JP6994755B2 - Fluorescent X-ray analyzer and fluorescent X-ray analysis method - Google Patents

Description

The present invention relates to a fluorescent X-ray analyzer and a fluorescent X-ray analysis method capable of detecting metal elements and the like contained in a sample of food, medical products, and the like.

In fluorescent X-ray analysis, a sample is irradiated with X-rays emitted from an X-ray source, and fluorescent X-rays having element-specific energy emitted from the sample are detected by an X-ray detector, and a spectrum is obtained from that energy. Is obtained, and qualitative analysis or quantitative analysis of the sample is performed. This fluorescent X-ray analysis is widely used in processes, quality control, etc. because it can analyze a sample non-destructively and quickly. In recent years, it has been studied to use fluorescent X-ray analysis for detection and quantification of cadmium (Cd) and the like in foods.

For samples containing light elements such as rice grains and rice flour as the main component, ICP (inductively coupled plasma emission spectrometry) or the like has conventionally been performed to detect heavy metals such as cadmium contained in trace amounts, but the sample is liquefied. Pretreatment is required, and it takes time and effort to measure, and there is a problem that the analysis result varies depending on the analyst. However, the fluorescent X-ray analysis has an advantage that the measurement can be performed without pretreatment, and the analysis result has less variation depending on the analyst than the ICP. Even in such fluorescent X-ray analysis, the detection limit of fluorescent X-ray analysis is about 1 mg / kg, while the cadmium content in food is a regulated value (for example, 0.4 mg / kg or less in the case of rice). , Sufficient detection limit has not been obtained.

Therefore, in the conventional measurement of samples containing light elements such as foods as the main component, the detection limit on the order of 0.1 mg / kg, which is the regulation value for elements that generate relatively high-energy fluorescent X-rays such as cadmium, has been set. In order to realize this, a fluorescent X-ray analyzer in which an X-ray source and an X-ray detector are arranged so as to face each other with respect to the sample container has been developed (see Patent Document 1).
This fluorescent X-ray analyzer increases the sensitivity of the X-rays obtained by bringing the X-ray source and the X-ray detector closer to the sample container, and further, the sample itself contains a light element that is difficult to absorb X-rays as a main component. Therefore, by irradiating the area in front of the X-ray detector, which can measure with the highest sensitivity in the sample container, with sufficient excited X-rays and also irradiating the entire sample container, high energy such as cadmium, which has a relatively deep analysis depth. X-ray fluorescence is also detected from the sample at the back of the sample container, and the sensitivity and detection limit are improved. Here, the analysis depth is the depth at which the fluorescent X-ray of the element of interest in the sample is detected, and the fluorescent X-ray energy of the element of interest (the element to be quantified) and the matrix (coexistence) which is the main component in the sample. It is closely related to the element), and in general, the higher the fluorescent X-ray energy of the element of interest and the lower the average atomic number of the matrix in the sample, the deeper the analysis depth. For example, when rice grains or rice flour are the main components, the analysis depth is about several tens of mm for cadmium and about 1 mm for arsenic.

In addition, when measuring elements such as arsenic (As) that generate fluorescent X-rays with relatively lower energy than cadmium, the fluorescent X-rays generated in the sample at the back of the sample container are absorbed in the sample container. In addition to not contributing to the improvement of sensitivity, scattered X-rays with higher energy than the fluorescent X-rays are not absorbed and become noise that enters the X-ray detector and increases the background intensity. By changing this, a fluorescent X-ray analyzer has been developed that measures an element that generates fluorescent X-rays having a relatively lower energy than that of cadmium or the like with high sensitivity (see Patent Document 2).

Japanese Patent No. 4874118 Japanese Patent No. 4854005

The following problems remain in the above-mentioned conventional technology.
That is, in the above-mentioned conventional fluorescent X-ray analyzer, for example, when trying to measure elements having different analysis depths (for example, cadmium and arsenic) with high sensitivity, a sample container for cadmium and a sample for arsenic having different shapes are used. It was necessary to prepare a container separately, fill these different sample containers with samples, and measure them separately. Therefore, there is an inconvenience that the required amount of sample is increased and the preparation time for sample preparation and replacement of the measured sample is also required.

The present invention has been made in view of the above-mentioned problems, and provides a fluorescent X-ray analyzer and a fluorescent X-ray analysis method capable of measuring elements having different analysis depths in the same sample container without changing the arrangement. The purpose.

The present invention has adopted the following configuration in order to solve the above problems. That is, the fluorescent X-ray analyzer according to the first invention includes a sample container that can store a sample, an X-ray source that irradiates the sample with primary X-rays, and the sample that is irradiated with the primary X-rays. The irradiation range changing mechanism comprises a detector for detecting fluorescent X-rays generated from the sample container and an irradiation range changing mechanism capable of changing the range of irradiating the sample with the primary X-rays in the sample container. Partial irradiation of the sample near the wall surface of the sample container facing the detector at least, and irradiation of the sample in the sample container with the primary X-ray in a wider area than the partial irradiation. It is characterized by being able to be changed to a wide range irradiation.

In this fluorescent X-ray analyzer, the irradiation range changing mechanism is a partial irradiation that irradiates a sample near the wall surface of the sample container facing the detector with primary X-rays, and a sample in the sample container in a wider area than the partial irradiation. Since it is possible to change to wide-range irradiation that irradiates primary X-rays, the irradiation area can be adjusted to wide-range irradiation or partial irradiation according to the analysis depth of the element of interest. That is, when measuring an element of interest having a high fluorescent X-ray energy, it is performed by irradiating a wide range according to the analysis depth, and high-energy fluorescent X-rays are also detected from the sample on the back side of the sample container, and the fluorescent X is detected. When measuring an element of interest with low line energy, the analysis depth becomes shallow, so by partially irradiating the sample near the detector in the sample container, low-energy fluorescent X-rays can be obtained closer to the detector. It is possible to detect from the sample, suppress scattered X-rays that are noise components from the sample at the back of the sample container, and efficiently detect the fluorescent X-rays of the element of interest.

The fluorescent X-ray analyzer according to the second invention has a plurality of irradiation range changing mechanisms arranged between the X-ray source and the sample container and capable of transmitting the primary X-rays in the first invention. A collimeter having a transmission window and a collimeter moving mechanism capable of transmitting the primary X-ray to any one of the plurality of transmission windows and moving the collimeter relative to the X-ray source are provided. As the transmission window, the collimator is a transmission window for a portion capable of irradiating a region close to the detector with the primary X-ray during the partial irradiation, and a region wider than the partial irradiation during the wide range irradiation. The sample in the sample container is characterized by having a transmission window for a wide range capable of irradiating the primary X-ray.
That is, in this fluorescent X-ray analyzer, the collimator has a partial transmission window capable of irradiating a region close to the detector with primary X-rays during partial irradiation, and a sample in a region wider than the partial irradiation during wide-range irradiation. Since the sample in the container has a wide-range transmission window that can irradiate the sample with primary X-rays, the collimator is moved by the collimeter moving mechanism, and the wide-range transmission window or partial transmission window is used as a transmission window through which the primary X-rays pass. By selecting, it is possible to easily switch between wide-range irradiation and partial irradiation.

In the fluorescent X-ray analyzer according to the third invention, in the first invention, the irradiation range changing mechanism is arranged between the X-ray source and the sample container, and the transmission window capable of transmitting the primary X-ray. A collimator having a The transmission window can be moved to a position where the primary X-ray can be irradiated to the sample in the sample container in a region wider than the irradiation, and in the sample container close to the detector at the time of partial irradiation. It is characterized in that the transmission window can be moved to a position where the primary X-ray can be irradiated to the sample in a narrower range than the wide range irradiation.
That is, in this fluorescent X-ray analyzer, the collimator moving mechanism can move the transmission window to a position where primary X-rays can be irradiated in a wider area than partial irradiation during wide-range irradiation, and at the time of partial irradiation. Since the transmission window can be moved to a position close to the detector and capable of irradiating primary X-rays in a narrower range than the wide range irradiation, wide range irradiation and partial irradiation can be easily performed simply by adjusting the position of the transmission window. Can be easily done.

In any one of the first to third inventions, the fluorescent X-ray analyzer according to the fourth invention has the wide range according to the analysis depth of the element of interest among the fluorescent X-rays by the irradiation range changing mechanism. It is characterized in that the irradiation region of the primary X-ray between the irradiation and the partial irradiation can be adjusted.
That is, in this fluorescent X-ray analyzer, the irradiation range changing mechanism can adjust the irradiation region of the primary X-ray between wide-range irradiation and partial irradiation according to the analysis depth of the element of interest among the fluorescent X-rays. Depending on the irradiation range suitable for the element of interest, high-precision analysis is possible with wide-range irradiation and partial irradiation.

In any one of the first to fourth inventions, the fluorescent X-ray analyzer according to the fifth invention allows the sample container to transmit the primary wall surface through which the primary X-rays can pass and the fluorescent X-rays. The X-ray source is arranged adjacent to the first wall surface, the detector is arranged adjacent to the second wall surface, and the irradiation range changing mechanism is provided. It is characterized in that the primary X-ray is irradiated to the vicinity of the inner surface of the second wall surface at the time of the partial irradiation.
That is, in this fluorescent X-ray analyzer, the detector is arranged adjacent to the second wall surface, and the irradiation range changing mechanism irradiates the vicinity of the inner surface of the second wall surface with primary X-rays at the time of partial irradiation. The detector can efficiently measure only fluorescent X-rays generated radially from the sample near the inner surface of the second wall surface without generating scattered X-rays from the sample on the back side of the sample container.

In any one of the first to fifth inventions, the fluorescent X-ray analyzer according to the sixth invention has the sample as a main component of a light element, and the irradiation range changing mechanism is among the elements in the sample. Switch to the wide range irradiation when detecting at least one of Cd, Sn, Sb, Ba, and switch to the partial irradiation when detecting at least one of As, Pb, Hg, Br among the elements in the sample. It is characterized by being possible.
That is, in this fluorescent X-ray analyzer, the irradiation range changing mechanism switches to wide-range irradiation when detecting at least one of relatively high-energy Cd, Sn, Sb, and Ba among the elements in the sample, and is in the sample. Since it is possible to switch to partial irradiation when detecting at least one of As, Pb, Hg, Br, which has a lower energy than the above-mentioned Cd, Sn, Sb, Ba among the elements of Cd, Sn, Sb, Ba. At least one of As, Pb, Hg, and Br can be measured with high sensitivity in the same sample container without changing the arrangement.

The fluorescent X-ray analyzer according to the seventh aspect of the invention is characterized in that, in any one of the first to sixth aspects, the sample is rice grain, rice flour, or a fluid solid or liquid.
That is, in this fluorescent X-ray analyzer, when the sample is rice grains, rice flour, or a fluid solid or liquid (for example, porridge), rice grains, rice flour, or heavy metals contained in the fluid solid or liquid. Of these, a plurality of elements having different analysis depths can be measured with high sensitivity without changing the sample container and arrangement.

The fluorescent X-ray analysis method according to the eighth invention is a fluorescent X-ray analysis method in which a sample in a sample container is irradiated with primary X-rays from an X-ray source and fluorescent X-rays generated from the sample are detected by a detector. The partial irradiation step of irradiating the sample near the wall surface of the sample container facing the detector at least with the primary X-ray, and the sample in the sample container in a region wider than the partial irradiation. It is characterized by having a wide range irradiation step of irradiating primary X-rays.
That is, in this fluorescent X-ray analysis method, at least the partial irradiation step of irradiating the sample near the wall surface of the sample container facing the detector with the primary X-ray, and the primary X to the sample in the sample container in a wider area than the partial irradiation. Since it has a wide-range irradiation step of irradiating lines, it is possible to measure elements with a deep analysis depth in the wide-range irradiation step with high sensitivity while keeping the same sample container, and in the partial irradiation step, the analysis depth can be measured. Shallow elements can be measured with high sensitivity.

According to the present invention, the following effects are obtained.
That is, according to the fluorescent X-ray analyzer and the fluorescent X-ray analysis method according to the present invention, at least partial irradiation for irradiating a sample near the wall surface of the sample container facing the detector with primary X-rays is wider than partial irradiation. Since it is possible to change to wide-range irradiation in which the sample in the sample container is irradiated with primary X-rays in the region, high-energy fluorescent X-rays can be sampled by performing wide-range irradiation when measuring elements with a deep analysis depth. It is also detected from the sample on the back side of the container, and when measuring elements with a shallow analysis depth, partial irradiation is performed to detect low-energy fluorescent X-rays from the sample closest to the detector, and the sample container It is possible to efficiently detect low-energy fluorescent X-rays by suppressing noise caused by the generation of high-energy scattered X-rays from the back side.
Therefore, in the fluorescent X-ray analyzer and the fluorescent X-ray analysis method of the present invention, it is possible to measure a plurality of elements having different analysis depths with good sensitivity without changing the sample container and arrangement, and the required sample amount. And the preparation time for measurement can be reduced to about half.

FIG. 3 is a schematic diagram of an X-ray optical system showing a wide range irradiation step (a) and a partial irradiation step (b) in the first embodiment of the fluorescent X-ray analyzer and the fluorescent X-ray analysis method according to the present invention. In the first embodiment, it is a perspective view which shows the collimator. FIG. 3 is a schematic diagram of an X-ray optical system showing a wide range irradiation step (a) and a partial irradiation step (b) in the second embodiment of the fluorescent X-ray analyzer and the fluorescent X-ray analysis method according to the present invention.

Hereinafter, the first embodiment of the fluorescent X-ray analyzer and the fluorescent X-ray analysis method according to the present invention will be described with reference to FIGS. 1 and 2.

As shown in FIG. 1, the fluorescent X-ray analyzer 1 of the present embodiment irradiates the sample container 4 capable of storing the sample S in the form of granules or powder and the primary X-ray X1 with respect to the sample S. The range of irradiating the X-ray source 2, the detector 3 for detecting the fluorescent X-ray X2 generated from the sample S irradiated with the primary X-ray X1, and the sample S in the sample container 4 with the primary X-ray X1. It is equipped with a changeable irradiation range changing mechanism 5.

As shown in FIG. 1B, the irradiation range changing mechanism 5 is a partial irradiation that irradiates the sample S near the second wall surface 4b of the sample container 4 facing the detector 3 with the primary X-ray X1. As shown in FIG. 1A, it is possible to change to wide-range irradiation in which the sample S in the sample container 4 is irradiated with the primary X-ray X1 in a region A1 wider than the partial irradiation.
At the time of the partial irradiation, the primary X-ray X1 is irradiated to the region A2 of the sample S in the sample container 4 near the detector 3.

That is, as shown in FIGS. 1 and 2, the irradiation range changing mechanism 5 has a plurality of transmission windows 6a to 6c arranged between the X-ray source 2 and the sample container 4 and capable of transmitting the primary X-ray X1. A collimator 6 and a collimator moving mechanism 7 that can move the collimator 6 relative to the X-ray source 2 so that the primary X-ray X1 can pass through any one of the plurality of transmission windows 6a to 6c are provided. There is.

The collimator 6 is made of an element or a metal plate having a thickness that does not allow the primary X-ray X1 to pass through, and can irradiate the region A2 close to the detector 3 with the primary X-ray X1 as a transmission window during partial irradiation. It has a partial transmission window 6b and a wide-range transmission window 6a capable of irradiating the sample S in the sample container 4 with the primary X-ray X1 in a region A1 wider than the partial irradiation during wide-range irradiation. In the present embodiment, the region A1 wider than the partial irradiation is set for the entire sample S in the sample container 2.

The wide-range transmission window 6a has an opening diameter set so that the primary X-ray X1 from the X-ray source 2 irradiates the entire sample S in the sample container 4 at a large solid angle. The opening diameter is set smaller than that of the wide-range transmission window 6a so that the sample S in the sample container 4 is partially irradiated with the primary X-ray X1 at a small solid angle.
The central axis of the wide-range transmission window 6a coincides with the axis C of the collimator 6, but the partial transmission window 6b is formed so that the central axis is offset from the axis C. The axis C of the collimator 6 is set to coincide with the optical axis of the primary X-ray X1. Further, the axis C of the collimator 6 is set so that the wide-range transmission window 6a is on the back side in the direction perpendicular to the paper surface of FIG.

Further, in the collimator 6, in addition to the wide-range transmission window 6a and the partial transmission window 6b, a transmission window 6c opened at a position deviated from the axis C is formed.
The transmission windows 6a to 6c are through holes in which the opening shape, opening diameter, and arrangement are set according to the irradiation region and irradiation direction of the primary X-ray X1.
In addition, in these transmission windows 6a to 6c, a primary filter such as Mo or Zr that absorbs primary X-rays in the energy band serving as a background may be installed in order to reduce the background strength.

The collimator 6 is movably installed between the sample container 4 and the X-ray source 2.
The collimator moving mechanism 7 is composed of a motor or the like, and the collimator 6 can be moved in the axis C direction, and the distance between the collimator 6 and the X-ray source 2 can be adjusted. That is, the collimator moving mechanism 7 can move the collimator 6 to arrange any of the transmission windows 6a to 6c facing the X-ray source 2.

The sample container 4 has a first wall surface 4a through which primary X-rays X1 can pass and a second wall surface 4b through which fluorescent X-rays X2 can pass. The first wall surface 4a and the second wall surface 4b form a V-shaped bottom surface of the sample container 4.
The sample container 4 is made of an organic material such as plastic, which is relatively easy to transmit X-rays, or a material such as aluminum, silicon, or magnesium.
The sample container 4 is supported by a sample table (not shown). For example, the sample container 4 is inserted into the installation hole made in the sample table from above, and the upper part of the sample container 4 abuts on the installation hole, so that the first wall surface 4a and the second wall surface 4b are exposed downward. The sample container 4 is installed in this state.

The X-ray source 2 is arranged adjacent to the first wall surface 4a so as to face the first wall surface 4a, and the detector 3 is arranged adjacent to the second wall surface 4b. That is, the X-ray source 2 is arranged close to the outer surface of the first wall surface 4a and the detector 3 is arranged to face each other close to the outer surface of the second wall surface 4b, respectively. It is located below.
Since the detector 3 is arranged adjacent to the second wall surface 4b in this way, the irradiation range changing mechanism 5 irradiates the vicinity of the inner surface of the second wall surface 4b with the primary X-ray X1 at the time of partial irradiation. It is set to do. In particular, since the first wall surface 4a and the second wall surface 4b form a V-shaped bottom surface, the X-ray source 2 and the detector 3 do not interfere with each other, so that they are close to each wall surface of the sample container 4. Can be placed. Further, at the time of partial irradiation, it is easy to partially irradiate the primary X-ray X1 from the side of the first wall surface 4a toward the vicinity of the inner surface of the second wall surface 4b.

In the present embodiment, the sample S is mainly composed of light elements such as C, O, H, and N, and is, for example, rice grains or grains such as rice flour and wheat flour, foods such as beans, medical products, and chemical industrial products. And so on.
The light element is an element through which the primary X-ray X1 is easily transmitted, and the element having a smaller atomic number has a higher transmittance of X-rays, and is an element such as C, O, H, N or Al, Mg, or an organic material. Also includes.

The irradiation range changing mechanism 5 is particularly composed of elements such as Cd, Sn, Sb, and Ba that generate energy per 20 to 30 KeV, which has a relatively high energy of fluorescent X-rays among the elements in the sample S. A trace amount of elements such as As, Pb, Hg, Br that generate energy per 10 KeV, which is lower energy than Cd etc. among the elements in sample S by irradiating a wide range when detecting trace heavy metals. When detecting heavy metals, it is possible to narrow the area closer to the detector 3 and partially irradiate the metal.
These elements of interest to be detected are elements that generate fluorescent X-rays having at least a higher energy than the element containing the main component.

The X-ray source 2 includes an X-ray tube 2a capable of irradiating primary X-ray X1, and thermions generated from the filament (cathode) in the tube 2a are between the filament (cathode) and the target (anode). X-rays that are accelerated by the voltage applied to the target and collide with the target W (tungsten), Mo (molybdenum), Cr (chromium), etc. are used as primary X-rays X1 from an emission window (not shown) such as beryllium foil. It emits.

The detector 3 includes a semiconductor detection element (for example, a Si (silicon) element which is a pin structure diode) (not shown) via an X-ray incident window (not shown), and the fluorescent X-ray X2 is used as a semiconductor detection element. When one X-ray photon is incident, a current pulse corresponding to this one X-ray photon is generated. The instantaneous current value of this current pulse is proportional to the energy of the incident characteristic X-ray. Further, the detector 3 is set to convert a current pulse generated by the semiconductor detection element into a voltage pulse, amplify it, and output it as a signal.
A shield plate 8 is provided between the sample container 4 and the detector 3 so that the primary X-ray X1 from the X-ray source 2 does not directly enter the detector 3.

In addition, the fluorescent X-ray analyzer 1 of the present embodiment further includes an analyzer (not shown) and a control unit (not shown).
The analyzer is a wave height analyzer (multi-channel analyzer) that obtains the wave height of a voltage pulse from the signal and generates an energy spectrum.
The control unit is a computer composed of a CPU or the like, is connected to a display or the like, and has a function of displaying an analysis result on the display.

Next, the fluorescent X-ray analysis method using the fluorescent X-ray analyzer 1 of the present embodiment will be described below.

First, an appropriate amount of a granular or powdery sample S (for example, rice grain or rice flour) is filled in the sample container 4, and the sample container 4 filled with the sample S is set on the sample table.
In the fluorescent X-ray analysis method of the present embodiment, the partial irradiation step of irradiating the region A2 closest to the detector 3 of the sample S in the sample container 4 with the primary X-ray X1 and the sample in the region A1 wider than the partial irradiation. It has a wide-range irradiation step of irradiating the sample S in the container 4 with the primary X-ray X1, and the analysis is performed by switching between the partial irradiation step and the wide-range irradiation step.

When detecting an element having a deep analysis depth, for example, Cd, Sn, Sb, Ba, etc. as an element of interest among the elements in the sample S, it is measured by a wide range irradiation step as shown in FIG. 1 (a). I do.
That is, in the wide-range irradiation step, the wide-range transmission window 6a faces the X-ray source 2 by the irradiation range changing mechanism 5, and the optical axis XC of the primary X-ray X1 emitted through the emission window is the central axis of the wide-range transmission window 6a. The collimator 6 is moved so as to be coaxial with. The central axis of the detector 3 is set so as to intersect the optical axis XC of the primary X-ray X1 at a right angle.

In this state, when the primary X-ray X1 is emitted from the X-ray source 2, the primary X-ray X1 is radiated through the wide-range transmission window 6a over the entire first wall surface 4a with a wide solid angle and inside the sample container 4. The entire sample S of the above is irradiated. In particular, in the sample S containing a light element such as a rice grain as a main component, the primary X-ray X1 is transmitted deep inside and the entire inside of the sample S is excited including the element of interest to generate fluorescent X-ray X2. Therefore, the fluorescent X-ray X2 generated from the entire sample S in the sample container 4 can be incident on the detector 3 adjacent to the second wall surface 4b. At this time, the detector 3 can also detect the high-energy fluorescent X-ray X2 from the sample S located at the back side of the sample container 4.

Next, when detecting an element having a shallow analysis depth, particularly at least one of As, Pb, Hg, and Br as the element of interest among the elements in the sample S, as shown in FIG. 1 (b), Measurement is performed by a partial irradiation process.
That is, in the partial irradiation step, the partial transmission window 6b faces the X-ray source 2 by the irradiation range changing mechanism 5, and the central axis of the partial transmission window 6b is displaced with respect to the optical axis XC of the primary X-ray X1. Move the collimator 6. At this time, the positional relationship between the collimator 6 and the X-ray source 2 is the same as in the wide-range irradiation step, but the irradiation direction of the primary X-ray X1 and the irradiation stereoscopic angle of the sample container 4 are different, and the primary X-ray is emitted. The irradiation direction of X1 is directed to the vicinity of the inner surface of the second wall surface 4b by the partial transmission window 6b, and the irradiation diameter is narrowed compared to the wide range irradiation step.

In this state, when the primary X-ray X1 is emitted from the X-ray source 2 through the emission window, the primary X-ray X1 passes through the partial transmission window 6b and forms a narrow solid angle toward the second wall surface 4b of the first wall surface 4a. It is emitted from the sample container 4 and is irradiated from the second wall surface 4b in the sample container 4 to the sample S in the region A2 according to the analysis depth of the element of interest. Therefore, the fluorescent X-ray X2 generated from the sample S near the inner surface (region A2) of the second wall surface 4b is incident on the detector 3 adjacent to the second wall surface 4b. At this time, the detector 3 can detect the low-energy fluorescent X-ray X2 from the sample S close to the detector 3. Further, since the primary X-ray X1 is not irradiated to the inner side of the sample container 4 away from the second wall surface 4b, fluorescent X-rays are not generated from that region, and high-energy scattered X-rays that become noise are suppressed. can do.

As described above, in the fluorescent X-ray analyzer 1 of the present embodiment, the irradiation range changing mechanism 5 irradiates the sample S near the second wall surface 4b of the sample container 4 facing the detector 3 with the primary X-ray X1. Since it is possible to change between partial irradiation and wide-range irradiation in which the sample S in the sample container 4 is irradiated with the primary X-ray X1 in a region A1 wider than the partial irradiation, the irradiation region is wide-range according to the analysis depth of the element of interest. It can be adjusted to irradiation and partial irradiation.

That is, when measuring an element of interest having a high fluorescent X-ray energy, it is performed by irradiating a wide range according to the analysis depth, and high-energy fluorescent X-rays are also detected from the sample S on the back side of the sample container 4. When measuring an element of interest with low fluorescent X-ray energy, the analysis depth becomes shallow. Therefore, by partially irradiating the sample S near the detector 3 of the sample container 4, low-energy fluorescent X-rays are emitted. It is possible to detect X2 from the sample S near the detector 3, suppress scattered X-rays that are noise components from the sample S at the back of the sample container 4, and efficiently detect the fluorescent X-ray X2 of the element of interest. can.
In this way, by switching the irradiation region according to the analysis depth of the element to be measured and irradiating the beam of the primary X-ray X1, the fluorescent X-ray X2 of the element of interest is efficiently detected by the detector 3. be able to.

In particular, the irradiation range changing mechanism 5 switches to wide-range irradiation when detecting Cd, Sn, Sb, Ba, etc. among the elements in the sample S, and As, Pb, Hg, Br, etc. among the elements in the sample S. Since it is possible to switch to partial irradiation at the time of detection, Cd, Sn, Sb, Ba, etc. and As, Pb, Hg, Br, etc. should be measured with high sensitivity without changing the arrangement in the same sample container 4. Can be done.

In this way, the irradiation range changing mechanism 5 can adjust the irradiation region of the primary X-ray X1 between wide-range irradiation and partial irradiation according to the analysis depth of the element of interest in the fluorescent X-ray X2. A suitable irradiation range enables highly accurate analysis with wide-range irradiation and partial irradiation.
When the sample S is a rice grain, rice flour, or a fluid solid or liquid (for example, porridge), the above-mentioned heavy metals contained in the rice grain, rice flour, or the fluid solid or liquid have different analytical depths. A plurality of elements can be measured with high sensitivity without changing the sample container 4 and the arrangement.

Further, the collimator 6 has a transmission window 6b for a portion capable of irradiating the region A2 closest to the detector 3 with the primary X-ray X1 at the time of partial irradiation, and a sample container 4 in a region wider than the partial irradiation at the time of wide-range irradiation. Since the sample S in the sample S has a wide-range transmission window 6a capable of irradiating the primary X-ray X1, the collimeter 6 is moved by the collimeter moving mechanism 7, and the wide-range transmission window is used as a transmission window through which the primary X-ray X1 passes. By selecting 6a or the partial transmission window 6b, it is possible to easily switch between wide-range irradiation and partial irradiation.

Further, the detector 3 is arranged adjacent to the second wall surface 4b, and the irradiation range changing mechanism 5 irradiates the vicinity of the inner surface of the second wall surface 4b with the primary X-ray X1 at the time of partial irradiation. The detector 3 can efficiently measure the fluorescent X-rays X2 generated radially from the sample S near the inner surface of the wall surface 4b.
As described above, in the fluorescent X-ray analysis method of the present embodiment, the partial irradiation step of irradiating the region A2 closest to the detector 3 in the sample S in the sample container 4 with the primary X-ray X1 and the region wider than the partial irradiation. Since the sample S in the sample container 4 has a wide-range irradiation step of irradiating the primary X-ray X1 and the analysis is performed by switching between the partial irradiation step and the wide-range irradiation step, wide-range irradiation is performed with the same sample container 4 as it is. Elements with a deep analysis depth can be measured with high sensitivity in the process, and elements with a shallow analysis depth can be measured with high sensitivity in the partial irradiation step.

Next, a second embodiment of the fluorescent X-ray analyzer and the fluorescent X-ray analysis method according to the present invention will be described below with reference to FIG. In the following description of the embodiment, the same components described in the above embodiment are designated by the same reference numerals, and the description thereof will be omitted.

The difference between the second embodiment and the first embodiment is that in the first embodiment, a plurality of transmission windows 6a to 6c are switched according to the analysis depth of the element of interest, whereas in the second embodiment. In the fluorescent X-ray analyzer 21, as shown in FIG. 3, the collimator 26 has only one wide-range transmission window 6a as a transmission window, and the collimator moving mechanism 25 changes the position of the wide-range transmission window 6a. The point is that the wide range irradiation and the partial irradiation are changed.

That is, in the second embodiment, the collimator moving mechanism 25 can move the transmission window 6a to a position where the primary X-ray X1 can be irradiated to the sample S in the sample container 4 in a region wider than the partial irradiation during a wide range irradiation. In addition, the transmission window 6a can be moved to a position where the primary X-ray X1 can be irradiated to the sample S in the sample container 4 near the detector 3 in a narrower range than the wide range irradiation at the time of partial irradiation.

When a wide range irradiation is performed with an element having a deep analysis depth as the element of interest, the collimator moving mechanism 25 has the optical axis of the X-ray source 2 as the central axis of the wide range transmission window 6a as shown in FIG. 3A. Move the collimator 26 so that it matches the XC. Further, when partial irradiation is performed with an element having a shallow analysis depth as the element of interest, the collimator moving mechanism 25 has an X-ray source 2 as the central axis of the wide-range transmission window 6a as shown in FIG. 3 (b). The collimator 26 is moved in the Y direction of the arrow in the figure so as to deviate from the optical axis XC. At this time, a part of the primary X-ray X1 is blocked by the wide-range transmission window 6a that is displaced, and the sample S on the back side of the sample container 4 away from the second wall surface 4b is irradiated with the primary X-ray X1. Not done.

At this time, an obstacle plate (not shown) is provided between the X-ray source 2 and the detector 3 so that the primary X-ray X1 from the X-ray source 2 does not directly enter the detector 3 without passing through the sample container 4. May be provided.
Further, in the second embodiment, the collimeter 26 having only one wide-range transmission window 6a is used as the transmission window, but as in the first embodiment, a plurality of collimeters having a plurality of transmission windows are used. The position of the wide-range transmission window 6a may be changed so that not only wide-range irradiation but also partial irradiation can be performed.

As described above, in the fluorescent X-ray analyzer 21 of the second embodiment, the collimator moving mechanism 25 has a transmission window (transmission for a wide range) at a position where the primary X-ray X1 can be irradiated in a wider area than the partial irradiation during a wide range irradiation. The window 6a) can be moved, and the transmission window (transmission window 6a for a wide range) can be moved to a position where the primary X-ray X1 can be irradiated in a narrower range than the wide range irradiation, which is close to the detector 3 during partial irradiation. Therefore, it is possible to easily perform wide-range irradiation and partial irradiation only by adjusting the position of the transmission window.

The technical scope of the present invention is not limited to each of the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

For example, in each of the above embodiments, a collimator having a transmission window is used as the irradiation range changing mechanism, but an irradiation range changing mechanism capable of changing the irradiation range by using capillaries having different irradiation ranges may be adopted. For example, if the element of interest is an element with a deep analysis depth, a parallel polycapillary is used so that the primary X-rays are parallel on the emission side, and if the element has a shallow analysis depth, the primary X-ray is on the emission side. You may use a focusing type polycapillary that focuses toward the wall surface facing the detector of the sample container.

Further, in the above embodiment, the X-ray fluorescence analyzer is applied to an energy dispersion type fluorescent X-ray analyzer that measures the energy and intensity of X-rays with a wave height analyzer. It may be applied to a wavelength dispersion type fluorescent X-ray analyzer for measuring intensity.

1,21 ... Fluorescent X-ray analyzer, 2 ... X-ray source, 3 ... detector, 4 ... sample container, 4a ... first wall surface, 4b ... second wall surface, 5,25 ... irradiation range changing mechanism, 6 , 26 ... Collimator, 6a ... Wide range transmission window, 6b ... Partial transmission window, 7 ... Collimator moving mechanism, S ... Sample, X1 ... Primary X-ray, X2 ... Fluorescent X-ray

Claims (8)

A sample container that can store samples and
An X-ray source that irradiates the sample with primary X-rays,
A detector that detects fluorescent X-rays generated from the sample irradiated with the primary X-rays, and
It is provided with an irradiation range changing mechanism capable of changing the range of irradiating the sample with the primary X-ray in the sample container.
Partial irradiation in which the irradiation range changing mechanism irradiates the sample at least near the wall surface of the sample container facing the detector with the primary X-rays.
It is possible to change to wide-range irradiation in which the primary X-ray is irradiated to the sample in the sample container in a wider area than the partial irradiation.
The sample container has a first wall surface through which the primary X-rays can be transmitted and a second wall surface through which the fluorescent X-rays can be transmitted.
The X-ray source is arranged adjacent to the first wall surface, and the detector is arranged adjacent to the second wall surface.
A fluorescent X-ray analyzer , wherein the irradiation range changing mechanism irradiates the vicinity of the inner surface of the second wall surface with the primary X-rays at the time of the partial irradiation . A sample container that can store samples and
An X-ray source that irradiates the sample with primary X-rays,
A detector that detects fluorescent X-rays generated from the sample irradiated with the primary X-rays, and
It is provided with an irradiation range changing mechanism capable of changing the range of irradiating the sample with the primary X-ray in the sample container.
Partial irradiation in which the irradiation range changing mechanism irradiates the sample at least near the wall surface of the sample container facing the detector with the primary X-rays.
It is possible to change to wide-range irradiation in which the primary X-ray is irradiated to the sample in the sample container in a wider area than the partial irradiation.
The sample contains light elements as the main component.
When the irradiation range changing mechanism detects at least one of Cd, Sn, Sb, and Ba among the elements in the sample, it switches to the wide range irradiation, and As, Pb, Hg, Br among the elements in the sample. A fluorescent X-ray analyzer characterized in that it is possible to switch to the partial irradiation when detecting at least one of the above . In the fluorescent X-ray analyzer according to claim 1 or 2 .
A collimator in which the irradiation range changing mechanism is arranged between the X-ray source and the sample container and has a plurality of transmission windows capable of transmitting the primary X-rays.
Any one of the plurality of transmission windows is provided with a collimator moving mechanism capable of transmitting the primary X-ray and moving the collimator relative to the X-ray source.
As the transmission window, the collimator is a transmission window for a portion capable of irradiating a region close to the detector with the primary X-ray at the time of the partial irradiation.
A fluorescent X-ray analyzer characterized by having a wide-range transmission window capable of irradiating the sample in the sample container with the primary X-ray in a region wider than the partial irradiation at the time of the wide-range irradiation. .. In the fluorescent X-ray analyzer according to claim 1 or 2 .
A collimator in which the irradiation range changing mechanism is arranged between the X-ray source and the sample container and has a transmission window capable of transmitting the primary X-rays.
A collimator moving mechanism capable of transmitting the primary X-ray and moving the collimator relative to the X-ray source is provided.
The collimator moving mechanism can move the transmission window to a position where the primary X-ray can be irradiated to the sample in the sample container in a region wider than the partial irradiation during the wide range irradiation.
It is characterized in that the transmission window can be moved to a position where the primary X-ray can be irradiated to the sample in the sample container close to the detector in a narrower range than the wide range irradiation at the time of the partial irradiation. Fluorescent X-ray analyzer. The fluorescent X-ray analyzer according to any one of claims 1 to 4 .
The fluorescence range changing mechanism is capable of adjusting the irradiation region of the primary X-ray between the wide range irradiation and the partial irradiation according to the analysis depth of the element of interest among the fluorescent X-rays. X-ray analyzer. The fluorescent X-ray analyzer according to any one of claims 1 to 5 .
A fluorescent X-ray analyzer, characterized in that the sample is rice grains, rice flour, or a fluid solid or liquid. A fluorescent X-ray analysis method in which a sample in a sample container is irradiated with primary X-rays from an X-ray source and fluorescent X-rays generated from the sample are detected by a detector.
A partial irradiation step of irradiating the sample near the wall surface of the sample container facing the detector at least with the primary X-rays.
It has a wide range irradiation step of irradiating the sample in the sample container with the primary X-ray in a wider area than the partial irradiation step .
The sample container has a first wall surface through which the primary X-rays can be transmitted and a second wall surface through which the fluorescent X-rays can be transmitted.
The X-ray source is arranged adjacent to the first wall surface, and the detector is arranged adjacent to the second wall surface.
A fluorescent X-ray analysis method comprising irradiating the vicinity of the inner surface of the second wall surface with the primary X-ray in the partial irradiation step . A fluorescent X-ray analysis method in which a sample in a sample container is irradiated with primary X-rays from an X-ray source and fluorescent X-rays generated from the sample are detected by a detector.
A partial irradiation step of irradiating the sample near the wall surface of the sample container facing the detector at least with the primary X-rays.
It has a wide range irradiation step of irradiating the sample in the sample container with the primary X-ray in a wider area than the partial irradiation step .
The sample contains light elements as the main component.
When detecting at least one of Cd, Sn, Sb, and Ba among the elements in the sample, the process was switched to the wide range irradiation step.
A fluorescent X-ray analysis method comprising switching to the partial irradiation step when detecting at least one of As, Pb, Hg, and Br among the elements in the sample .

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