X-ray fluorescence analyzer

Abstract

In this X-ray fluorescence analyzer, when a quantification mechanism is automatically set, the overlap correction coefficient is limited to a negative value, and when a standard sample does not contain a component capable of exciting an analysis line, the absorption excitation correction coefficients of all correction components are limited to a positive value. A theoretical intensity of fluorescent X-rays to be generated by a plurality of samples composed of assumptions is calculated, theoretical matrix correction coefficients are calculated on the basis of the theoretical intensity, and a positive value is set as an upper limit value of the absorption excitation correction coefficient for a value of a predetermined multiple of each theoretical matrix correction coefficient. A negative value is set as a lower limit value of the absorption excitation correction coefficient to perform multiple regression calculation.

Description

[0001] Related Application

[0002] This application claims the benefit of Japanese Patent Application No. 2023-027360, filed on February 24, 2023, the entirety of which is hereby incorporated by reference into this application. Technical Field

[0003] The present invention relates to a fluorescent X-ray analyzer that irradiates a sample with X-rays once and, based on the measured intensity of the generated fluorescent X-rays, determines the content of a component in the sample using a calibration curve method for performing absorption excitation correction and overlap correction, or a quantitative mechanism using a fundamental parameter method including overlap correction. Background Art

[0004] Conventionally, fluorescent X-ray analyzers for quantitative analysis have been broadly divided into types based on the calibration curve method and those based on the fundamental parameter method (also known as the FP method). In quantitative analysis based on the calibration curve method, a set of standard samples with known component contents (also known as concentration ratios) is used to analyze an unknown sample. The calibration curve is then calculated by correlating the component contents with the measured intensity of the fluorescent X-rays (measurement lines) of the measurement elements corresponding to the components. A component refers to an element or a compound. Furthermore, when a component is an element, the element itself is the measurement element corresponding to the component; when a component is a compound, the element representing the compound is the measurement element corresponding to the component (for example, see paragraph 0002 of Patent Document 1).

[0005] In quantitative analysis based on the calibration curve method, in addition to background correction related to background, absorption excitation correction related to absorption excitation caused by coexisting elements (also called matrix correction) and overlap correction related to overlap of interference lines are also performed (for example, see paragraph 0003 of Patent Document 1 for absorption excitation correction). Therefore, when preparing a calibration curve represented by, for example, the following formula (1), the absorption excitation correction coefficient and the overlap correction coefficient are calculated together with the calibration curve constant through multiple regression calculation based on the measured intensity of the standard sample and the content of the known component to ensure good accuracy of the calibration curve (for accuracy, see, for example, paragraphs 0006 to 0014 of Patent Document 1).

[0006] W i =(AI i 3 +BI i 2 +CI i +D)(1+Σ j M ij I j )+Σ j O ij Ij …(1)W i :content

[0007] I: Measurement intensity

[0008] A, B, C, D: calibration curve constants

[0009] i: Analytical ingredients

[0010] j: Absorption excitation correction component or overlap correction component

[0011] M ij : Correction coefficient of absorption excitation of component j on component i

[0012] O ij : Overlap correction coefficient of component j on component i.

[0013] On the other hand, quantitative analysis using the FP method calculates the theoretical intensity of fluorescent X-rays generated by each component in the sample based on the assumed content of each component. This theoretical intensity is then approximated and corrected to match the measured intensity, converted to a theoretical intensity scale, measured by the detection mechanism, to calculate the component content in the sample. To analyze unknown samples, a set of standard samples with known component contents is required. The device sensitivity curve is then calculated by correlating the theoretical intensities calculated based on the known contents with the measured intensities (see, for example, paragraph 0003 and FIG. 4 of Patent Document 2, and paragraph 0009 of Patent Document 1).

[0014] In quantitative analysis based on the FP method, absorption and excitation corrections are generally performed for all components. Furthermore, as needed, depending on the component, an overlap correction is also performed in the device sensitivity curve represented by the following formula (2) (for details on absorption and excitation corrections, see, for example, paragraphs 0069 to 0074 of Patent Document 2). Therefore, when creating the device sensitivity curve, the overlap correction coefficient is calculated using multiple regression calculations based on the measured intensity of the standard sample and the theoretical intensity of the known component content, along with the device sensitivity constant, to ensure good accuracy of the device sensitivity curve.

[0015] I Ti =aI i 3 +bI i 2 +cI i +d+Σ j o ij I j …(2)I T : Theoretical strength

[0016] I: Determination of intensity

[0017] a, b, c, d: device sensitivity constants

[0018] i: Analytical ingredients

[0019] j: overlap correction component

[0020] o ij : Overlap correction coefficient of component j on component i

[0021] [Prior art literature]

[0022] [Patent Document]

[0023] Patent Document 1: Japanese Patent Application Laid-Open No. 2021-51053

[0024] Patent Document 2: International Publication No. 2018 / 168939

[0025] Patent Document 3: Japanese Patent Application Laid-Open No. 2000-36765 Summary of the Invention

[0026] [Problems to be solved by the invention]

[0027] However, if correction coefficients are calculated using multiple regression calculations without specific restrictions to ensure good accuracy of the calibration curve or device sensitivity curve, for example, improper sample handling in the standard sample may result in an overlap correction coefficient (a positive overlap correction coefficient) that is physically impossible and causes the overlap intensity of the interference line to become negative. Using such a calibration curve or device sensitivity curve obviously makes it impossible to perform accurate analysis.

[0028] The present invention has been proposed in response to the above-mentioned problems of the prior art, and its object is to provide a fluorescence X-ray analyzer in which the content of a component in a sample is determined using a quantitative mechanism using a calibration curve method for performing absorption-excitation correction and overlap correction, or a fundamental parameter method including overlap correction. This prevents the determination of physically impossible correction coefficients when determining correction coefficients using multiple regression calculations.

[0029] [Solutions to solve the problem]

[0030] To achieve the above-mentioned objectives, a first technical solution of the present invention is a fluorescent X-ray analyzer. This fluorescent X-ray analyzer first irradiates a sample with X-rays once, and then, based on the measured intensity of the generated fluorescent X-rays, determines the content of the component in the sample using a quantification mechanism using a calibration curve method that performs absorption-excitation correction and overlap correction. Furthermore, when the quantification mechanism uses a multiple regression calculation to determine the calibration curve constant, absorption-excitation correction coefficient, and overlap correction coefficient based on the measured intensity of a standard sample and the content of known components, it is possible to select whether to restrict the overlap correction coefficient to negative values ​​and whether to restrict the absorption-excitation correction coefficients of all correction components to positive values ​​when performing the multiple regression calculation.

[0031] On the other hand, when the quantitative mechanism is automatically set, the overlap correction coefficient is limited to a negative value. When the standard sample does not contain a component that can excite the analysis line, the absorption excitation correction coefficients of all correction components are limited to positive values, and the theoretical intensity of fluorescent X-rays that should be generated by multiple samples of the assumed composition is calculated. Based on the theoretical intensity, the theoretical matrix correction coefficient is calculated, and the value of the specified multiple of each theoretical matrix correction coefficient is set as the upper limit value of the absorption excitation correction coefficient for positive values ​​and the lower limit value of the absorption excitation correction coefficient for negative values, so as to perform multiple regression calculations.

[0032] According to the fluorescent X-ray analyzer of the first aspect, the quantification unit determines the correction coefficient by multiple regression calculation by appropriately setting constraints, thereby preventing physically impossible correction coefficients from being determined.

[0033] A second aspect of the present invention provides a fluorescent X-ray analyzer that first irradiates a sample with X-rays once and, based on the measured intensity of the generated fluorescent X-rays, determines the content of a component in the sample using a quantification mechanism using a fundamental parameter method that includes overlap correction. Furthermore, when the quantification mechanism calculates the device sensitivity constant and overlap correction coefficient using a multiple regression calculation based on the measured intensity of a standard sample and the content of a known component, the multiple regression calculation can be performed with the overlap correction coefficient constrained to negative values ​​(in manual settings). In automatic settings, the overlap correction coefficient is constrained to negative values ​​(in automatic settings).

[0034] According to the fluorescent X-ray analyzer of the second aspect, the quantification unit also determines the correction coefficient by multiple regression calculation by appropriately setting constraints, thereby preventing physically impossible correction coefficients from being determined.

[0035] The present invention also includes any combination of at least two configurations disclosed in the claims and / or the description and / or the drawings. In particular, the present invention includes any combination of two or more claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention can be more clearly understood by referring to the following description of preferred embodiments shown in the accompanying drawings. However, the embodiments and the accompanying drawings are for illustration and description only and should not be used to limit the scope of the present invention. The scope of the present invention is determined by the claims. In the accompanying drawings, the same component numbers in multiple figures represent the same parts.

[0037] Figure 1 This is a schematic diagram showing a fluorescent X-ray analyzer according to one embodiment of the present invention. DETAILED DESCRIPTION

[0038] Hereinafter, a fluorescent X-ray analysis device according to an embodiment of the present invention will be described. Figure 1 As shown, the fluorescent X-ray analyzer of this embodiment is a scanning-type fluorescent X-ray analyzer that measures the intensity of secondary X-rays 5 generated by irradiating samples 1 and 14 (including both unknown samples 1 and standard samples 14) with primary X-rays 3. The analyzer comprises: a sample stage 2 for placing the samples 1 and 14; an X-ray source 4, such as an X-ray tube, for irradiating the samples 1 and 14 with primary X-rays 3; a spectrometer 6 for spectroscopically splitting secondary X-rays 5, such as fluorescent X-rays, emitted by the samples 1 and 14; and a detector 8 for receiving the secondary X-rays 7 separated by the spectrometer 6 and detecting their intensity. The output of the detector 8 is input to a control unit 11, such as a computer, that controls the entire apparatus, via an amplifier, a wave height analyzer, a counter, and other components (not shown).

[0039] The X-ray fluorescence analyzer of this embodiment is a wavelength-dispersive, scanning-type X-ray fluorescence analyzer. It includes a linkage mechanism 10, a so-called goniometer, that links the spectroscopic element 6 and the detector 8 to change the wavelength of the secondary X-rays 7 incident on the detector 8. When the secondary X-rays 5 strike the spectroscopic element 6 at a certain incident angle θ, an extension 9 of the secondary X-rays 5 forms a splitting angle 2θ with the secondary X-rays 7 split (diffracted) by the spectroscopic element 6, which is twice the incident angle θ. To change the wavelength of the split secondary X-rays 7 by changing the splitting angle 2θ, the linkage mechanism 10 rotates the spectroscopic element 6 about an axis O, perpendicular to the paper, passing through the center of the spectroscopic element's surface, and rotates the detector 8 about the axis O along a circle 12 by twice the rotation angle. The value of the splitting angle 2θ (the 2θ angle) is input from the linkage mechanism 10 to a control mechanism 11. Furthermore, in the present invention, the X-ray fluorescence analyzer may be a wavelength dispersive and multi-element simultaneous analysis type X-ray fluorescence analyzer, or an energy dispersive X-ray fluorescence analyzer.

[0040] In the fluorescent X-ray analyzer of this embodiment, as a program installed in the control unit 11, there is a quantification unit 13. The quantification unit 13 uses a calibration curve method that performs absorption excitation correction and overlap correction based on the measured intensity of the fluorescent X-ray 5 to determine the content of each component in the samples 1 and 14. The quantification unit 13 calculates the calibration curve constants A, B, C, D and the absorption excitation correction coefficient M in the above formula (1) by multiple regression calculation based on the measured intensity of the standard sample 14 and the content of the known components. ij and overlap correction factor O ij When manually setting, you can choose whether to set the overlap correction coefficient to ij Limit to negative values, you can choose whether to use the absorption excitation correction coefficient M for all correction components j ij Restrict to positive values ​​for multiple regression calculations.

[0041] In manual setting, for example, a display 15 such as a liquid crystal display connected to the control unit 11 displays "Allow positive overlap correction" together with a check box. If the operator selects the check box using an input device such as a mouse (not shown), it indicates that the overlap correction coefficient 0 is not set. ij However, in the default state where the check box is not checked, the overlap correction factor is selected. ij Limit to negative values.

[0042] In addition, the display 15 displays "Only absorption correction is allowed" together with a check box. If the operator checks the check box using the input mechanism, it indicates that the absorption excitation correction coefficient M of all correction components j is selected. ijThe limit is a positive value, but in the default state where the check box is not checked, it means that such a limit is not selected and the excitation correction is allowed. Moreover, the quantitative unit 13 performs multiple regression calculations based on the limits corresponding to these selections. By checking the check box, you can choose not to use the overlap correction coefficient O ij Restricted to negative values, and can choose to all correction components j absorption excitation correction coefficient M ij The reason for limiting the value to a positive value is that existing users of fluorescent X-ray analysis devices may also need to perform this type of analysis.

[0043] On the other hand, the quantitative mechanism 13 sets the overlap correction coefficient 0 to 0 when the setting is automatic. ij Limit to negative values. When the standard sample 14 does not contain a component that can excite the analytical line, the absorption excitation correction coefficient M of all correction components j is set to ij The theoretical intensity of fluorescent X-rays that should be generated by multiple samples of the assumed composition is limited to positive values, and the theoretical matrix correction coefficient is calculated based on the theoretical intensity. The value of the specified multiple of each theoretical matrix correction coefficient is set as the absorption excitation correction coefficient M for positive values. ij The upper limit of the negative value is set as the absorption excitation correction coefficient M ij to perform multiple regression calculations.

[0044] For example, the display 15 displays the content "Automatically set variable upper and lower limits" together with a check box. If the operator uses the input mechanism to check the check box, it will be automatically set, and the quantitative mechanism 13 will overlap the correction coefficient O. ij Limit to negative values.

[0045] About the Absorption Excitation Correction Factor M ij The quantitative unit 13 first refers to a pre-stored library file related to the mutual absorption and excitation of elements. If the standard sample 14 does not contain a component that can excite the analytical line, all correction components j are limited to positive values. Then, similar to the known semi-fundamental parameter method, the theoretical intensity of fluorescent X-rays that should be generated by multiple samples of the assumed composition is calculated, and the theoretical matrix correction coefficient is calculated based on this theoretical intensity. In addition, for each theoretical matrix correction coefficient, a positive value is set as the absorption and excitation correction coefficient M for a predetermined multiple, such as 10 times. ij The upper limit value of the absorption excitation correction coefficient M is set to a negative value. ij to perform multiple regression calculations.

[0046] According to the fluorescent X-ray analyzer of this embodiment, the quantitative mechanism 13 sets the limit appropriately and calculates the overlap correction coefficient O by multiple regression calculation. ij and the absorption excitation correction factor M ijThis can prevent the determination of physically impossible correction coefficients, such as an overlap correction coefficient with a negative overlap intensity of an interference line (a positive overlap correction coefficient), or an absorption excitation correction coefficient that produces an analytical line that should not be excited.

[0047] The quantitative mechanism 13 of the fluorescent X-ray analyzer of this embodiment can use the basic parameter method including overlap correction to determine the content of the components in the samples 1 and 14. In this case, the quantitative mechanism 13 calculates the device sensitivity constants a, b, c, d and the overlap correction coefficient θ in the above formula (2) by multiple regression calculation based on the measured intensity of the standard sample 14 and the content of the known components. ij When manually setting, select whether to set the overlap correction coefficient o ij Restrict to negative values ​​and perform multiple regression calculations.

[0048] In manual setting, for example, the display 15 displays "Allow positive overlap correction" together with a check box. If the operator selects the check box using an input device such as a mouse (not shown), it indicates that the overlap correction coefficient o is not set. ij is limited to negative values; however, in the default state where the check box is not checked, the correction factor o is selected. ij Limit to negative values.

[0049] On the other hand, when the quantitative mechanism 13 is set automatically, the overlap correction coefficient is limited to a negative value and multiple regression calculation is performed. For example, the display 15 displays the content "Automatically set upper and lower limits of variables" together with a check box. If the operator uses the input mechanism to check the check box, the setting is automatically performed and the quantitative mechanism 13 sets the overlap correction coefficient to a negative value. ij Restrict to negative values ​​and perform multiple regression calculations.

[0050] According to the fluorescent X-ray analyzer of this embodiment, when the quantification mechanism 13 adopts the basic parameter method including overlap correction, the quantification mechanism 13 sets appropriate limits and calculates the overlap correction coefficient θ by multiple regression calculation. ij , thereby preventing the overlap correction coefficient (positive overlap correction coefficient) from being obtained when the overlap intensity of the interference line is a negative value, which is physically impossible.

[0051] As described above, the preferred embodiments have been described with reference to the accompanying drawings. However, those skilled in the art will readily conceive of various changes and modifications within the obvious scope after reading this specification. Therefore, such changes and modifications should be interpreted as still within the scope of the present invention as defined by the claims.

[0052] [Explanation of symbols]

[0053] 1, 14: Sample

[0054] 3: One X-ray

[0055] 5: Fluorescent X-ray

[0056] 13: Quantitative institutions

[0057] 15: Display.

Claims

1. A fluorescent X-ray analyzer, wherein a sample is irradiated with X-rays once, and the content of a component in the sample is determined based on the measured intensity of the generated fluorescent X-rays by a quantitative mechanism using a calibration curve method for performing absorption excitation correction and overlap correction, wherein: The quantitative mechanism performs the following operations: When the calibration curve constant, absorption excitation correction factor and overlap correction factor are calculated by multiple regression calculation based on the measured intensity of the standard sample and the content of the known components, In the case of manual setting, you can choose whether to limit the overlap correction coefficient to negative values, and whether to limit the absorption excitation correction coefficients of all correction components to positive values ​​for multiple regression calculations. In the case of automatic setting, the overlap correction coefficient is limited to a negative value. When the standard sample does not contain a component that can excite the analytical line, the absorption excitation correction coefficients of all correction components are limited to positive values. The theoretical intensity of fluorescent X-rays that should be generated by multiple samples of the assumed composition is calculated. Based on the theoretical intensity, the theoretical matrix correction coefficient is calculated. The value of each theoretical matrix correction coefficient times the specified value is set as the upper limit of the absorption excitation correction coefficient for positive values ​​and the lower limit of the absorption excitation correction coefficient for negative values ​​to perform multiple regression calculations.

2. A fluorescent X-ray analyzer that irradiates a sample with X-rays once and determines the content of a component in the sample using a quantitative mechanism using a fundamental parameter method including overlap correction based on the measured intensity of the generated fluorescent X-rays, wherein: The quantitative mechanism performs the following operations: When the device sensitivity constant and overlap correction coefficient are calculated by multiple regression calculation based on the measured intensity of the standard sample and the content of the known components, In the case of manual setting, you can choose whether to limit the overlap correction coefficient to negative values ​​for multiple regression calculations. With the automatic setting, the overlap correction coefficient is constrained to negative values ​​for multiple regression calculations.

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