Fluorescence x-ray analysis device

Abstract

To provide a fluorescence X-ray analysis device that can highly accurately analyze a sample by a simple configuration.SOLUTION: A fluorescence X-ray analysis device comprises: a sample holding part 1 that holds samples S; an X-ray irradiation unit 2 that is arranged on a front side of the sample S to irradiate the sample with a primary X-ray from the front side; a detection unit 4 that detects fluorescence X-rays K1 and K2 generating from the sample S; and an analysis unit 5 that analyzes the sample on the basis of the detected fluorescence X-rays K1 and K2 by the detection unit 4. A secondary target 3 is arranged on a rear side of the sample S. When a primary X-ray X1 transmitting the sample S by the X-ray irradiation unit 2, and further transmitting in between samples S is irradiated, the secondary target 3 is configured to irradiate the sample S with a secondary X-ray X2 from the rear side.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an X-ray fluorescence analyzer that analyzes a sample by detecting fluorescent X-rays generated from the sample when irradiated with X-rays. [Background technology]

[0002] In recent years, a wide variety of minerals present in the body play an important role in the expression and regulation of various biological functions, and daily intake of a wide variety of minerals is essential to maintain health. Excess or deficiency of essential mineral elements in the body due to over- or under-intake, or abnormal absorption, metabolism, or excretion, can cause various health disorders. For example, calcium is the most abundant mineral in the body, accounting for 1-2% of body weight (about 1 kg for an adult weighing 50 kg), 99% of which is present in hard tissues such as bones and teeth as calcium phosphate (hydroxyapatite) combined with phosphoric acid, and the remaining 1% is present in soft tissues such as blood, muscles, and nerves as ions and various salts, and the Ca concentration in hair is approximately 800 μg / g. Approximately 2,000 mg of zinc is present in the body, with 60% distributed in muscles, 20-30% in bones, 8% in skin and hair, 4-6% in the liver, 2.8% in the digestive tract and pancreas, and 1.6% in the spleen. The average zinc concentration in hair is about 170μg / g. Symptoms of zinc deficiency include dermatitis, taste disorders, chronic diarrhea, immune dysfunction, growth retardation, and gonadal development disorders.

[0003] Traditionally, blood and urine have been used as methods for evaluating the amount of minerals in the body. However, these samples are easily affected by daily fluctuations, and reflect the amount of minerals from the time of collection until several days before, so they are not effective for easily grasping the daily intake. On the other hand, hair is excreted into the hair according to the blood concentration of minerals, and once excreted into the hair, the minerals are fixed and are not excreted into the blood or air. In addition, hair contains about 10 to 50 times more minerals than blood and urine, making it convenient for estimating the amount of minerals accumulated in the body, and it has been reported that hair mineral concentration records the time-dependent fluctuation of the amount of minerals in the blood because hair grows about 1 cm per month. Moreover, hair can be easily collected without invasiveness to the subject, and does not deteriorate even when stored for a long period of time.

[0004] Until now, ICP-AES / MS has been used to analyze hair minerals. However, these analytical methods require more than 100 hairs, and because the hair is dissolved in acid, sample pretreatment is also required, which places an environmental burden on the environment through waste liquid treatment.

[0005] Under such circumstances, the inventors have performed elemental analysis in hair using an X-ray fluorescence analyzer. Specifically, this X-ray fluorescence analyzer includes a sample holder that holds a sample, an X-ray irradiation unit that irradiates the sample with primary X-rays, a detection unit that detects fluorescent X-rays generated from the sample, and an analysis unit that analyzes the sample based on the fluorescent X-rays detected by the detection unit. When the sample is irradiated with primary X-rays from the X-ray irradiation unit, the fluorescent X-rays generated from the sample are detected by the detection unit, and the sample is analyzed by the analysis unit based on the fluorescent X-rays (see, for example, Patent Document 1).

[0006] Meanwhile, fluorescent X-ray analyzers using a secondary target method are also known, which aim to increase the intensity of fluorescent X-rays of trace elements and to increase sensitivity. This secondary target method is a technique in which primary X-rays generated from an X-ray irradiation unit are directly irradiated onto a sample, and fluorescent X-rays generated from the sample are detected by a detection unit, whereas a direct irradiation method irradiates a secondary target with primary X-rays and irradiates the sample with secondary X-rays generated from the secondary target (see, for example, Patent Document 2). According to this method, the sample is irradiated with monochromatic secondary X-rays specific to the secondary target, so that the influence of continuous X-rays contained in the primary X-rays can be reduced and the detection limit of trace elements can be improved. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent Publication No. 2022-133676 [Patent Document 2] Japanese Patent Application Publication No. 7-229861 Summary of the Invention [Problem to be solved by the invention]

[0008] However, conventional X-ray fluorescence analyzers using the secondary target method only irradiate the sample with secondary X-rays generated from the secondary target, and because of the large loss in distance between the sample and the secondary target, the secondary X-rays generated from the secondary target are attenuated before reaching the sample, making it difficult to detect specific elements contained in the sample and sometimes preventing accurate analysis of the sample.

[0009] The present invention has been made in view of the above-mentioned problems, and has an object to provide an X-ray fluorescence analyzer that has a simple configuration and is capable of analyzing a sample with high accuracy. [Means for solving the problem]

[0010] In order to achieve the above-mentioned object, the present invention provides a fluorescent X-ray analysis device comprising a sample holding section for holding a sample, an X-ray irradiation section arranged on the front side of the sample and irradiating the sample with primary X-rays from the front side, a detection section for detecting fluorescent X-rays generated from the sample, and an analysis section for analyzing the sample based on the fluorescent X-rays detected by the detection section, wherein a secondary target is arranged on the back side and / or side side of the sample, and when the secondary target is irradiated with primary X-rays that have passed through the sample from the X-ray irradiation section, it irradiates secondary X-rays from the back side and / or side side of the sample.

[0011] With this, in addition to the primary X-rays irradiated from the front side of the sample by the X-ray irradiation unit, the secondary X-rays irradiated from the back side and / or side of the sample by the secondary target can improve the sensitivity of the fluorescent X-rays generated from the sample, making it possible to analyze the sample with high accuracy.

[0012] Furthermore, when the secondary target is irradiated with primary X-rays that have passed around the sample by the X-ray irradiation unit, secondary X-rays may be irradiated from the back side and / or side of the sample. In this way, in addition to the primary X-rays that have passed through the sample, the secondary target is irradiated with primary X-rays that have passed around the sample, so that the intensity of the secondary X-rays irradiated from the secondary target to the sample is increased, and accordingly the sensitivity of the fluorescent X-rays generated from the sample can be further improved.

[0013] The secondary target may be made of a material that generates secondary fluorescent rays having an excitation energy higher than the absorption edge energy of the element contained in the sample to be analyzed, thereby enhancing the fluorescence excitation effect in which the secondary target serves as an excitation source, thereby further improving the sensitivity of the fluorescent X-rays generated from the sample.

[0014] The secondary target may be formed in a powder or granular form and stored in a rigid and / or flexible storage container. In this way, even if the secondary target is an expensive substance, the cost of the entire apparatus can be reduced by storing the powder or granular secondary target, which is less expensive than a lump, in a rigid and / or flexible storage container. In particular, when the secondary target is stored in a flexible storage container, the shape of the secondary target can be easily deformed in whole or in part, so that the secondary target can be placed at any position on the back or side of the sample, and secondary X-rays generated from the secondary target can be irradiated to the sample from various angles on the back and / or side.

[0015] The sample holder may hold the sample at a position 5 mm or less from the secondary target, whereby secondary X-rays generated from the secondary target can be irradiated onto the sample from the back side and / or the side with almost no attenuation.

[0016] The sample holder may hold a plurality of samples arranged at intervals in a planar direction, and when the secondary target is irradiated with primary X-rays that have passed between the samples, secondary X-rays may be irradiated from the rear side and / or side of each sample. This makes it easier for the primary X-rays from the X-ray irradiator to pass between the samples and reach the secondary target, thereby increasing the intensity of the secondary X-rays irradiated from the secondary target to the sample and improving the sensitivity of the fluorescent X-rays generated from the sample.

[0017] The sample holder may hold each sample such that the ratio of the area through which the primary X-rays from the X-ray irradiator pass to the area of ​​the analysis region in which each sample is placed is 30% to 80%. This ensures that the primary X-rays from the X-ray irradiator pass between the samples and reach the secondary target, so that the secondary X-rays from the secondary target can be reliably irradiated to the sample from the back side and / or side. Effect of the Invention

[0018] According to the present invention, in addition to the primary X-rays irradiated from the front side of the sample by the X-ray irradiation unit, the secondary X-rays irradiated from the back side and / or side of the sample by the secondary target can improve the sensitivity of the fluorescent X-rays generated from the sample, making it possible to analyze the sample with high accuracy. Therefore, even a small amount of sample such as hair can be analyzed with high accuracy, and it is expected to be applied to the beauty and health fields as a specimen for evaluating daily nutritional intake. [Brief description of the drawings]

[0019] [Figure 1] 1 is a schematic diagram showing a configuration of an X-ray fluorescence analysis apparatus according to an embodiment of the present invention. [Diagram 2] 2 is a plan view showing a secondary target, a sample holder, and a sample of the X-ray fluorescence analyzer of FIG. 1. [Diagram 3] 2 is a schematic diagram showing how primary X-rays, secondary X-rays, and fluorescent X-rays are generated by the X-ray fluorescence analyzer of FIG. 1. [Figure 4] 2 is a block diagram showing the electrical configuration of an analysis section of the fluorescent X-ray analyzer of FIG. 1. FIG. [Diagram 5] 2 is a flowchart showing the operation of the X-ray fluorescence analyzer of FIG. 1. [Figure 6] FIG. 13 is a diagram showing a secondary target of an X-ray fluorescence analyzer according to another embodiment. [Figure 7] FIG. 2 is a diagram showing an arrangement of a secondary target and a sample according to an embodiment of the present invention. [Figure 8] FIG. 1 is a graph showing the spectrum of the analysis results of an example of the present invention. [Figure 9] FIG. 13 is a table showing the analysis results of an example of the present invention. [Figure 10] FIG. 9 is a graph showing an overlay of spectra in the energy range of fluorescent X-rays of the element (zinc) being analyzed in the analysis results of FIG. 8. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Next, an embodiment of an X-ray fluorescence analyzer according to the present invention (hereinafter, referred to as the present apparatus) will be described with reference to Figures 1 to 6. In this embodiment, a linear object such as a hair is used as the sample S, and a predetermined element (zinc, calcium, etc.) contained in the sample S is analyzed.

[0021] As shown in Figures 1 and 2, this apparatus comprises a sample holding unit 1 that holds a sample S, an X-ray irradiation unit 2 arranged on the front side of the sample S, a secondary target 3 arranged on the back side of the sample S, a detection unit 4 that detects fluorescent X-rays generated from the sample S, and an analysis unit 5 that analyzes the sample S.

[0022] 2, the sample holder 1 is a pair of tapes that holds the sample S while fixing it to the lower surface of the secondary target 3. The sample holder 1 holds a plurality of samples S in contact with the lower surface of the secondary target 3, arranged at intervals in the planar direction, and both ends of each sample S are adhered and fixed to the lower surface of the secondary target 3. The circular dotted line portion in FIG. 2 indicates the analysis target region R of the sample S.

[0023] The X-ray irradiation unit 2 includes an X-ray tube (not shown) that emits primary X-rays (X1) and a collimator (not shown) that approximately collimates the primary X-rays (X1) emitted from the X-ray tube. The X-ray irradiation unit 2 irradiates the sample S held on the lower surface of the secondary target 3 by the sample holder 1 with the primary X-rays (X1) from the front side of the sample S at a predetermined inclination angle. At this time, when the sample S is irradiated with the primary X-rays (X1) from the front side by the X-ray irradiation unit 2 as shown in FIG. 3, the sample S generates first fluorescent X-rays (K1) corresponding to the primary X-rays (X1) toward the front side of the sample S.

[0024] The secondary target 3 is formed in a lump-like flat plate shape, and when the X-ray irradiation unit 2 irradiates the lower surface with primary X-rays (X1), the secondary target 3 irradiates the sample S from the rear side with secondary X-rays (X2) generated by the fluorescence excitation effect. Specifically, as shown in FIG. 3, when the X-ray irradiation unit 2 irradiates the lower surface with primary X-rays (X1) that pass through the sample S, the secondary target 3 irradiates the sample S from the rear side with secondary X-rays (X2) generated by the fluorescence excitation effect. Furthermore, when the X-ray irradiation unit 2 irradiates the lower surface with primary X-rays (X1) that pass around the sample S (particularly between the samples S), the secondary target 3 irradiates the sample S from the rear side with secondary X-rays (X2) generated by the fluorescence excitation effect. At this time, when the secondary target 3 irradiates the sample S from the rear side with secondary X-rays (X2), the secondary target 3 generates second fluorescent X-rays (K2) corresponding to the secondary X-rays (X2) toward the front side, as shown in FIG. 3.

[0025] Moreover, the secondary target 3 is preferably made of a material corresponding to the element to be analyzed contained in the sample S, and is particularly preferably made of a material that generates secondary fluorescent rays having an excitation energy higher than the absorption edge energy of the element to be analyzed contained in the sample S. For example, when the element to be analyzed contained in the sample S is zinc, the secondary target 3 is preferably made of selenium oxide that generates secondary fluorescent X-rays having an excitation energy higher than the absorption edge energy of zinc. This enhances the fluorescence excitation effect in which the secondary target 3 serves as an excitation source, thereby improving the sensitivity of the fluorescent X-rays generated from the sample S.

[0026] In FIG. 3, for the sake of convenience, the primary X-rays (X1), secondary X-rays (X2), first fluorescent X-rays (K1), and second fluorescent X-rays (K2) are shown separately, but in reality, they are mixed on the front and back sides of the sample S.

[0027] The detection unit 4 is disposed on the front side of the sample S, at a symmetrical position on the opposite side in the horizontal direction to the X-ray irradiation unit 2 with respect to the sample S. This detection unit 4 detects a first fluorescent X-ray (K1) generated from the sample S by the primary X-ray (X1) from the X-ray irradiation unit 2, as well as a second fluorescent X-ray (K2) generated from the sample S by the secondary X-ray (X2) from the secondary target 3.

[0028] As shown in FIG. 4, the analysis unit 5 includes a measurement unit 51 that measures the elements contained in the sample S based on the first fluorescent X-ray (K1) and the second fluorescent X-ray (K2) detected by the detection unit 4, an output unit 52 that outputs the measurement results of the elements contained in the sample S by the measurement unit 51, and a control unit 53 that controls each part of the apparatus.

[0029] Furthermore, the analysis unit 5 is generally executed by a personal computer (PC) connected to the detection unit 4, but may be executed by a cloud server computer connected to the detection unit 4 via a network. In particular, when it is executed by a cloud server computer, the entire device can be made smaller, lighter, and more compact.

[0030] Next, the fluorescent X-ray analysis method using this device will be described with reference to FIG.

[0031] First, a plurality of samples S are held by the sample holder 1 on the lower surface of the secondary target 3 (S1). At this time, the samples S are arranged in a plane direction with a gap therebetween while being in contact with the lower surface of the secondary target 3, with both ends of the samples adhered and fixed, as shown in FIG.

[0032] Next, the X-ray irradiation unit 2 irradiates the sample S held by the sample holder 1 on the underside of the secondary target 3 with primary X-rays (X1) from the front side at a predetermined angle (S2). At this time, the sample S generates first fluorescent X-rays (K1) corresponding to the primary X-rays (X1) from the X-ray irradiation unit 2 toward the front side, as shown in FIG.

[0033] Next, when the primary X-rays (X1) from the X-ray irradiation unit 2 pass through the sample S and are irradiated onto the lower surface of the secondary target 3, the secondary target 3 irradiates the sample S from the back side with secondary X-rays (X2) generated by the fluorescence excitation effect. Furthermore, when the primary X-rays (X1) from the X-ray irradiation unit 2 pass around the sample S (particularly between the samples S) and are irradiated onto the lower surface of the secondary target 3, the secondary target 3 irradiates the sample S from the back side with secondary X-rays (X2) generated by the fluorescence excitation effect (S3). At this time, the sample S generates second fluorescent X-rays (K2) corresponding to the secondary X-rays (X2) from the secondary target 3 toward the front side, as shown in FIG. 3.

[0034] Next, the detection unit 4 detects (S4) a first fluorescent X-ray (K1) generated from the sample S by the primary X-ray (X1) from the X-ray irradiation unit 2, as well as a second fluorescent X-ray (K2) generated from the sample S by the secondary X-ray (X2) from the secondary target 3.

[0035] Next, the analysis unit 5 measures the elements contained in the sample S using the measurement unit 51 based on the first fluorescent X-ray (K1) and the second fluorescent X-ray (K2) detected by the detection unit 4, and outputs the measurement results of the elements contained in the sample S using the output unit 52 (S5).

[0036] Thus, in addition to the primary X-rays (X1) irradiated to the sample S from the front side by the X-ray irradiation unit 2, the secondary X-rays (X2) irradiated to the sample S from the back side by the secondary target improve the sensitivity of the fluorescent X-rays generated from the sample S, making it possible to analyze the sample S with high accuracy. Particularly in this embodiment, in addition to the primary X-rays (X1) that have passed through the sample S, the primary X-rays (X1) that have passed around the sample S (particularly between the samples S) are irradiated to the secondary target 3, so that the intensity of the secondary X-rays (X2) irradiated to the sample S from the secondary target 3 is increased, and accordingly the sensitivity of the fluorescent X-rays generated from the sample S can be further improved.

[0037] In this embodiment, the sample holder 1 holds a plurality of samples S arranged at intervals in the planar direction, but the plurality of samples S may be held arranged without any intervals in the planar direction. However, when a plurality of samples S are held arranged at intervals in the planar direction, in addition to the primary X-rays (X1) that have passed through the samples S, the secondary target 3 is irradiated with the primary X-rays (X1) that have passed between the samples S, and this is preferable because the intensity of the secondary X-rays (X2) generated from the secondary target 3 is enhanced.

[0038] Furthermore, the sample holder 1 is configured to hold a plurality of samples S, but may hold a single sample S.

[0039] Furthermore, the sample holder 1 holds the sample S in contact with the lower surface of the secondary target 3, but it may hold the sample S at a distance from the secondary target 3. However, in order to irradiate the secondary X-rays (X2) from the secondary target 3 from the rear side of the sample S with almost no attenuation, it is preferable to hold the sample S at a position 5 mm or less from the lower surface of the secondary target 3.

[0040] Moreover, the sample holder 1 preferably holds each sample S such that the ratio of the area through which the primary X-rays (X1) from the X-ray irradiator 2 pass to the area of ​​the analysis target region R in which each sample S is arranged is 30% to 80%. This ensures that the primary X-rays (X1) from the X-ray irradiator 2 pass around and between the samples S and reach the secondary target 3, so that the secondary X-rays (X2) from the secondary target 3 can be reliably irradiated from the back side of the sample S. It is preferable that the sample holder 1 holds the sample S in a dispersed (e.g., dispersed in a granular form) manner in the analysis target region R. This ensures that the samples S are dispersed in the secondary target 3, so that excitation from the side of each sample S can be effectively obtained in addition to excitation from the back of each dispersed sample S.

[0041] Further, the sample holder 1 is a pair of tapes that adhere and fix both ends of the sample S, but may be other members, and may be configured separately from or integral with the secondary target 3.

[0042] In addition, the secondary target 3 is configured to irradiate the sample S with secondary X-rays (X2) from the back side, but by arranging the secondary target 3 on the side side of the sample S, the secondary X-rays (X2) from the secondary target 3 may be irradiated onto the sample S from the side side.

[0043] In addition, the secondary target 3 used is formed in a lump state, but it may be in a powder or granular state. In this case, as shown in FIG. 6(a), when the powder or granular secondary target 3 is accommodated in the accommodation container 30, even if the secondary target 3 is an expensive material, the cost of the entire apparatus can be reduced by accommodating the powder or granular secondary target 3, which is less expensive than the lump, in the accommodation container. In particular, as shown in FIG. 6(b), when the secondary target 3 is accommodated in a flexible accommodation container 30' in whole or in part, the shape of the secondary target 3 in whole or in part can be easily deformed, so that the secondary target 3 can be arranged at any position on the back or side of the sample S, and the secondary X-rays (X2) generated from the secondary target 3 can be irradiated to the sample S from various angles on the back and / or side.

[0044] Although the embodiment of the present invention has been described above with reference to the drawings, the present invention is not limited to the illustrated embodiment. Various modifications and variations can be made to the illustrated embodiment within the same scope as the present invention or within an equivalent scope. EXAMPLES

[0045] Next, an embodiment of fluorescent X-ray analysis using this apparatus will be described with reference to FIGS.

[0046] <Analysis equipment configuration> In this example, a tabletop energy dispersive X-ray fluorescence analyzer (EDX-7000, SHIMADS LTD, Japan) was used, which was arranged in the same manner as in Fig. 1. Rh was used as the primary target material (X-ray tube target material) of the X-ray irradiation unit 2, and Se was used as the secondary target 3.

[0047] <Sample S> It is generally known that in hair analysis, external factors such as perms, coloring, and hair cosmetics affect the measurement data. Therefore, sample S was taken from a subject who had not undergone any treatment that would be affected by these factors and who did not use hair cosmetics on a daily basis. First, 30 hairs were taken from the subject's temporal region, washed with acetone (99.5% purity or higher, Hayashi Pure Chemical Industries, Ltd.) and purified water, and then dried at room temperature for about 24 hours. Note that Zn, Se, and other elements do not flow out of the hair when washing with acetone. After these pretreatments, a container was made by attaching a 4 μm thick polypropylene film to a sample cup for fluorescent X-ray analysis as shown in FIG. 7, and 30 hair samples with a hair diameter of about 100 μm, cut to about 30 mm, were attached and fixed to the underside of the film with tape.

[0048] <Analysis Procedure> Measurements were performed using an energy dispersive X-ray fluorescence analyzer with a collimator diameter of 3 mm, tube voltage of 50 kV, vacuum conditions, and without using a filter because the material was unknown. The measurement time was set to 300 seconds because preliminary experiments using this device showed no difference in the measurement results at times longer than 300 seconds. Hair samples S prepared under these conditions were measured five times. After that, the sample cup shown in Figure 7 was filled with secondary target SeO2 powder (purity 99.5%, Nilaco Corporation) to a depth of approximately 5 mm. This places the secondary target of SeO2 powder on the back of the hair sample S, similar to the device shown in Figure 1.

[0049] The reason for selecting Se as the secondary target is that, compared to the analysis target elements Ca and Zn, which have the higher energy ZnKα K-absorption edge energy of 9.66 keV, the Kα of Se generated by the primary X-rays from Rh has a higher excitation energy of 11.22 keV, and it was thought that Se would act as an excitation source, enhancing the characteristic X-rays of Zn due to the fluorescence excitation effect.

[0050] In addition, Se is preferably in the form of a uniform, high-purity, foil-like lump, but since it is difficult to obtain, powdered Se was used. The particle size of the SeO2 powder used in this example is not uniform, and when filling the sample cup, if cavities are formed due to differences in particle size, it will affect the penetration depth of the X-rays. Therefore, the density was increased by vibrating the powder with a hand to prevent cavities from forming in the lower layer. Five measurements were taken in this state.

[0051] In addition, the hair attached to the sample S was removed with precision tweezers, and measurements were performed five times in the same manner with only the SeO2 powder without the hair. The operation of removing the hair after attaching it to the hair and measuring it was performed in order to prevent the density of the SeO2 powder from changing due to vibrations, etc. during the process of attaching the hair.

[0052] In addition, because the hair is held in place by tape at both ends that are not irradiated with X-rays, the adhesion between the hair and the film in the analysis area is low, and the adhesion of washed hair components can be ignored. This procedure was adopted because there is no adhesive that can cause contamination, and the hair removal process is easy.

[0053] <Analysis results and discussion> Figure 8 shows the spectra of (a) hair only, (b) hair and SeO2 powder, and (c) SeO2 powder only. In the spectrum of hair only, peaks of SKα, CaKα, CuKα, and ZnKα, which are abundant in hair, can be confirmed. Furthermore, in sample S, which was filled with SeO2 powder and had hair attached, the background increased due to the influence of the SeO2 powder, but similar peaks of hair components can be seen. The measurement results of sample S, which was only SeO2 powder, show that the SeO2 powder contains almost no S, Ca, or Zn, but there is a CuKα peak and a faint CuKβ peak was also observed, suggesting that it contains a trace amount of Cu as an impurity.

[0054] The fluorescent X-ray intensity obtained in this example was analyzed using a graph analysis software Origin (Origin Lab Corporation). In this analysis, the background intensity was subtracted from the gross intensity including the background intensity to obtain the net intensity, which is the net intensity. The XRF peak is formed by a component of the net net intensity and a component derived from the background intensity. Here, it was assumed that the profile of the background intensity can be approximated by a linear function, and the XRF peak can be approximated by a Gaussian function, and the XRF peak was separated into a net component and a background component. The fitting function f(E) was calculated using the following formula. JPEG2025017011000002.jpg2299y0 is the intercept, α is the slope, A is the parameter that determines the peak intensity, E c is the position of the peak, and w is the width of the peak, which is twice the standard deviation.

[0055] The data obtained five times from each measurement was processed to obtain the average net strength. The net strength calculated from the measurement results of (a) hair only, (b) hair and SeO2 powder, and (c) SeO2 powder only, as well as the net strength of hair only when SeO2 powder was used, calculated by subtracting (c) from (b), and the ratio of increase or decrease are shown in the table in Figure 9. In this table, RSD (Relative Standard Deviation) is the relative standard deviation, which is the standard deviation divided by the average value.

[0056] Comparing the case of hair only with the case of hair and SeO2 powder, the variation of SKα was less than RSD 1% under both conditions, and the ratio of SKα between hair only and the case of SeO2 powder was also less than 1%. S (sulfur) is the mineral most abundant in hair, and is said to have an average content of 5%. In this example, the same hair was used under all conditions, and there was little error even under different conditions, which supports the fact that the error such as the deviation of the irradiation site during the operation of this example was extremely small and appropriate.

[0057] For CaKα, the RSD was 2.6% under both conditions, and when SeO2 powder was present, the intensity was enhanced by 9.4%. This is thought to be due to the SeO2 powder acting as a secondary target 3 to increase the excitation efficiency, resulting in an enhancement effect due to the excitation of elements lower than Se with an atomic number of 34.

[0058] For ZnKα, when only hair was used, the RSD was low at 0.4%, but when SeO2 powder was used, the RSD decreased to 5.5%. This is thought to be due to the influence of the high background caused by the presence of SeO2 powder.

[0059] On the other hand, the intensity of ZnKα increased by 13.9%. Figure 10 shows an overlay of the ZnKα energy range spectra under each condition. When hair and SeO2 powder are used, the background also increases, but it can be seen that the ZnKα peak also increases significantly. As with CaKα, this is thought to be due to increased excitation efficiency due to the SeO2 powder. Excitation efficiency is most efficient when the energy of the X-rays is slightly greater than the binding energy of the excited electrons, and decreases the further away it is from that energy.

[0060] In the present embodiment, SeKα is 11.22 KeV, while ZnKα is close at 8.64 KeV and CaKα is distant at 3.69 KeV. It is therefore believed that the enhancement of ZnKα is high and that of CaKα, which is distant, is low.

[0061] For CuKα, the RSD was 4.4% for hair only and 13.3% for hair and SeO2 powder, showing relatively large variations. When the net CuKα intensity was calculated from this value, the value was higher and negative for SeO2 powder only, and no results were obtained in which the Cu in the SeO2 powder was added to the Cu in the hair. In addition to the background of the SeO2 powder, the SeO2 powder itself contains a higher concentration of Cu than hair, which is presumably what affected the measurement accuracy.

[0062] Hair itself contains Se at about 2 ppm, but this is below the detection limit of this device, and no peak was observed in the analysis of hair alone. On the other hand, high SeKα was observed in the cases of hair and SeO2 powder and SeO2 powder alone. Comparing the measurement results, the RSD was less than 0.1% under both conditions, and almost no variation was observed. However, the SeKα of hair and SeO2 powder was reduced by about 6% compared to the case of Se22 powder alone. This is due to the presence of hair sample S in front of the SeO2 powder, which caused SeKα to be absorbed by the hair. Furthermore, SeLα was significantly lower than the case of SeO2 powder alone. This also suggests that SeLα, which is easily absorbed, was absorbed by the hair.

[0063] In this example, a material that functions as a secondary target was placed on the back side of the sample to verify the occurrence of the excitation effect by the secondary target 3. As a result, in the hair sample S, it was confirmed that the intensity was increased by 9% to 13% in the order of Zn and Ca, which have atomic numbers close to Se. [Explanation of symbols]

[0064] 1...Sample holder 2...X-ray irradiation section 3. Secondary Target 4. Detection section 5…Analysis Department 51...Measuring part 52...Output section 53...Control unit S: Sample

Claims

1. A sample holder for holding a sample; an X-ray irradiation unit that is disposed in front of the sample and irradiates the sample with primary X-rays from the front side; A detection unit that detects fluorescent X-rays generated from a sample; An X-ray fluorescence spectrometer comprising an analysis unit that analyzes a sample based on the X-ray fluorescence detected by the detection unit, A secondary target is disposed on the backside and / or side of the specimen; The secondary target is characterized in that when the primary X-rays transmitted through the sample by the X-ray irradiation unit are irradiated to the sample, the secondary X-rays are irradiated from the back side and / or the side side of the sample.

2. 2. The X-ray fluorescence apparatus according to claim 1, wherein the secondary target is further configured to irradiate the sample with secondary X-rays from a rear side and / or a side side when the secondary target is irradiated with primary X-rays that have passed around the sample from the X-ray irradiation unit.

3. 3. The X-ray fluorescence analysis apparatus according to claim 1, wherein the secondary target is made of a material that generates secondary fluorescent rays having excitation energy higher than the absorption edge energy of an element contained in a sample that is an object of analysis.

4. 3. The X-ray fluorescence analysis apparatus according to claim 1, wherein the secondary target is formed in a powder or granular form and is accommodated in a rigid and / or flexible container.

5. 3. The X-ray fluorescence analysis apparatus according to claim 1, wherein the sample holder holds the sample at a position 5 mm or less away from the secondary target.

6. The sample holder holds a plurality of samples arranged at intervals in a planar direction, 3. The X-ray fluorescence analysis apparatus according to claim 2, wherein the secondary target irradiates each sample with secondary X-rays from a rear side and / or a side side when the secondary target is irradiated with primary X-rays that have passed between the samples.

7. 7. The X-ray fluorescence analysis apparatus according to claim 6, wherein the sample holding unit holds each sample such that a ratio of an area through which the primary X-rays from the X-ray irradiation unit pass to an area of ​​an analysis target region in which each sample is placed is 30% to 80%.

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