Fluorescent x-ray analysis device

Abstract

In the fluorescent X-ray analysis device of the present application, the quantification mechanism calculates the lower limit of detection based on a calibration curve formula including an absorption excitation correction term and an overlap correction term.

Description

[0001] Related applications

[0002] This application claims priority to Japanese Patent Application No. 2023-027358, filed on February 24, 2023, which is incorporated herein by reference in its entirety. Technical Field

[0003] This invention relates to a fluorescence X-ray analysis apparatus in which a sample is irradiated with X-rays once, and the content of a component in the sample is determined by a quantitative mechanism using a calibration curve method for absorption excitation correction and overlap correction based on the measured intensity of the generated fluorescence X-rays. Background Technology

[0004] Traditionally, fluorescence X-ray analysis devices for quantitative analysis have been broadly categorized into two types: those based on calibration curves and those based on fundamental parameters (also known as FP methods). In quantitative analysis based on calibration curves, a set of standard samples with known component content is used to analyze unknown samples. The calibration curve is derived by analyzing the correlation between the component content and the intensity of the fluorescence X-rays (measurement line) of the corresponding analyte. Furthermore, a component refers to either an element or a compound. When the component is an element, that element itself is the corresponding analyte; when the component is a compound, the element representing that compound is the corresponding analyte.

[0005] In quantitative analysis based on calibration curves, in addition to background correction related to the background, absorption excitation correction related to absorption excitation caused by coexisting elements and overlap correction related to the overlap of interference lines are also performed. Furthermore, as one of the indicators for evaluating the performance of the prepared calibration curve, it is sometimes necessary to determine the so-called lower limit of detection. The lower limit of detection is a function of background intensity and measurement time. For example, in the fluorescence X-ray analysis apparatus described in Patent Document 1, even if the background intensity changes with the sample due to the influence of coexisting elements, the lower limit of detection is kept constant by varying the measurement time.

[0006] [Existing Technical Documents]

[0007] [Patent Literature]

[0008] Patent Document 1: Japanese Patent Application Publication No. 2006-132945 Summary of the Invention

[0009] [The problem the invention aims to solve]

[0010] However, while the fluorescence X-ray analysis apparatus described in Patent Document 1 addresses the variation of background intensity with the sample due to the influence of coexisting elements, it does not consider the absorption excitation correction related to absorption excitation, the overlap correction related to the overlap of interference lines caused by coexisting elements in the sample, and the influence of these factors on the detection limit. Furthermore, the prior art literature did not originally mention how to calculate the detection limit in the calibration curve method for absorption excitation correction and overlap correction.

[0011] The present invention addresses the problems of the prior art described above, and aims to provide a fluorescence X-ray analysis device in which the content of components in the sample is determined by a quantitative mechanism using a calibration curve method for absorption excitation correction and overlap correction, thereby enabling appropriate calculation of the detection limit.

[0012] [Solutions for solving the problem]

[0013] To achieve the above objectives, the present invention provides a fluorescence X-ray analysis device. In this device, 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 fluorescence X-rays using a quantitative mechanism employing a calibration curve method for absorption excitation correction and overlap correction. The quantitative mechanism calculates the detection limit of the calibration curve using formula (1) or (2) and displays it on a display.

[0014] [Mathematical Expression 1]

[0015]

[0016]

[0017] [Mathematical Expression 2]

[0018]

[0019]

[0020] In the above,

[0021] W i Analyze the content of component i

[0022] A, B, C: Calibration curve constants

[0023] I i :i component analysis line measurement intensity

[0024] α j Overlap correction coefficient for overlapping line j

[0025] I jovlp Intensity of overlapping line j

[0026] M ij : The absorption and excitation correction coefficient of component j to component i

[0027] C j : content of component j or intensity of the analytical line of component j

[0028] O ij : Overlap correction coefficient of component j to component i

[0029] I BG Background intensity

[0030] σI BG Theoretical standard deviation of background intensity

[0031] t meas : Measurement time.

[0032] According to the fluorescence X-ray analysis apparatus of the present invention, the detection limit is calculated based on a calibration curve formula that includes an absorption excitation correction term and an overlap correction term. Therefore, the effects of absorption excitation correction and overlap correction can be incorporated to appropriately calculate the detection limit.

[0033] In the fluorescence X-ray analysis apparatus of the present invention, regarding the correction components used for calculating the detection limit, the quantitative mechanism can calculate the content of each correction component or the detection limit when the measurement intensity is changed to a specified value and display it on the display. In this case, for example, the detection limit of each standard sample, the detection limit of the representative composition, etc., can be known.

[0034] In the fluorescence X-ray analysis apparatus of the present invention, regarding the correction components used for calculating the detection limit, the quantitative mechanism can calculate the percentage change in the detection limit when the content of each correction component or the measurement intensity changes by a predetermined ratio, and display this calculation on the display. In this case, for example, it can be determined which correction components result in the worst detection limit and which result in the best detection limit.

[0035] This invention also includes any combination of at least two configurations disclosed in the claims and / or description and / or drawings. In particular, this invention includes any combination of more than two technical solutions in the claims. Attached Figure Description

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

[0037] Figure 1 This is a schematic diagram illustrating a fluorescence X-ray analysis apparatus according to one embodiment of the present invention. Detailed Implementation

[0038] The following will describe one embodiment of the fluorescence X-ray analysis apparatus of the present invention. Figure 1 As shown, the fluorescence X-ray analysis apparatus of this embodiment is a scanning type fluorescence X-ray analysis apparatus that measures the intensity of secondary X-rays 5 generated by irradiating sample 1 (including an unknown sample) and sample 14 (including a standard sample) with primary X-rays 3. The apparatus includes: a sample stage 2 for placing samples 1 and 14; an X-ray source 4 such as an X-ray tube for irradiating samples 1 and 14 with primary X-rays 3; a spectrometer 6 for dispersing the secondary X-rays 5, such as fluorescence X-rays, emitted from samples 1 and 14; and a detector 8 for receiving the secondary X-rays 7 dispersed by the spectrometer 6 and detecting their intensity. The output of detector 8 is input to a control mechanism 11, such as a computer, which controls the entire apparatus, via an amplifier, a wave height analyzer, a counting mechanism, etc. (not shown in the figure).

[0039] This embodiment of the fluorescence X-ray analysis apparatus is a wavelength dispersive and scanning fluorescence X-ray analysis apparatus. To change the wavelength of the secondary X-ray 7 incident on the detector 8, it includes a linkage mechanism 10, also known as a goniometer, that links the beam splitter 6 and the detector 8. When the secondary X-ray 5 is incident on the beam splitter 6 at a certain incident angle θ, the extension line 9 of the secondary X-ray 5 and the secondary X-ray 7 diffracted by the beam splitter 6 form a splitting angle 2θ, twice the incident angle θ. To change the wavelength of the split secondary X-ray 7 by altering the splitting angle 2θ, and simultaneously ensure that the split secondary X-ray 7 is incident on the detector 8, the linkage mechanism 10 rotates the beam splitter 6 about an axis O perpendicular to the plane of the paper and passing through its surface center, and rotates the detector 8 about twice the rotation angle along a circle 12 about the axis O. The value of the splitting angle 2θ (2θ angle) is input from the linkage mechanism 10 to the control mechanism 11.

[0040] In this embodiment of the fluorescence X-ray analysis apparatus, the program mounted on the control mechanism 11 includes a quantitative mechanism 13. Based on the measured intensity of the fluorescence X-ray 5, the quantitative mechanism 13, which employs a calibration curve method using absorption excitation correction and overlap correction, determines the content of each component in samples 1 and 14. The selection of standard samples and correction components for generating the calibration curve is performed by the operator, as has always been the case. Furthermore, the quantitative mechanism 13 calculates the detection limit LLD (denoted as LLD) of the calibration curve using formula (1) or (2) and displays it on a display 15 such as a liquid crystal display. The operator selects and specifies which formula (1) or (2) is used. In addition, in this invention, the fluorescence X-ray analysis apparatus can be a wavelength dispersive type and a multi-element simultaneous analysis type fluorescence X-ray analysis apparatus, or an energy dispersive type fluorescence X-ray analysis apparatus.

[0041] [Mathematical Expression 3]

[0042]

[0043]

[0044] [Mathematical Expression 4]

[0045]

[0046]

[0047] In the above,

[0048] W i Analyze the content of component i

[0049] A, B, C: Calibration curve constants

[0050] I i :i component analysis line measurement intensity

[0051] α j Overlap correction coefficient for overlapping line j

[0052] I j ovlp Intensity of overlapping line j

[0053] M ij : The absorption and excitation correction coefficient of component j to component i

[0054] C j : content of component j or intensity of the analytical line of component j

[0055] O ij : Overlap correction coefficient of component j to component i

[0056] IBG Background intensity

[0057] σI BG Theoretical standard deviation of background intensity

[0058] t meas : Measurement time.

[0059] Formulas (1) and (2) are derived from the calibration curve formulas of formulas (3) and (4), respectively.

[0060] [Mathematical Expression 5]

[0061]

[0062] In the above,

[0063] W i Analyze the content of component i

[0064] A, B, C: Calibration curve constants

[0065] I i :i component analysis line measurement intensity

[0066] α j Overlap correction coefficient for overlapping line j

[0067] I j ovlp Intensity of overlapping line j

[0068] M ij : The absorption and excitation correction coefficient of component j to component i

[0069] C j : content of component j or intensity of the analytical line of component j

[0070] O ij : The overlap correction coefficient of component j to component i.

[0071] Here, formula (3) is a calibration curve formula using the JIS method for absorption excitation correction and overlapping correction of content W and measured intensity I, and formula (4) is a calibration curve formula using the ISO method for absorption excitation correction and overlapping correction of content W and measured intensity I. Furthermore, in these calibration curve formulas, measured intensity I is the total intensity.

[0072] For example, the calculation formula (1) for the detection limit can be derived from the calibration curve formula (3) as follows. First, in formula (3), let W=0, and solve for I. Thus, the background intensity I BG It can be calculated as noted in the notes to Formula (1). Furthermore, the theoretical standard deviation σI of the background intensity... BG Through σIBG =(I BG / 1000t meas ) 1 / 2 Calculate it. Furthermore, the detection lower limit LLD can be determined by adjusting σI. BG Multiply three times the slope of the calibration curve and calculate as in formula (1). The calculation formula (2) for the lower detection limit, derived from the calibration curve formula (4), is also the same.

[0073] According to the fluorescence X-ray analysis apparatus of the present invention, the detection limit is calculated based on the calibration curve formula (1) or (2) which includes the absorption excitation correction term and the overlap correction term, thereby enabling the absorption excitation correction and overlap correction to be included in order to appropriately calculate the detection limit.

[0074] Therefore, when making calibration curve formulas (3) and (4), the known content W and measurement intensity I of the calibration component j that the operator has set are used in the multiple standard samples selected by the operator. The detection limit calculation formulas (1) and (2) obtained based on the calibration curve formulas (3) and (4) can not only calculate the detection limit LLD of the calibration curve formulas (3) and (4), but also arbitrarily specify the content of each calibration component j or the measurement intensity Cj to calculate the detection limit LLD.

[0075] Therefore, in the fluorescence X-ray analysis apparatus of this embodiment, regarding the correction component j used for calculating the detection limit, the quantitative mechanism 13 calculates the detection limit LLD of each correction component or the case where the intensity Cj is changed to a specified value and displays it on the display 15.

[0076] The operator can, for example, specify the content of correction component j or the measurement intensity C in each standard sample. j The content or determination intensity C of the correction component j in the representative composition, which is the average value of all standard samples. j The content or intensity of all correction components j without absorption excitation correction and overlap correction; the content (quantitative value) or intensity C of correction component j in unknown samples after quantitative analysis. j In such cases, for example, we can learn the detection limits of each standard sample, the detection limits of representative components, the detection limits without absorption-excitation correction and overlap correction, and the detection limits of each unknown sample. This information can be used as a criterion for judging whether the selection of standard samples and correction components is appropriate.

[0077] Furthermore, in the fluorescence X-ray analysis apparatus of this embodiment, regarding the correction component j used for calculating the detection limit, the quantitative mechanism 13 calculates the content or measurement intensity C of each correction component. jThe percentage change (%) of the lower limit of detection when it changes by a specified proportion, such as 10%, is displayed on the display 15. In this case, by focusing on the absolute value of the percentage change, it can be determined, for example, which correction components j result in the worst lower limit of detection, and which correction components j result in the best lower limit of detection, etc.

[0078] Furthermore, the formula for calculating the lower detection limit in the above explanation is derived from the formula for the total strength calibration curve. If the net strength calibration curve and correction coefficients are obtained through regression calculations, the total strength calibration curve needs to be calculated based on the obtained correction coefficients, and then the formula for calculating the lower detection limit needs to be derived from the total strength calibration curve.

[0079] As described above, preferred embodiments have been illustrated with reference to the accompanying drawings. However, those skilled in the art will readily conceive of various modifications and alterations upon reading this specification. Therefore, such modifications and alterations should be interpreted as still falling within the scope of the invention as defined in the claims.

[0080] [Symbol Explanation]

[0081] 1: Unknown sample

[0082] 3: A single X-ray

[0083] 5: Fluorescent X-rays

[0084] 13: Quantitative Mechanism

[0085] 14: Standard Sample

[0086] 15: Monitor.

Claims

1. A fluorescence X-ray analysis apparatus, 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 fluorescence X-rays using a quantitative mechanism employing a calibration curve method for absorption excitation correction and overlap correction, wherein... The quantitative mechanism calculates the detection limit of the calibration curve using the following formula (1) or (2) and displays it on the display. [Mathematical Expression 1] When A = 0, When A≠0, Theoretical standard deviation of BG strength [Mathematical Expression 2] in, (LLD cannot be calculated when B=0) Theoretical standard deviation of BG strength In the above, W i Analyze the content of component i A, B, C: Calibration curve constants I i :i component analysis line measurement intensity α j Overlap correction coefficient for overlapping line j I j ovlp Intensity of overlapping line j M ij : The absorption and excitation correction coefficient of component j to component i C j : content of component j or intensity of the analytical line of component j O ij : Overlap correction coefficient of component j to component i I BG Background intensity σI BG Theoretical standard deviation of background intensity t meas : Measurement time.

2. The fluorescence X-ray analysis apparatus according to claim 1, wherein, Regarding the correction components used in calculating the lower limit of detection, the quantification mechanism calculates the lower limit of detection for the content of each correction component or when the assay intensity is changed to a specified value and displays it on the display.

3. The fluorescence X-ray analysis apparatus according to claim 1, wherein, Regarding the correction components used in calculating the lower limit of detection, the quantification mechanism calculates the percentage change in the lower limit of detection when the content of each correction component or the measurement intensity changes by a specified ratio and displays it on the display.

Images