the higher energy side than the energy of characteristic X-rays of the element.

[0088] According to the method according to the second aspect, the X-ray intensity in the background energy range can be appropriately obtained for a specific element.

[0089] (Item 3) In the method according to item 2, the element may be As, Hg, Pb, Cd, V, Co, Ni, Ir, Pt, Ru, Rh, Pd, Cr, Tl, Se, Ag, Os, Au, or Mo, and the background energy range may include a range in Table 1 below.

[0090]

[0091] According to the method according to the third aspect, the X-ray intensity in the background energy range can be more appropriately obtained for a specific element.

[0092] (Item 4) In the method according to item 1, the background energy range may include the energy of characteristic X-rays of the element.

[0093] According to the method of the fourth aspect, the X-ray intensity in the background energy range can be appropriately obtained for a specific element.

[0094] (Item 5) In the method according to any one of Items 1 to 4, the intensity of an energy range corresponding to characteristic X-rays of the element may be identified from a first spectrum measured using a first filter, and the X-ray intensity of the element in the background energy range may be identified from a second spectrum measured using a second filter.

[0095] According to the method of the fifth aspect, both the intensity in the energy range corresponding to the characteristic X-rays of an element and the X-ray intensity in the background energy range of the element can be appropriately obtained.

[0096] (Item 6) The method according to item 5 may further include a step of identifying the content of the element in the sample to be analyzed by using the calibration curve and a spectrum obtained for the sample to be analyzed according to energy dispersive X-ray fluorescence spectrometry.

[0097] According to the method of the sixth aspect, the content of an element in a sample to be analyzed can be derived without being affected by the characteristics of the sample itself, such as the base material.

[0098] (Clause 7) A program according to one aspect may cause a computer to carry out the method according to any one of clauses 1 to 6 when executed by the computer.

[0099] The program according to the seventh aspect provides a technique for easily achieving highly accurate analysis.

[0100] (Item 8) An energy dispersive X-ray fluorescence analysis system according to one aspect includes an energy dispersive X-ray fluorescence analyzer and an information processing device that analyzes an unknown sample using a spectrum of the unknown sample measured by the energy dispersive X-ray fluorescence analyzer, and the information processing device may include a memory that stores the program described in item 7, and a processor that executes the program stored in the memory.

[0101] The energy dispersive X-ray fluorescence analysis system according to the eighth aspect provides a technique for easily achieving highly accurate analysis.

[0102] (Item 9) An energy dispersive X-ray fluorescence analysis system according to one aspect includes an energy dispersive X-ray fluorescence analyzer and an information processing device that analyzes an unknown sample using a spectrum of the unknown sample measured by the energy dispersive X-ray fluorescence analyzer, wherein the information processing device includes a memory in which an analysis range and a background energy range corresponding to each of one or more elements are stored, and a calibration curve creation unit, wherein the calibration curve creation unit obtains from the memory the analysis range corresponding to a target element and the background energy range corresponding to the target element, and derives, for each of one or more standard samples containing the target element at different concentrations, a ratio between the X-ray intensity in the analysis range corresponding to the target element and the X-ray intensity in the background energy range corresponding to the target element, and creates a calibration curve for the target element using the ratio for each of the one or more standard samples.

[0103] The energy dispersive X-ray fluorescence analysis system according to the ninth aspect provides a technique for easily achieving highly accurate analysis.

[0104] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not by the description of the above-described embodiments, and is intended to include all modifications within the meaning and scope of the claims. Furthermore, it is intended that each technique in the embodiments can be implemented alone or, if necessary, in combination with other techniques in the embodiments to the extent possible.

[0105] 10 X-ray fluorescence analyzer, 11 primary X-ray filter, 20 information processing device, 100 ray analysis system.

Claims

1. A method comprising the steps of: obtaining an analysis range corresponding to a target element and a background energy range corresponding to the target element from a memory in which an analysis range and a background energy range corresponding to each of one or more elements are stored; deriving, for each of one or more standard samples containing the target element at different concentrations, a ratio between the X-ray intensity in the analysis range corresponding to the target element and the X-ray intensity in the background energy range corresponding to the target element; and creating a calibration curve for the target element using the ratio for each of the one or more standard samples.

2. The method of claim 1, wherein the background energy range is located on the higher energy side than the energy of the characteristic X-rays of the target element.

3. The method of claim 2, wherein the target element is As, Hg, Pb, Cd, V, Co, Ni, Ir, Pt, Ru, Rh, Pd, Cr, Tl, Se, Ag, Os, Au, or Mo, and the background energy range includes the ranges in Table 1 below.

4. The method of claim 1, wherein the background energy range includes the energies of characteristic x-rays of the element of interest.

5. The method of claim 1, wherein an intensity in an energy range corresponding to characteristic X-rays of the target element is identified from a first spectrum measured using a first filter, and an X-ray intensity in the background energy range of the target element is identified from a second spectrum measured using a second filter.

6. The method according to claim 5, further comprising a step of determining the content of the target element in the sample to be analyzed using the calibration curve and a spectrum obtained for the sample to be analyzed according to energy dispersive X-ray fluorescence spectrometry.

7. A program which, when executed by a computer, causes the computer to carry out the method of claim 1.

8. An energy dispersive X-ray fluorescence analysis system comprising: an energy dispersive X-ray fluorescence analysis device; and an information processing device that performs analysis of an unknown sample by utilizing the spectrum of the unknown sample measured by the energy dispersive X-ray fluorescence analysis device, wherein the information processing device comprises: a memory that stores the program according to claim 7; and a processor that executes the program stored in the memory.

9. An energy dispersive X-ray fluorescence analysis system comprising: an energy dispersive X-ray fluorescence analyzer; and an information processing device that performs analysis of an unknown sample by utilizing the spectrum of the unknown sample measured by the energy dispersive X-ray fluorescence analyzer, wherein the information processing device includes: a memory in which an analysis range and a background energy range corresponding to each of one or more elements are stored; and a calibration curve creation unit, wherein the calibration curve creation unit obtains from the memory an analysis range corresponding to a target element and a background energy range corresponding to the target element, for each of one or more standard samples containing the target element in different concentrations, derives a ratio between the X-ray intensity in the analysis range corresponding to the target element and the X-ray intensity in the background energy range corresponding to the target element, and creates a calibration curve for the target element by using the ratio for each of the one or more standard samples.

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