Fluorescent x-ray analysis device

Abstract

A fluorescent X-ray analysis device (10) includes: a sample stage (2); an X-ray tube (7) that is configured so as to radiate excitation X-rays toward the sample stage (2); a detector (8) that detects fluorescent X-rays emitted from a sample on the sample stage; and a control device (14) that controls the X-ray tube (7) and the detector (8). When creating a calibration curve by radiating the excitation X-rays on a standard sample from the X-ray tube (7), the control device (14) issues a warning in the case in which the values of IR / IC obtained with respect to the standard sample fall outside a reference range, assuming that the intensity of X-rays that undergo Rayleigh scattering is IR and the intensity of X-rays that undergo Compton scattering is IC, said X-rays being the results of the sample (S) on the sample stage (2) scattering fluorescent X-rays emitted from the X-ray tube (7) with respect to an X-ray tube bulb target material.

Description

X-ray fluorescence analyzer

[0001] The present disclosure relates to an X-ray fluorescence analyzer.

[0002] X-ray fluorescence analysis is an analytical method in which a sample is irradiated with X-rays and the fluorescent X-rays emitted from the sample are measured to analyze the constituent elements of the sample.

[0003] For example, the X-ray fluorescence analyzer disclosed in Japanese Patent Laid-Open No. 2015-94643 (Patent Document 1) uses a "calibration curve" obtained by measuring in advance the relationship between "element concentration D" and "fluorescent X-ray intensity I per excitation X-ray intensity Iex" using a standard sample S. The calibration curve allows the intensity of fluorescent X-rays emitted from an unknown sample to be converted into the concentration of a detected component in the unknown sample.

[0004] JP 2015-94643 A

[0005] The calibration curve is created by measuring the fluorescent X-ray intensity Ia per tube current using a standard sample containing element a at a known concentration or content (hereinafter, typically referred to as "concentration") Da. The number of standard samples may be one, but multiple standard samples with different concentrations Da are often used.

[0006] However, when creating a calibration curve using multiple standard samples with an X-ray fluorescence analyzer, if the user mistakenly loads a sample other than the standard sample that should be used, the calibration curve will be incorrect, and the quantitative value of the unknown sample using that calibration curve will contain a large error.In addition, if the base material of the calibration curve and the base material of the unknown sample are different, the error in the quantitative result will also be large.

[0007] An object of the present disclosure is to provide an X-ray fluorescence analyzer that can detect when a sample is inappropriate and suppress measurement errors when a calibration curve is used.

[0008] A first aspect of the present disclosure relates to an X-ray fluorescence analyzer for analyzing constituent elements of a sample. The X-ray fluorescence analyzer includes a sample stage on which a sample is placed, an X-ray tube including a target that receives thermal electrons and emits X-rays, and configured to irradiate excitation X-rays including fluorescent X-rays of the target material toward the sample stage, a detector that detects the fluorescent X-rays emitted from the sample on the sample stage, and a control device that controls the X-ray tube and the detector. When a calibration curve is created by irradiating a standard sample with excitation X-rays from the X-ray tube and creating a calibration curve, the control device is configured to issue a warning if the IR / IC value obtained for the standard sample is outside a first reference range, where IR is the intensity of X-rays Rayleigh-scattered by the sample placed on the sample stage from the fluorescent X-rays of the target material and IC is the intensity of X-rays Compton-scattered by the sample placed on the sample stage from the fluorescent X-rays of the target material.

[0009] The fluorescent X-ray analyzer of the present disclosure detects and notifies the user that the sample selection is inappropriate when creating a calibration curve, thereby preventing the measurement error from increasing.

[0010] 1 is a diagram showing an outline of the overall configuration of an X-ray fluorescence analyzer. It is a functional block diagram of a detector 8 and a control device 14. It is a diagram showing an X-ray spectrum of excitation X-rays emitted from an X-ray tube. It is a diagram showing an X-ray spectrum of X-rays detected by a detector 8 when excitation X-rays are incident on a sample S. It is a flowchart for explaining the process of creating a calibration curve executed by a control device in embodiment 1. It is a diagram for explaining an intensity ratio R and a reference range. It is a flowchart for explaining the process of creating a calibration curve executed by a control device in embodiment 2. It is a diagram for explaining a calibration curve and its reference range. It is a flowchart for explaining the process of specifying a concentration using a calibration curve executed by a control device in embodiment 3.

[0011] Hereinafter, embodiments 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.

[0012] [First Embodiment] Fig. 1 is a diagram showing a schematic overall configuration of an X-ray fluorescence analyzer 10. The X-ray fluorescence analyzer 10 shown in Fig. 1 includes a sample chamber 1, a measurement chamber 5, a control device 14, an operation unit 15, and an output unit 16.

[0013] The X-ray fluorescence analyzer 10 is an energy dispersive X-ray fluorescence spectrometer (EDX) that measures the concentration of elements contained in a sample S. The spaces inside the sample chamber 1 and measurement chamber 5 are enclosed airtightly by a housing 3, and the inside can be kept vacuum as needed.

[0014] The sample chamber 1 is provided with a sample stage 2 at its bottom, on which multiple samples S can be placed. The sample stage 2 has multiple (e.g., 12) openings 20 for placing the samples S. The samples S are placed on the sample stage 2 so as to cover the openings 20. This sample stage 2 can be rotated to switch between samples S to be analyzed, and is called a turret. The sample S has a front surface SA, which has a measurement position, and a back surface SB, which is located opposite the front surface SA. During measurement, the rotational position of the sample stage 2 is determined so that the measurement position on the front surface SA of the sample S is exposed through the opening 4 at the bottom of the housing 3.

[0015] The measurement chamber 5 is provided 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 primary X-rays emitted from the X-ray tube 7 are irradiated onto a measurement position on the sample S through the opening 4. Secondary X-rays (fluorescent X-rays) emitted from the sample S are incident on the detector 8, and the energy and intensity of the fluorescent X-rays are measured.

[0016] A shutter 9, a primary X-ray filter 11, and a collimator 13 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] The control device 14 is mainly composed of a CPU (Central Processing Unit) 141, which is an arithmetic processing unit. A personal computer, for example, can be used as the control device 14. The X-ray tube 7, the detector 8, and the output unit 16 are connected to the control device 14.

[0021] The control device 14 controls the measurement by the X-ray fluorescence analyzer 10 based on measurement conditions input via an operation unit 15 including a keyboard, mouse, etc. Specifically, the control device 14 controls the tube voltage, tube current, irradiation time, etc. of the X-ray tube 7, and also drives the shutter 9, primary X-ray filter 11, and collimator 13 using a drive mechanism 12. The operation unit 15 may be a touch panel that is integrated with the display screen of the display device.

[0022] The control device 14 also acquires data of the secondary X-rays detected by the detector 8. The control device 14 performs quantitative analysis of each element based on the spectrum of the secondary X-rays detected by the detector 8.

[0023] The output unit 16 includes a display device configured, for example, by an LCD (Liquid Crystal Display) or an organic EL (Electro Luminescence). The display device displays an image according to data transmitted from the control device 14. The display device can display various images generated by the control device 14. The display device can also display the analysis results by the control device 14 together with identification information for identifying the sample S (product name, product number, measurement position, etc.).

[0024] The control device 14 includes a CPU 141 and a memory 142 that stores programs and data. The memory 142 includes a read-only memory (ROM), a random access memory (RAM), and a solid-state drive (SSD). The memory 142 may include a hard disk drive (HDD) instead of the SSD.

[0025] The ROM stores the programs executed by the CPU 141. The RAM temporarily stores data used during execution of the programs by the CPU 141 and functions as a temporary data memory used as a work area. The SSD is a non-volatile storage device that stores the measurement results obtained by the X-ray fluorescence analyzer 10.

[0026] 2 is a functional block diagram of the detector 8 and the control device 14. The CPU 141 executes a program to cause the operation of each functional block of the control device 14 in FIG.

[0027] The detector 8 includes an X-ray detector 81, a preamplifier 82, and a proportional amplifier 83. The control device 14 includes an A / D converter (ADC) 106, a multi-channel analyzer (MCA) 107, a data processing unit 110, and a control unit 115. The data processing unit 110 includes a spectrum storage unit 111, a peak extraction unit 112, and a discrimination unit 113.

[0028] The X-ray tube 7 has a filament that emits thermoelectrons and a target T that converts the thermoelectrons into predetermined primary X-rays and emits the primary X-rays. A metal such as rhodium is used for the target T. The control unit 115 controls the tube voltage of the X-ray tube to adjust the X-ray intensity.

[0029] When the sample S is irradiated with primary X-rays (excitation X-rays) emitted from the X-ray tube 7, secondary X-rays (including fluorescent X-rays of the sample S) excited by the primary X-rays are emitted from the sample S, and are incident on an X-ray detector 81 such as a silicon drift detector and detected as a current signal. In addition, a portion of the excitation X-rays irradiated on the sample S is scattered by the sample S, and such scattered X-rays are also detected by the X-ray detector 81.

[0030] The detected current is integrated inside the X-ray detector 81, and the integrated value is reset after a certain period of time has elapsed. As a result, the output signal of the X-ray detector 81 becomes a stepped current pulse signal. The height of each step in this signal corresponds to the energy of each element contained in the sample S. This current pulse signal is input to a preamplifier 82 and further to a proportional amplifier 83 including a waveform shaping circuit, where it is shaped into a pulse of an appropriate shape having a wave height corresponding to the height of each step and is then output.

[0031] An A / D converter (ADC) 106 samples and digitizes this pulse waveform analog signal at a predetermined sampling period. A multi-channel analyzer (MCA) 107 discriminates each pulse by energy according to the peak value of the digitized pulse signal, counts each pulse, creates a pulse height distribution diagram, i.e., an X-ray spectrum, and inputs it to a data processing unit 110. The data constituting the X-ray spectrum is stored in a spectrum storage unit 111.

[0032] Fig. 3 is a diagram showing the X-ray spectrum of the excitation X-rays emitted from the X-ray tube, and Fig. 4 is a diagram showing the X-ray spectrum of the X-rays that are incident on the sample S and detected by the detector 8.

[0033] As shown in FIG. 3, the excitation X-rays emitted from the X-ray tube include continuous X-rays that do not show a peak, and fluorescent X-rays RhKα and RhKβ that show peaks derived from rhodium (Rh), which is the target element of the X-ray tube 7.

[0034] As shown in FIG. 4, the X-ray spectrum detected by the detector 8 shows peaks of the spectral lines of Compton scattered X-rays RhKαC and Rayleigh scattered X-rays RhKα originating from the target element of the X-ray tube 7.

[0035] Although not shown in FIG. 4, a spectral line SKα specific to each element appears as a peak at a position corresponding to the energy value of the fluorescent X-rays emitted from the elements contained in the sample S to be analyzed.

[0036] In the data processing unit 110, the peak extraction unit 112 detects each peak appearing in the X-ray spectrum and extracts the peak of the target element or compound. The discrimination unit 113 uses the intensity of each extracted peak, i.e., the X-ray intensity value, to perform a process of discriminating the type of resin contained in the sample. In this embodiment, when creating a calibration curve and when analyzing a sample using the calibration curve, this discrimination unit 113 performs a confirmation process for the sample placed by the user.

[0037] The calibration curve method is explained below. In this method, a calibration curve showing the relationship between X-ray intensity and element concentration (or content rate) is prepared in advance from the results of measuring standard samples, and the element concentration is determined from the X-ray intensity value obtained by measuring an unknown sample in reference to this calibration curve.

[0038] Generally, a plurality of standard samples for the calibration curve are prepared and analyzed to create the calibration curve, and the created calibration curve is then used to quantitatively analyze the unknown sample.

[0039] However, when creating a calibration curve using multiple standard samples in an X-ray fluorescence analyzer, if the user mixes up the samples, the calibration curve will be incorrect, and the quantitative values ​​of unknown samples using that calibration curve will contain large errors.

[0040] When the sample is placed by hand, it is easy for the person performing the measurement to notice that the sample is incorrect, but when multiple samples are set on a multi-sample changer such as a turret and continuous measurements are performed, there is a risk of measuring the wrong sample due to sample misplacement.

[0041] To confirm the sample in this case, a sample observation camera can be placed on the underside of the sample, and images of the sample taken from the bottom before and after measurement can be saved. This allows the user to determine whether the sample is correct or not based on its shape, color, and other characteristics. However, in recent years, there has been a demand for higher sensitivity in X-ray fluorescence analyzers, which requires a shorter distance between the X-ray tube and the sample, making it difficult to secure the space for a sample observation camera.

[0042] In such a case, if a calibration curve is created without looking at the image and an unknown sample is measured as is, it is impossible to notice that the sample has been misplaced.

[0043] Furthermore, even if a sample image from the bottom is available, in the case of a liquid sample or a white powder sample with a different average atomic number, the sample image will be uniform, making it difficult to determine from the image whether there is a difference in the base material or content due to the misplacement of the standard sample.

[0044] In this embodiment, a fluorescent X-ray analysis apparatus that can detect an error in a sample even when there is no sample image taken by a camera or the like will be described.

[0045] First, the fluorescent X-rays of rhodium, which are the premise of this embodiment, will be described with reference to FIGS. 2 to 4 again.

[0046] The X-ray tube 7 emits excitation X-rays including rhodium fluorescent X-rays (RhKα) and continuous X-rays, as shown in FIG.

[0047] When the excitation X-rays hit the sample S and bounce back, a mixture of RhKα (Rayleigh scattering) that has not lost its energy, RhKαC (Compton scattering) in which some of the RhKα has lost energy, and fluorescent X-rays of the sample elements (not shown) are detected, as shown in Figure 4. The energy of Compton scattering is determined by the scattering angle θ with respect to the sample S. In other words, as shown in Figure 4, the difference in energy between the Rayleigh scattered X-rays and the Compton scattered X-rays is determined by θ, regardless of the base material of the sample S.

[0048] For this reason, when the target is rhodium, the energy (spectral position) of Rayleigh scattered X-rays and Compton scattered X-rays remains the same, but the peak intensity changes, regardless of the base material of the sample or the element to be identified. Since the intensity of Compton scattered X-rays differs depending on the base material, the base material can be identified by detecting a peak at a predetermined spectral position and looking at the ratio R. As shown in Figure 4, when the base material is polyethylene (PE), nylon, or polyethylene terephthalate (PET), the peak intensity of Rayleigh scattered X-rays is the same, but the peak intensity of Compton scattered X-rays differs depending on the base material.

[0049] That is, depending on the average atomic number of the sample base material, if the intensity of the Rayleigh scattered X-rays of the fluorescent X-rays of the tube target is represented by IR and the intensity of the Compton scattered X-rays is represented by IC, the ratio R (= IR / IC) between these will differ depending on the base material.

[0050] For example, if the target is Rh (rhodium), the smaller the average atomic number of the sample base material (lighter), the smaller the IR. Generally, a light element base material will have a larger IC, and a heavy element base material will have a larger IR.

[0051] Therefore, it is possible to detect if a sample with a different base material is mixed in among the placed standard samples, issue a warning before creating a calibration curve, or create a calibration curve excluding the mixed sample.

[0052] 5 is a flowchart for explaining the process of creating a calibration curve executed by the control device in embodiment 1. In step S1, the control device 14 sets a variable N indicating the standard sample number to 1. Then, in step S2, the control device 14 measures the Nth standard sample. The X-ray spectrum obtained at this time is stored in the spectrum storage unit 111.

[0053] Next, in step S3, the control device 14 causes the peak extraction unit 112 to extract the Rayleigh scattered X-ray intensity IR(N) and the Compton scattered X-ray intensity IC(N) of the fluorescent X-rays of rhodium, which is the target of the X-ray tube, from the X-ray spectrum obtained by measuring the Nth sample.

[0054] The control device 14 then calculates the intensity ratio R (=IR / IC) of the Nth standard sample in the discrimination unit 113 and determines whether the intensity ratio R is within a reference range (steps S4 and S5). Hereinafter, the reference range set for the intensity ratio R is also referred to as a first reference range.

[0055] Fig. 6 is a diagram for explaining the intensity ratio R and the first reference range. In Fig. 6, the horizontal axis indicates the standard sample number, and the vertical axis indicates the intensity ratio R. Furthermore, the intensity ratio between the intensity of the Rayleigh scattered X-rays and the intensity of the Compton scattered X-rays of the tube target in the measurement of each standard sample for the calibration curve is indicated as Rstd(n). n represents the number of the standard sample (1 to 6 in the case of six standard samples).

[0056] Assume that the intensity ratios Rstd1 to Rstd6 obtained by measurement are distributed as shown in Figure 6. Here, a first standard range of the intensity ratio R is determined in advance corresponding to the base material. The lower limit of the first standard range is indicated by RL, and the upper limit of the first standard range is indicated by RU. In the example shown in Figure 6, the standard samples with sample numbers N = 1, 2, 3, 5, and 6 exhibit intensity ratios within the first standard range, and the standard sample with sample number N = 4 exhibits an intensity ratio outside the first standard range.

[0057] In this case, a possible cause may be that sample number N=4 was mixed in due to a user error. When the intensity ratio R is determined to be within the first reference range (YES in S5), as in the case of sample numbers N=1, 2, 3, 5, and 6 in FIG. 6, the discrimination unit 113 determines in step S6 of FIG. 5 that the standard sample can be used to create a calibration curve. On the other hand, when the intensity ratio R is determined to be outside the first reference range (NO in S5), as in the case of sample number N=4 in FIG. 6, the discrimination unit 113 determines in step S7 of FIG. 5 that the standard sample cannot be used to create a calibration curve, and displays a warning to the user in step S8. For example, a warning message is displayed indicating that the placed standard sample may be misplaced. The warning display in S8 may be displayed all at once after the discrimination of samples 1 to N is complete.

[0058] After the processing of step S6 or step S8, the control device 14 determines whether the sample number N is the last number, and if it is not the last number (NO in S9), increments N by 1 in step S10 and repeats the processing from step S2 onwards. On the other hand, if the sample number N is the last number (YES in S9), the control device 14 creates a calibration curve using the standard sample that was determined to be usable in step S11.

[0059] The energy (spectral position) of fluorescent X-rays varies depending on the component to be identified, and the peak intensity varies with concentration. A calibration curve is created to derive the correspondence between intensity and concentration.

[0060] Assume that the same base material is resin A, and the target element to be identified in the unknown sample is known in the standard samples. Standard sample 1 contains resin A with Y1 (ppm) of the target component, and standard sample 2 contains resin A with Y2 (ppm) of the target component. In step S11, these X-ray intensities are measured, and a calibration curve is created by connecting multiple points expressed as (X, Y) = (intensity, concentration) on an XY plane as shown in Figure 8 using the least squares method. The peak intensities used here are those of the fluorescent X-rays of the target element, not shown in Figure 4.

[0061] In the above description, the first reference range used in step S5 is predetermined for the base material, but the first reference range may be determined during the measurement of the standard sample.

[0062] When the standard deviation of the intensity of Rayleigh scattered X-rays is σIR and the standard deviation of the intensity of Compton scattered X-rays is σIC, the standard deviation of the intensity ratio σR is derived as follows from error propagation:

[0063] When c=a / b, and the errors of a, b, and c are represented by δa, δb, and δc, respectively, the following equation (1) holds due to the propagation of errors in the case of division.

[0064]

[0065] In the above formula (1), if the standard deviations of a and b are represented by σa and σb, respectively, the following formula (2) holds for the maximum standard deviation σc of c: σc = c × (σa / a + σb / b) (2) By substituting the intensity IR of the Rayleigh scattered X-rays for a, the standard deviation σIR of the Rayleigh scattered X-ray intensity for σa, the intensity IC of the Compton scattered X-rays for b, the standard deviation σIC of the Compton scattered X-ray intensity for σb, the intensity ratio R (= IR / IC) of the Rayleigh scattered X-rays to the Compton scattered X-rays for c, and substituting the standard deviation σR of the intensity ratio R for σc, and rearranging the formula (2), the following formula (3) is obtained: σR = R × (σIR / IR + σIC / IC) (3) The standard deviation σR of the intensity ratio obtained from the standard sample measured in this manner can be used to determine the first reference range to be applied in step S5. For example, the reference range can be set to a range of Rave±n×σR (n is a number indicating the range). Rave is the average value of the intensity ratios of multiple samples, but it can also be the median value. The above-mentioned σR is just an example, and it can also be a certain threshold range centered on Rave, rather than the standard deviation.

[0066] As described above, the X-ray fluorescence analyzer of the first embodiment can detect whether a sample with a different base material is mixed in the placed standard samples, and can issue a warning before creating a calibration curve, or can create a calibration curve excluding the mixed sample.

[0067] [Embodiment 2] In the first embodiment, it is assumed that a sample with a different base material is mixed in when measuring a standard sample and creating a calibration curve. However, it is also possible that the base material of the standard sample itself is correct but the concentration of the standard sample is entered into the fluorescent X-ray device incorrectly, or that the input is correct but the order of placement is incorrect. In the second embodiment, a warning can be issued to the user in such cases. Note that the warning in the second embodiment may be issued in combination with the warning in the first embodiment.

[0068] 7 is a flowchart for explaining the calibration curve creation process executed by the control device in embodiment 2. Note that it is assumed that the measurement of the fluorescent X-ray peak intensities of the analysis target elements of the N standard samples executed in S2 of FIG. 5 has been completed before the process of FIG. 7 starts. The control device 14 then determines whether any of the N standard samples is unsuitable for creating a calibration curve.

[0069] First, in step S11, the control unit 14 sets a variable N indicating the standard sample number to 1. Then, in step S12, the control unit 14 creates a provisional calibration curve for the standard samples other than the Nth one.

[0070] In step S13, the control device 14 determines whether the N-th intensity X(N) falls within a reference range for the calibration curve. The reference range set for the calibration curve at this time is also referred to as a second reference range hereinafter.

[0071] 8 is a diagram illustrating the calibration curve and the second reference range, in which the horizontal axis represents intensity (cps / μA) and the vertical axis represents the concentration (ppm) of the analyte.

[0072] The calibration curve is calculated by the least squares method for multiple points measured using multiple standard samples with different contents of the target element for a given base material. The intensity (cps / μA) on the horizontal axis is the value obtained by dividing the number of counts per second of the detector 8 by the tube current value. The concentration (ppm) of the target component for analysis on the vertical axis is a value known in advance for each standard sample, and is entered by the user via a keyboard or a data file when creating the calibration curve.

[0073] The number of standard samples for determining a calibration curve is often six, but it can also be two. In simple cases, a calibration curve can be determined using the origin and one standard sample.

[0074] The example shown in Figure 8 is an example of a linear calibration curve. When the content of the element to be measured is low, the intensity increases in proportion to the concentration of the element, so the correlation coefficient between concentration and intensity is approximately 1. As shown by the black dots in Figure 8, when measuring standard samples with different base materials, the intensity value X differs, and so those points deviate from the straight line of the calibration curve created from the standard samples shown by the five white dots.

[0075] A second reference range is defined for the calibration curve created in step S12. In the example of Fig. 8, it is determined in step S13 whether the registered concentration Y(N) for the detected intensity X(N) is between a concentration upper limit LU and a concentration lower limit LL. The concentration upper limit LU and the concentration lower limit LL may be determined in advance in accordance with the base material, or the width from the calibration curve may be determined as a standard deviation, as described in the first embodiment.

[0076] In addition, in step S13, the registered concentration Y(N) is compared with the second reference range, but it is sufficient to determine whether the point representing the sample on the plane in Figure 8 is between the two straight lines. Therefore, in step S13, it may be determined whether the intensity X(N) is between the upper intensity limit value and the lower intensity limit value.

[0077] If the concentration Y(N) is within the reference range (YES in S13), the control device 14 determines in step S14 that the Nth standard sample can be used to create a calibration curve. On the other hand, if the concentration Y(N) is outside the second reference range (NO in S13), the control device 14 determines in step S15 that the Nth standard sample cannot be used to create a calibration curve, and displays a warning to the user in step S16.

[0078] After the processing of step S14 or step S15, the control device 14 determines whether the sample number N is the last number, and if it is not the last number (NO in S17), increments N by 1 in step S18 and repeats the processing from step S12. On the other hand, if the sample number N is the last number (YES in S17), the control device 14 creates a final calibration curve to be used in the analysis of unknown samples using the standard samples determined to be usable in step S19.

[0079] Even if multiple standard samples of the same base material are used, if a standard sample with a different content than the content set in the measurement conditions is mistakenly placed and measured, a correct calibration curve cannot be created. The X-ray fluorescence analyzer of the second embodiment can detect and warn of cases where a standard sample with a different concentration from the correct value is placed by mistake, or when the concentration of the standard sample is entered incorrectly, thereby preventing the creation of an incorrect calibration curve.

[0080] [Embodiment 3] In the first and second embodiments, a warning is issued if there is a problem with the standard sample when creating a calibration curve, but the intensity ratio R used in the first embodiment can also be applied to errors in unknown samples.

[0081] FIG. 9 is a flowchart for explaining a process of specifying a concentration using a calibration curve, which is executed by the control device in the third embodiment.

[0082] In step S21, the control device 14 measures the X-ray spectrum of an unknown sample. Then, in step S22, the control device 14 extracts the intensity IR of Rayleigh scattered X-rays and the intensity IC of Compton scattered X-rays of fluorescent X-rays from rhodium, which is the target of the X-ray tube, from the X-ray spectrum obtained by measuring the Nth sample.

[0083] The control device 14 then calculates the intensity ratio R (=IR / IC) of the unknown sample and determines whether the intensity ratio R is within the reference range corresponding to the standard sample used to create the calibration curve (steps S23, S24).

[0084] The intensity ratio obtained by measuring an unknown sample is represented by Runk(j), and the intensity ratio obtained by measuring a standard sample is represented by Rstd(n). j represents the number of the unknown sample, and n represents the number of the standard sample. Typically, the standard sample and the unknown sample are often made of the same base material (resin, metal, liquid, powder), and the values ​​of Runk(j) and Rstd(n) are expected to be approximately the same. Therefore, the reference range used in the determination of step S24 can be the same as the first reference range used in the determination of the standard sample.

[0085] If the intensity ratio R is determined to be within the first reference range (YES in S24), the control device 14 determines in step S25 that the base material of the unknown sample matches that of the standard sample, and identifies the component concentrations of the unknown sample using a calibration curve previously prepared using the standard sample in step S26. On the other hand, if the intensity ratio R is determined to be outside the first reference range (NO in S24), the control device 14 determines in step S27 that the base material of the unknown sample does not match that of the standard sample, and displays a warning to the user in step S28.

[0086] As described above, according to the X-ray fluorescence spectrometer of the third embodiment, if the base material of the unknown sample to be analyzed is different from the base material of the standard sample, a warning message is displayed to the user, so that the user can notice the mistake.

[0087] Aspects It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0088] (Section 1) A first aspect of the present disclosure relates to an X-ray fluorescence analyzer for analyzing the constituent elements of a sample. The X-ray fluorescence analyzer includes a sample stage on which a sample is placed, an X-ray tube including a target that receives thermoelectrons and emits X-rays, and configured to irradiate excitation X-rays, including fluorescent X-rays of the target material, toward the sample stage, a detector that detects the fluorescent X-rays emitted from the sample on the sample stage, and a control device that controls the X-ray tube and the detector. When a calibration curve is created by irradiating a standard sample with excitation X-rays from the X-ray tube and generating a calibration curve, the control device is configured to issue a warning if the IR / IC value obtained for the standard sample falls outside a first reference range. In this way, the X-ray fluorescence analyzer detects and notifies the user that the sample was selected inappropriately when generating the calibration curve, thereby preventing measurement errors from increasing.

[0089] (Item 2) In the fluorescent X-ray analyzer described in item 1, the first reference range is preferably a range that is predetermined for the base material of the standard sample and is stored in the control device.

[0090] (Item 3) In the X-ray fluorescence analyzer described in item 1, the sample stage is preferably provided with a plurality of openings into which samples can be placed, and the control device is configured to sequentially irradiate the plurality of standard samples placed in the respective openings with excitation X-rays from the X-ray tube to create a calibration curve.

[0091] (4) In the X-ray fluorescence analyzer described in (3), the first reference range is preferably determined based on the average value Rave and standard deviation σR of IR / IC obtained for a plurality of standard samples placed in the plurality of openings when creating the calibration curve.

[0092] (Item 5) In the X-ray fluorescence analyzer described in item 1, the control device is preferably configured to issue a warning if the IR / IC value obtained by measuring the sample after the calibration curve has been created is outside the first reference range.

[0093] (Item 6) In the X-ray fluorescence analyzer described in Item 1, the control device is preferably configured to issue a warning when, when creating a calibration curve using a plurality of standard samples, an analysis point obtained by measuring the standard sample to be evaluated and the concentration of the analyte component registered for the standard sample to be evaluated is outside a second reference range defined for the tentative calibration curve. This tentative calibration curve is a calibration curve created using the plurality of standard samples or a calibration curve created using samples excluding the standard sample to be evaluated from the plurality of standard samples.

[0094] The configurations described in the embodiments of this specification may be freely combined and used.

[0095] According to the X-ray fluorescence analyzer of this embodiment, even if a sample observation camera is not available, the user can be notified of misplaced samples and the like by analyzing the measurement data. The user can become aware of the misplaced sample without looking at an image of the sample. This improves the ease of use of the X-ray fluorescence analyzer and also improves the reliability of the measurement data.

[0096] 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 embodiments, and is intended to include all modifications within the meaning and scope of the claims.

[0097] REFERENCE SIGNS LIST 1 Sample chamber, 2 Sample stage, 3 Housing, 4, 20 Opening, 5 Measurement chamber, 6 Wall, 7 X-ray tube, 8 Detector, 9 Shutter, 10 X-ray analysis device, 11 X-ray filter, 12 Drive mechanism, 13 Collimator, 14 Control device, 15 Operation unit, 16 Output unit, 81 X-ray detector, 82 Preamplifier, 83 Proportional amplifier, 110 Data processing unit, 111 Spectrum storage unit, 112 Peak extraction unit, 113 Discrimination unit, 115 Control unit, 141 CPU, 142 Memory.

Claims

1. An X-ray fluorescence analyzer for analyzing constituent elements of a sample, comprising: A sample stage on which the sample is placed; an X-ray tube including a target that receives thermal electrons and emits X-rays, and configured to irradiate excitation X-rays including fluorescent X-rays of a material of the target toward the sample stage; a detector for detecting fluorescent X-rays emitted from the sample on the sample stage; a control device for controlling the X-ray tube and the detector, Let IR be the intensity of X-rays that are Rayleigh scattered by the sample placed on the sample stage from the fluorescent X-rays of the target material, and IC be the intensity of X-rays that are Compton scattered by the sample placed on the sample stage from the fluorescent X-rays of the target material, the control device is configured to issue a warning when a calibration curve is created by irradiating a standard sample with the excitation X-rays from the X-ray tube and an IR / IC value obtained for the standard sample is outside a first reference range; The first reference range is a range that is predetermined for a base material of the standard sample and is stored in the control device.

2. An X-ray fluorescence analyzer for analyzing the constituent elements of a sample, comprising: A sample stage on which the sample is placed; an X-ray tube including a target that receives thermal electrons and emits X-rays, and configured to irradiate excitation X-rays including fluorescent X-rays of a material of the target toward the sample stage; a detector for detecting fluorescent X-rays emitted from the sample on the sample stage; a control device for controlling the X-ray tube and the detector, Let IR be the intensity of X-rays that are Rayleigh scattered by the sample placed on the sample stage from the fluorescent X-rays of the target material, and IC be the intensity of X-rays that are Compton scattered by the sample placed on the sample stage from the fluorescent X-rays of the target material, the control device is configured to issue a warning when a calibration curve is created by irradiating a standard sample with the excitation X-rays from the X-ray tube and an IR / IC value obtained for the standard sample is outside a first reference range; the sample stage is provided with a plurality of openings in which samples can be placed; the control device is configured to sequentially irradiate a plurality of standard samples placed in the plurality of openings, respectively, with the excitation X-rays from the X-ray tube, thereby creating the calibration curve.

3. 3. The X-ray fluorescence analysis apparatus according to claim 2, wherein the first reference range is determined based on an average value and a standard deviation of IR / IC obtained for a plurality of standard samples placed in the plurality of openings, respectively, when creating the calibration curve.

4. 2. The X-ray fluorescence analysis apparatus of claim 1, wherein the control device is configured to issue a warning if the IR / IC value obtained by measuring the sample after the calibration curve is created is outside the first reference range.

5. An X-ray fluorescence analyzer for analyzing the constituent elements of a sample, comprising: A sample stage on which the sample is placed; an X-ray tube including a target that receives thermal electrons and emits X-rays, and configured to irradiate excitation X-rays including fluorescent X-rays of a material of the target toward the sample stage; a detector for detecting fluorescent X-rays emitted from the sample on the sample stage; a control device for controlling the X-ray tube and the detector, Let IR be the intensity of X-rays that are Rayleigh scattered by the sample placed on the sample stage from the fluorescent X-rays of the target material, and IC be the intensity of X-rays that are Compton scattered by the sample placed on the sample stage from the fluorescent X-rays of the target material, the control device is configured to issue a warning when a calibration curve is created by irradiating a standard sample with the excitation X-rays from the X-ray tube and an IR / IC value obtained for the standard sample is outside a first reference range; the control device is configured to issue a warning when, when creating the calibration curve using a plurality of standard samples, an analysis point obtained by measuring the standard sample to be determined and a concentration of the target component to be determined registered for the standard sample to be determined is outside a second reference range defined for the tentative calibration curve; The tentative calibration curve is a calibration curve created using the plurality of standard samples, or a calibration curve created using samples excluding the standard sample to be determined from the plurality of standard samples.