X-ray fluorescence analyzer

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

Technical Field

[0001] The present disclosure relates to a fluorescent X-ray analyzer.

Background Art

[0002] Fluorescent X-ray analysis is an analytical method for analyzing the constituent elements of a sample by irradiating the sample with X-rays and measuring the fluorescent X-rays emitted from the sample.

[0003] For example, in the fluorescent X-ray analyzer disclosed in Japanese Unexamined Patent Application Publication No. 2015-94643 (Patent Document 1), a "calibration curve" obtained by previously measuring the relationship between "element concentration D" and "fluorescent X-ray intensity I per excitation X-ray intensity Iex" using a standard sample S is used. By means of the calibration curve, the intensity of the fluorescent X-rays emitted from an unknown sample can be converted into the concentration of the detected component in the unknown sample.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] A calibration curve is created by measuring the fluorescent X-ray intensity Ia per tube current using a standard sample containing an element a with a known concentration or content (hereinafter typically referred to as concentration) Da. The number of standard samples may be 1, but in many cases, a plurality of standard samples with different concentrations Da are used.

[0006] However, when creating a calibration curve using a plurality of standard samples in a fluorescent X-ray analyzer, if the user sets a sample different from the standard sample that should be used by mistake in the apparatus, an incorrect calibration curve will result, and the quantitative value of the unknown sample using that calibration curve will include a large error. Also, when the base materials of the calibration curve and the unknown sample are different, the error in the quantitative result becomes large.

[0007] The purpose of this disclosure is to provide an X-ray fluorescence analyzer that can detect when a sample is inappropriate and suppress measurement errors when using a calibration curve. [Means for solving the problem]

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

[0009] The X-ray fluorescence analyzer described herein detects when the sample selection is inappropriate when creating a calibration curve and notifies the user, thereby preventing situations where measurement errors are amplified. [Brief explanation of the drawing]

[0010] [Figure 1] This diagram schematically shows the overall configuration of a fluorescence X-ray analyzer. [Figure 2] This is a functional block diagram of the detector 8 and the control device 14. [Figure 3] This figure shows the X-ray spectrum of the excitation X-rays emitted from the X-ray tube. [Figure 4] This figure shows the X-ray spectrum of the X-rays detected by the detector 8 after the excitation X-rays are incident on the sample S. [Figure 5]This is a flowchart illustrating the calibration curve creation process performed by the control device in Embodiment 1. [Figure 6] This is a diagram to explain the intensity ratio R and the reference range. [Figure 7] This is a flowchart illustrating the calibration curve creation process performed by the control device in Embodiment 2. [Figure 8] This is a diagram illustrating the calibration curve and its reference range. [Figure 9] This is a flowchart illustrating the concentration determination process using a calibration curve performed by the control device in Embodiment 3. [Modes for carrying out the invention]

[0011] The embodiments will be described in detail below with reference to the drawings. Note that the same or corresponding parts in the drawings are denoted by the same reference numerals, and their descriptions will not be repeated.

[0012] [Embodiment 1] Figure 1 is a schematic diagram showing the overall configuration of a fluorescent X-ray analyzer. The fluorescent X-ray analyzer 10 shown in Figure 1 comprises 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 the measurement chamber 5 are enclosed by the housing 3 to be airtight, and the interior can be kept under vacuum as needed.

[0014] The sample chamber 1 includes a sample stage 2 at the bottom on which a plurality of samples S can be placed. A plurality (for example, 12) of openings 20 for placing the sample S are formed in the sample stage 2. The sample S is placed on the sample stage 2 so as to cover the opening 20. Such a sample stage 2 can be rotated to switch the sample S to be analyzed, and is called a turret. The sample S has a front surface SA having a measurement position and a back surface SB located on the side opposite to the front surface SA. During measurement, the rotational position of the sample stage 2 is determined so that the measurement position of the front surface SA is exposed from the opening 4 at the bottom of the housing 3.

[0015] The measurement chamber 5 includes an X-ray tube 7 and a detector 8 on its wall surface 6. The X-ray tube 7 irradiates the sample S with primary X-rays. The primary X-rays emitted from the X-ray tube 7 are irradiated onto the measurement position of the sample S through the opening 4. The secondary X-rays (fluorescent X-rays) emitted by the sample S enter 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 in a direction perpendicular to the plane of the drawing of FIG. 1 by a drive mechanism 12.

[0017] The shutter 9 is formed of an X-ray absorbing material such as lead and can be inserted into the optical path of the primary X-rays to shield the primary X-rays when necessary.

[0018] The primary X-ray filter 11 is formed of a metal foil selected according to the purpose, attenuates the background component of the primary X-rays emitted from the X-ray tube 7, and improves the S / N ratio of the necessary characteristic X-rays. In an actual apparatus, a plurality of primary X-ray filters 11 formed of different types of metals 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 the drive mechanism 12.

[0019] The collimator 13 is an aperture with a circular opening in the center, which determines the size of the primary X-ray beam irradiating the sample S. The collimator 13 is made of an X-ray absorbing material such as lead or brass. In the actual apparatus, multiple collimators 13 with different aperture diameters are arranged side by side in a direction perpendicular to the plane of the paper in Figure 1, and the collimator 13 selected according to the purpose is inserted onto the primary X-ray beamline by the drive mechanism 12.

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

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

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

[0023] The output unit 16 includes a display device, for example, an LCD (Liquid Crystal Display) or an organic EL (Electro Luminescence). The display device displays an image according to the 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 from the control device 14 along with identification information (product name, part number, measurement location, etc.) for identifying the sample S.

[0024] The control device 14 comprises a CPU 141 and a memory 142 for storing programs and data. The memory 142 includes ROM (Read Only Memory), RAM (Random Access Memory), and SSD (Solid State Drive). An HDD (Hard Disk Drive) may be included instead of the SSD.

[0025] The ROM stores programs executed by the CPU 141. The RAM temporarily stores data used during program execution on 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 measurement results from the X-ray fluorescence analyzer 10.

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

[0027] The detector 8 includes an X-ray detector 81, a preamplifier 82, and a proportional amplifier 83. The control device 14 includes an analog-to-digital 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 thermionic electrons and a target T that converts the thermionic electrons into predetermined primary X-rays and emits them. The target T is made of a metal such as rhodium. The control unit 115 controls the tube voltage of the X-ray tube to adjust the X-ray intensity.

[0029] When primary X-rays (excitation X-rays) emitted from the X-ray tube 7 irradiate the sample S, secondary X-rays (including fluorescence X-rays from the sample S) excited by the primary X-rays are emitted from the sample S and incident on an X-ray detector 81, such as a silicon drift detector, where they are detected as a current signal. In addition, some of the excitation X-rays irradiated onto the sample S are scattered by the sample S, and these 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. 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 the preamplifier 82 and then to a proportional amplifier 83 including a waveform shaping circuit, where it is shaped into a pulse of an appropriate shape with a pulse height corresponding to the height of each step and output.

[0031] The analog-to-digital converter (ADC) 106 samples this pulsed analog signal at a predetermined sampling period and digitizes it. The multi-channel analyzer (MCA) 107 discriminates each pulse according to its energy level based on the pulse height of the digitized pulse signal, counts each pulse, and creates a pulse height distribution diagram, i.e., an X-ray spectrum, which is then input to the data processing unit 110. The data constituting the X-ray spectrum is stored in the spectrum storage unit 111.

[0032] Figure 3 shows the X-ray spectrum of the excitation X-rays emitted from the X-ray tube. Figure 4 shows the X-ray spectrum of the X-rays detected by the detector 8 after the excitation X-rays were incident on the sample S.

[0033] As shown in Figure 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 a peak originating from rhodium (Rh), the target element of X-ray tube 7.

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

[0035] Although not shown in Figure 4, element-specific spectral lines SKα also appear as peaks at positions corresponding to the energy values ​​of the fluorescent X-rays emitted from the elements contained in the sample S being analyzed.

[0036] In the data processing unit 110, the peak extraction unit 112 detects each peak appearing on the X-ray spectrum and extracts the peaks 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 discrimination process to determine the type of resin contained in the sample. In this embodiment, when the discrimination unit 113 creates a calibration curve and when analyzing a sample using the calibration curve, a verification process is performed for the sample placed by the user.

[0037] Here, let me explain the calibration curve method. The calibration curve method involves creating a calibration curve in advance that shows the relationship between X-ray intensity and elemental concentration (or content) from the results of measuring a standard sample, and then determining the elemental concentration from the X-ray intensity values ​​obtained by measuring an unknown sample in relation to this calibration curve.

[0038] Generally, multiple standard samples are prepared for calibration curves, and analysis of these standard samples is performed to create the calibration curve. Then, the created calibration curve is used to perform quantitative analysis of the unknown sample.

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

[0040] When samples are placed manually, the operator is more likely to notice if they are the wrong sample. However, when multiple samples are set in a multi-sample exchange machine such as a turret and continuous measurements are performed, there is a possibility of measuring the wrong sample due to incorrect placement.

[0041] In such cases, to verify the sample, it is conceivable to place a sample observation camera on the underside of the sample and photograph the sample from the bottom before and after measurement to record the sample image. Then, whether or not the sample is correct can be determined from the sample image based on its shape, color, etc. However, in recent years, there has been a demand for higher sensitivity in X-ray fluorescence analyzers, which requires bringing the X-ray tube closer to the sample, making it difficult to secure space to place a sample observation camera.

[0042] In such cases, if a calibration curve is created without viewing the image and the unknown sample is measured as is, it will be impossible to notice if the sample has been placed incorrectly.

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

[0044] This embodiment describes an X-ray fluorescence analyzer that can detect sample errors even when there are no sample images from a camera or the like.

[0045] First, the rhodium fluorescence X-ray, which is the premise of this embodiment, will be explained again with reference to Figures 2 to 4.

[0046] X-ray tube 7 emits excitation X-rays, including rhodium fluorescent X-rays (RhKα) and continuous X-rays, as shown in Figure 3.

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

[0048] Therefore, for Rayleigh scattered X-rays and Compton scattered X-rays, if the target is rhodium, the energy (spectral position) remains constant regardless of the sample's base material or the element to be identified, but the peak intensity changes. Since the intensity of Compton scattered X-rays differs depending on the base material, the base material can be identified by detecting the peak at a predetermined spectral position and examining 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] In other words, if we express the intensity of Rayleigh scattered X-rays from the fluorescent X-ray target as IR and the intensity of Compton scattered X-rays as IC, based on the average atomic number of the sample matrix, then the ratio R (=IR / IC) will differ depending on the matrix.

[0050] For example, if the target is Rh (rhodium), the IR will be smaller if the average atomic number of the sample matrix is ​​small (light). Generally, light element matrix materials result in a larger IC, while heavy element matrix materials result in a larger IR.

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

[0052] Figure 5 is a flowchart illustrating the calibration curve creation process performed by the control device in Embodiment 1. In step S1, the control device 14 sets the variable N, which indicates 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 extracts the intensity IR(N) of Rayleigh scattered X-rays and the intensity IC(N) of Compton scattered X-rays from the rhodium fluorescence X-rays, which are the target of the X-ray tube, from the X-ray spectrum obtained by measuring the Nth sample in the peak extraction unit 112.

[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 the reference range (steps S4, S5). Hereinafter, the reference range set for the intensity ratio R will also be called the first reference range.

[0055] Figure 6 is a diagram illustrating the intensity ratio R and the first reference range. In Figure 6, the horizontal axis shows the standard sample number, and the vertical axis shows the intensity ratio R. Furthermore, Rstd(n) shows the intensity ratio of the Rayleigh scattered X-ray intensity to the Compton scattered X-ray intensity at the tube target for each standard sample used in the calibration curve. n represents the standard sample number (1 to 6 if there are 6 standard samples).

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

[0057] In this case, possible causes include sample number N=4 being accidentally included due to user error. If the intensity ratio R is determined to be within the first reference range, as in Figure 6, sample numbers N=1, 2, 3, 5, 6 (YES in S5), the discrimination unit 113 determines in step S6 of Figure 5 that the standard sample can be used to create a calibration curve. On the other hand, if the intensity ratio R is determined to be outside the first reference range, as in Figure 6, sample number N=4 (NO in S5), the discrimination unit 113 determines in step S7 of Figure 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, it displays a warning message indicating that the placed standard sample may be the wrong sample. Note that 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 in step S6 or step S8, the control device 14 determines whether sample number N is the last number. If it is not the last number (NO in S9), in step S10, it adds 1 to N and repeats the processing from step S2. On the other hand, if sample number N is the last number (YES in S9), the control device 14 creates a calibration curve in step S11 using the standard sample that was determined to be usable.

[0059] The energy (and thus the position in the spectrum) of fluorescent X-rays varies depending on the component to be identified, and the peak intensity changes with concentration. Calibration curves are created to derive the correspondence between intensity and concentration.

[0060] Let's say the same base material is resin A, and the target element to be identified in the unknown sample is known in the standard sample. Then, standard sample 1 contains resin A with Y1 (ppm) of the target element, and standard sample 2 contains resin A with Y2 (ppm) of the target element. In step S11, the X-ray intensities of these samples are measured, and a calibration curve is created by connecting multiple points represented by (X,Y)=(intensity, concentration) on the XY plane as shown in Figure 8 using the least squares method. The peak intensity used at this time is the peak intensity of the fluorescent X-ray of the target element, which is not shown in Figure 4.

[0061] In the above explanation, we described the case where the first reference range used in step S5 is predetermined for the base material, but the first reference range may also be determined during the process of measuring the standard sample.

[0062] If σIR is the standard deviation of the intensity of Rayleigh-scattered X-rays and σIC is the standard deviation of the intensity of Compton-scattered X-rays, then the standard deviation of the intensity ratio σR can be derived from the propagation of errors as follows.

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

[0064]

number

[0065] In equation (1) above, if we express the standard deviations of a and b as σa and σb, respectively, then the following equation (2) holds for the largest standard deviation of c, σc. σc = c × (σa / a + σb / b) ... (2) By substituting the intensity IR of Rayleigh-scattered X-rays into a, the standard deviation σIR of the intensity of Rayleigh-scattered X-rays into σa, the intensity IC of Compton-scattered X-rays into b, the standard deviation σIC of the intensity of Compton-scattered X-rays into σb, the intensity ratio R (=IR / IC) of Rayleigh-scattered X-rays to Compton-scattered X-rays into c, and the standard deviation σR of the intensity ratio R into σc, we obtain the following equation (3). σR=R×(σIR / IR+σIC / IC)…(3) The first reference range to be applied in step S5 can be determined using the standard deviation σR of the intensity ratio obtained from the standard sample measured in this way. For example, the reference range can be set to the range of Rave ± n × σR (where n is a numerical value indicating the width). Rave is the average value of the intensity ratios of multiple samples, but the median or other values ​​may also be used. The above σR is just an example; instead of the standard deviation, a threshold range centered on Rave may also be used.

[0066] As described above, the X-ray fluorescence analyzer of Embodiment 1 can detect if a sample with a different base material is mixed in with the placed standard samples, and can issue a warning before creating a calibration curve, or create a calibration curve after excluding the mixed sample.

[0067] [Embodiment 2] In Embodiment 1, when measuring a standard sample and creating a calibration curve, the case was assumed in which samples with different base materials were mixed in. However, even if the base material of the standard sample itself is correct, the concentration of the standard sample is incorrect, and the X-ray fluorescence analysis Even if the input is correct, the arrangement order may be incorrect. In Embodiment 2, the user can be warned in such cases. The warning in Embodiment 2 may be given in combination with the warning in Embodiment 1.

[0068] Figure 7 is a flowchart illustrating the calibration curve creation process performed by the control device in Embodiment 2. It is assumed that, prior to the start of the process in Figure 7, the measurement of the peak intensity of the analyte X-rays of the N standard samples, performed in S2 of Figure 5, has been completed. The control device 14 then determines whether any of the N standard samples are unsuitable for creating the calibration curve.

[0069] First, in step S11, the control device 14 sets the variable N, which indicates the standard sample number in step S11, to 1. Then, in step S12, the control device 14 creates a provisional calibration curve using standard samples other than the Nth standard.

[0070] Then, in step S13, the control device 14 determines whether the Nth intensity X(N) falls within the reference range relative to the calibration curve. At this time, the reference range set relative to the calibration curve will also be referred to as the second reference range.

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

[0072] The calibration curve is calculated using the least squares method for multiple points obtained by measuring several standard samples with varying concentrations of the analyte element against a given base material. The intensity on the horizontal axis (cps / μA) is the value obtained by dividing the detector count per second by the tube current value. The concentration of the analyte component (ppm) on the vertical axis is a value known in advance for each standard sample, and is entered by the user from a keyboard or data file when creating the calibration curve.

[0073] The number of standard samples used to define a calibration curve is often six, but two is also acceptable. In simpler cases, the calibration curve may be defined using the origin and a single standard sample point.

[0074] The example shown in Figure 8 is an example of a linear calibration curve. When the content of the element being 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 made from different base materials, the intensity value X is different, so that point deviates 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 in Figure 8, step S13 determines whether the registered concentration Y(N) is between the upper limit LU and the lower limit LL for the detected intensity X(N). The upper limit LU and the lower limit LL may be predetermined in correspondence with the base material, or they may be defined by the standard deviation of the range from the calibration curve, as described in Embodiment 1.

[0076] Furthermore, in step S13, the registered concentration Y(N) was compared with the second reference range, but it is sufficient to determine whether the point representing the sample on the plane in Figure 8 lies between the two straight lines. Therefore, in step S13, it is also acceptable to determine whether the intensity X(N) lies between the upper and lower limits of intensity.

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

[0079] Even with multiple standard samples of the same base material, if a measurement is performed using a standard sample with a different content than that pre-set in the measurement conditions, and a calibration curve is created, an incorrect calibration curve cannot be created. The X-ray fluorescence analyzer of Embodiment 2 can detect and warn of cases where a standard sample with a different concentration than the original value is used, as well as errors in inputting the concentration of the standard sample, thus preventing the creation of an incorrect calibration curve.

[0080] [Embodiment 3] In Embodiments 1 and 2, a warning was issued if there was a problem with the standard sample when creating the calibration curve. However, the intensity ratio R used in Embodiment 1 can also be applied to errors in unknown samples.

[0081] Figure 9 is a flowchart illustrating the concentration determination process using a calibration curve performed by the control device in Embodiment 3.

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

[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 from measuring the unknown sample is represented by Runk(j), and the intensity ratio obtained from measuring the 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 in 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 in step S26, it identifies the component concentration of the unknown sample using a calibration curve previously created using the standard sample. 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 in step S28, it displays a warning to the user.

[0086] As described above, the fluorescent X-ray of Embodiment 3 analysis According to the device, if the base material of the unknown sample being analyzed differs from the base material of the standard sample, a warning message is displayed to the user, allowing the user to notice the mistake.

[0087] [Pattern] Those skilled in the art will understand that the exemplary embodiments described above are specific examples of the following embodiments.

[0088] (Section 1) A first aspect of this disclosure relates to an X-ray fluorescence analyzer for analyzing the constituent elements of a sample. The X-ray fluorescence analyzer comprises a sample stage on which a sample is placed, an X-ray tube including a target that receives thermionic electrons and emits X-rays, and configured to irradiate the sample stage with excitation X-rays including the fluorescent X-rays of the target material, a detector for detecting the fluorescent X-rays emitted from the sample on the sample stage, and a control device for controlling the X-ray tube and the detector. When the intensity of X-rays scattered by Rayleigh from the sample on the sample stage is defined as IR, and the intensity of X-rays scattered by Compton from the sample on the sample stage is defined as IC, the control device is configured to issue a warning when creating a calibration curve by irradiating a standard sample with excitation X-rays from the X-ray tube and the obtained IR / IC value for the standard sample is outside a first reference range. In this way, the X-ray fluorescence analyzer can detect if the sample selection is inappropriate when creating a calibration curve and notify the user, thereby avoiding a situation in which measurement errors are amplified.

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

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

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

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

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

[0094] Furthermore, the configurations described in each embodiment of this specification may be used in any combination.

[0095] According to the X-ray fluorescence analyzer of this embodiment, even without a sample observation camera, the user can be notified of incorrect sample placement, etc., by analyzing the measurement data. The user can notice the incorrect placement without having to view the sample image. Therefore, the ease of use of the X-ray fluorescence analyzer is improved, as is the reliability of the measurement data.

[0096] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of this disclosure is indicated by the claims rather than by the description of the embodiments above, and all modifications within the meaning and scope of the claims are intended to be included. [Explanation of symbols]

[0097] 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 fluorescence X-ray analyzer, 11 primaryX-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. A fluorescence X-ray analyzer for analyzing the constituent elements of a sample, A sample stand on which the aforementioned sample is placed, An X-ray tube comprising a target that receives thermionic electrons and emits X-rays, and configured to irradiate the sample stage with excitation X-rays including fluorescent X-rays of the target material, A detector for detecting fluorescent X-rays emitted from the sample on the sample stage, as well as Rayleigh-scattered X-rays and Compton-scattered X-rays, The system comprises a control device for controlling the X-ray tube and the detector, When the intensity of X-rays scattered by the sample placed on the sample stage from the fluorescent X-rays of the target material is defined as IR, and the intensity of X-rays scattered by the sample placed on the sample stage from the fluorescent X-rays of the target material from the sample stage is defined as IC, The control device is configured to issue a warning if, when creating a calibration curve by irradiating a standard sample with the excitation X-rays from the X-ray tube, the IR / IC value obtained for the standard sample is outside the first reference range. The first reference range is a predetermined range for the base material of the standard sample, and is stored in the control device of the X-ray fluorescence analyzer.

2. The X-ray fluorescence analyzer according to claim 1, wherein the control device is configured to create the calibration curve using standard samples that were not subject to warning, rather than using standard samples that were subject to warning.

3. A fluorescence X-ray analyzer for analyzing the constituent elements of a sample, A sample stand on which the aforementioned sample is placed, An X-ray tube comprising a target that receives thermionic electrons and emits X-rays, and configured to irradiate the sample stage with excitation X-rays including fluorescent X-rays of the target material, A detector for detecting fluorescent X-rays emitted from the sample on the sample stage, as well as Rayleigh-scattered X-rays and Compton-scattered X-rays, The system comprises a control device for controlling the X-ray tube and the detector, When the intensity of X-rays scattered by the sample placed on the sample stage from the fluorescent X-rays of the target material is defined as IR, and the intensity of X-rays scattered by the sample placed on the sample stage from the fluorescent X-rays of the target material from the sample stage is defined as IC, The control device is configured to issue a warning if, when creating a calibration curve by irradiating a standard sample with the excitation X-rays from the X-ray tube, the IR / IC value obtained for the standard sample is outside the first reference range. The sample stage is provided with multiple openings into which a sample can be placed. The control device is configured to sequentially irradiate a plurality of standard samples, each of which is placed in one of the plurality of openings, with the excitation X-rays from the X-ray tube to create the calibration curve, in an X-ray fluorescence analyzer.

4. The X-ray fluorescence analyzer according to claim 3, wherein the first reference range is determined based on the mean and standard deviation of IR / IC obtained for a plurality of standard samples placed in each of the plurality of apertures when creating the calibration curve.

5. The X-ray fluorescence analyzer according to 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 has been created is outside the first reference range.

6. A fluorescence X-ray analyzer for analyzing the constituent elements of a sample, A sample stand on which the aforementioned sample is placed, An X-ray tube comprising a target that receives thermionic electrons and emits X-rays, and configured to irradiate the sample stage with excitation X-rays including fluorescent X-rays of the target material, A detector for detecting fluorescent X-rays emitted from the sample on the sample stage, as well as Rayleigh-scattered X-rays and Compton-scattered X-rays, The system comprises a control device for controlling the X-ray tube and the detector, When the intensity of X-rays scattered by the sample placed on the sample stage from the fluorescent X-rays of the target material is defined as IR, and the intensity of X-rays scattered by the sample placed on the sample stage from the fluorescent X-rays of the target material from the sample stage is defined as IC, The control device is configured to issue a warning if, when creating a calibration curve by irradiating a standard sample with the excitation X-rays from the X-ray tube, the IR / IC value obtained for the standard sample is outside the first reference range. The control device is configured to issue a warning when, in creating the calibration curve using multiple standard samples, the analytical point obtained by measuring the X-ray fluorescence intensity of the analyte obtained from the standard sample to be determined and the concentration of the analyte registered for the standard sample to be determined falls outside the second reference range defined for the provisional calibration curve. The aforementioned provisional calibration curve is a calibration curve created using the plurality of standard samples, or a calibration curve created using the plurality of standard samples excluding the standard sample to be determined, in an X-ray fluorescence analyzer.

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