JP2000065764A - X-ray fluorescence analysis of liquid sample - Google Patents

Abstract

PROBLEM TO BE SOLVED: To highly accurately and quantitatively determine a micro-wt. element and a light element by correcting the X-ray fluorescence intensity of the light element in a liquid sample measured by dropping the liquid sample on an X-ray transmissible film by the quantitative value and X-ray fluorescent intensity of the micro-wt. element. SOLUTION: A liquid sample 11 wherein a micro-wt. element (i) heavier than S(sulfur) and a light element (j) lighter than S is put in a sample cell 10 to be set to a sample position 3 and irradiated with X-rays 2 in air. Then, the X-ray fluorescence intensity Ii1 is measured by a technique I and the concn. C1 thereof is determined. Next, an X-ray permeable film 15 on which a sample liquid droplet 11A is dripped is set to the sample position 3 and an X-ray path part is evacuated to irradiate the sample liquid droplet 11A with X-rays 2 to measure the X-ray fluorescence intensity of the element by a technique II and the X-ray fluorescence intensities Ii2, Ij2 of both elements (j), (j) are obtained. A correction coefficient gi (t) is obtained form the quantitative value C1 and fluorescent X-ray intensity Ii2 of the micro-wt. element (i) and the X-ray fluorescence intensity Ij2 of the light element (j) is corrected based on this to determine the light element (j).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of irradiating a liquid sample with X-rays and performing a quantitative analysis of the liquid sample based on the fluorescent X-rays emitted from the liquid sample. Related to analysis method.

[0002]

2. Description of the Related Art FIG. 2 schematically shows a general configuration of an apparatus for performing X-ray fluorescence analysis.
1 is an X-ray source that generates X-rays 2, 3 is a sample, 4 is an X-ray detector that detects fluorescent X-rays 5 generated in the sample 3 by irradiating the sample 3 with the X-rays 2, and 6 is an AD converter. , 7 is a multi-channel pulse height analyzer, and 8 is a computer.
In the apparatus configured as described above, the sample 3 is irradiated with the X-rays 2 emitted from the X-ray source 1, the fluorescent X-rays 5 emitted from the sample 3 are detected by the X-ray detector 4, and the output thereof is output. Is input to the multi-channel analyzer 7 via the AD converter 6 to obtain an energy spectrum. The energy spectrum is read by the computer 8 as spectral data of the fluorescent X-ray energy, and the element contained in the sample 3 and its concentration can be determined based on the position and height of the peak in the spectral data.

When the sample 3 is a liquid,
Conventionally, as shown in FIG. 3, a liquid sample is subjected to a certain treatment (pre-treatment) to obtain a predetermined sample form, and the pre-treated liquid sample is irradiated with X-rays to perform a predetermined measurement. Had to do it.

[0004] That is, the first method (pretreatment 1) is a sample form in which a liquid sample 11 is accommodated in a sample cell 10 having an X-ray transparent bottom 9 as shown in FIG.
The measurement is performed by setting the sample cell 10 containing the liquid sample 11 at the position of the sample 3 in FIG. Here, the sample cell 10 includes a cell outer frame 12 and a cell inner frame 13.
And an X-ray permeable film 14 sandwiched between the outer frame 12 and the inner frame 13 and closing the lower side of the cell inner frame 13. A part of the X-ray permeable film 14 is Is constituted. In addition, as such a sample cell 10, for example, Japanese Patent Publication No. 54-20360
Is disclosed in Japanese Patent Application Laid-Open Publication No. HEI 9-203 (1995).

The second technique (preprocessing 2) is shown in FIG.
As shown in (B), the liquid sample 11 is dropped on the upper surface of the X-ray transparent thin film 15, and when the liquid sample 11 is an aqueous solution, measurement is performed after drying. When the liquid sample 11 is oil, an oil film is formed. The X-ray permeable film 15 on which the dried or oil film liquid sample 11 is placed is set at the position of the sample 3 in FIG. In FIG. 3B, reference numeral 11A denotes a sample droplet.

The third technique (pre-processing 3) is shown in FIG.
As shown in (C), the liquid sample 11 is dropped on the filter paper 16, and the filter paper 16 on which the liquid sample 11 is dropped is set at the position of the sample 3 in FIG. In FIG. 3B, reference numeral 11B denotes a sample droplet.

[0007]

However, the above-mentioned 1)
Each of the three methods (pre-processing 1 to 3) has advantages and disadvantages, and none of them can be said to be complete methods (pre-processing). That is, in the method 1 (pretreatment 1), that is, the method using the sample cell 10, the upper and lower surfaces of the liquid sample 11 in the sample cell 10 are flattened, and the position such as the distance to the X-ray tube 1 and the X-ray detector 4 Since the relationship is accurate, the reproduction accuracy (reproducibility) is excellent.

However, in the above-mentioned method 1 (pretreatment 1), it is difficult to evacuate the space where the sample cell 10, the X-ray tube 1, the X-ray detector 4 and the like are arranged during measurement. Part of the X-rays and fluorescent X-rays are absorbed by the air in the X-ray path between the cell 10 and the X-ray tube 1 and the X-ray detector 4, so that Al (aluminum) or Si
There is a disadvantage that the detection sensitivity of light elements such as (silicon) is not good. In addition, since the background due to scattering is high, there is also a disadvantage that the detection limit of heavy elements (elements heavier than S (sulfur), hereinafter referred to as “trace heavy elements”) contained in the liquid sample 11 in a trace amount is poor.

Further, method 2 (pre-processing 2), that is, X
In the method using the X-ray transparent film 15, the space in which the X-ray transparent film 15, the X-ray tube 1, the X-ray detector 4 and the like are arranged can be evacuated during the measurement. There is an advantage that the sensitivity is high. In addition, since the background due to scattering is low, there is an advantage that the detection limit of trace heavy elements is good.

However, in the above-mentioned method 2 (pre-processing 2), the reproducibility is poor because the state of the droplet 11A after drying is not always constant and it is difficult to control the oil film thickness. There are drawbacks.

Then, method 3 (pre-processing 3), that is,
In the method using the filter paper 16, the reproducibility of the sample state is high.
Although it is inferior to the case of (pre-processing 1), it is better than the case of method 2 (pre-processing 2). And at the time of measurement, filter paper 1
6, the space in which the X-ray tube 1, the X-ray detector 4 and the like are arranged can be evacuated. However, since fluorescent X-rays are absorbed by the filter paper 16, the measurement sensitivity of light elements can be reduced by the method 2 ( Lower than pre-processing 2). Further, there is a disadvantage that the background is higher than that of the method 2 (pre-processing 2) due to the thickness of the filter paper 16, and the detection limit of the trace heavy element is lower than that of the method 2 (pre-processing 2).

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has as its object to measure the fluorescence of a liquid sample capable of accurately and reproducibly quantifying light and trace elements in the liquid sample. It is to provide an X-ray analysis method.

[0013]

According to the present invention, a liquid sample is irradiated with X-rays, and a quantitative analysis of the liquid sample is performed based on fluorescent X-rays emitted from the liquid sample. X-ray fluorescence analysis of a liquid sample, the quantitative measurement of the element obtained when the liquid sample is contained in a sample cell having an X-ray permeable bottom and measurement, and the X-ray transmission of the liquid sample The liquid sample obtained by dropping the liquid sample on the X-ray permeable film, based on the fluorescent X-ray intensity of the element obtained when the sample is dropped on the transparent film and measured. The fluorescent X-ray intensity of the light element or trace heavy element is corrected, and the light element or trace heavy element is quantified based on the corrected fluorescent X-ray intensity (claim 1).

In the above invention, the method using the sample cell and the method using the X-ray transmissive film are combined. However, the method using the sample cell and the method using filter paper may be combined. The technique and a technique using an X-ray transparent film may be combined.

That is, quantitative values of elements obtained when a liquid sample is accommodated in a sample cell having an X-ray permeable bottom and measured, and obtained when a liquid sample is dropped on a filter paper and measured. Based on the fluorescent X-ray intensity of the element, the fluorescence X of the light element or trace heavy element contained in the liquid sample obtained when the liquid sample is dropped on a filter paper and measured.
The linear intensity may be corrected, and the light element or the trace heavy element may be quantified based on the corrected light intensity (claim 2). In addition, the element obtained when the liquid sample is dropped on the filter paper and measured is measured. Based on the quantitative value and the fluorescent X-ray intensity of the element obtained when the liquid sample was dropped on the X-ray permeable film and measured, X was added to the liquid sample dropped on the X-ray permeable film. To correct the fluorescent X-ray intensity of the light element or the trace heavy element contained in the liquid sample obtained when measuring by irradiating a ray, and to quantify the light element or the trace heavy element based on this. (Claim 3).

In any of the above inventions, the light element and the trace heavy element in the liquid sample can be accurately determined.

[0017]

Embodiments of the present invention will be described with reference to the drawings. One embodiment of the method for X-ray fluorescence analysis of a liquid sample according to the present invention will be described with reference to FIG. The form of the device and the sample used in the present invention are not different from those shown in FIGS. 2 and 3, respectively.

Now, it is assumed that an element i heavier than S (sulfur) and an element j lighter than S are present in the liquid sample 11. First, as shown in FIG. 3A, a predetermined amount of a liquid sample 11 is stored in a sample cell 10, and the sample cell 10 is set at a sample position (position indicated by reference numeral 3) in FIG. The liquid sample 11 is irradiated with X-rays 2 to perform measurement by the method 1 (pre-processing 1) (step S1). This method 1
The relationship between the fluorescent X-ray intensity and the concentration for each of the elements i and j in (Pretreatment 1) is expressed as follows. I _i = I _i ¹ = f _i (C _i ) (1) I _j ¹ = f _j (C _j ) (2) where I _i ¹ : Method 1 of element i (preprocessing 1) Is the fluorescent X-ray intensity C _i : the concentration of element i.

Since the element i is an element heavier than S, it can be measured in the air, and its concentration can be determined by the above equation (1), so that it is quantified (step S2). Note that the same expression (2) as the expression (1) holds for the element j. However, since the element j is a lighter element than S, measurement in the air is impossible, and I _j ¹ is Can not. Therefore, at this stage, C _j cannot be determined.

Next, as shown in FIG. 3B, the liquid sample 11 is dropped on the X-ray permeable film 15, and
After the drying of 1, the X-ray permeable film 15 is set at the sample position (position indicated by reference numeral 3) in FIG. 2, the X-ray path is evacuated, and the liquid sample 11A is irradiated with X-rays 2 and the method 2 The measurement by (preprocessing 2) is performed (step S3). By this measurement, the fluorescent X-ray intensity I _i ² of the element i and the fluorescent X-ray
The line intensity I _j ² is obtained (step S4).

Here, the following relationship is established between the intensities of technique 1 (pre-processing 1) and technique 2 (pre-processing 2). I _i ² = g _i (t) · I _i ¹ (3) I _j ² = g _j (t) · I _j ¹ (4) where I _i ² : Method 2 of element i (before Measured fluorescent X-ray intensity in process 2) t: thickness of liquid sample 11A in method 2 (pre-process 2)

Since both I _i ¹ and I _i ² can be obtained by measurement, the method 2 can be obtained from the above equation (3).
The thickness t of the liquid sample 11A in (Pre-processing 2) can be obtained, the correction coefficient g _i (t) is obtained (step S5), and t is obtained.

The corrected I _j ¹ is obtained by applying the obtained t to the equation (4). In addition,
G _j (t) in the equation (4) is a correction coefficient for the light element j. Then, by applying the obtained I _j ¹ to the equation (2), the concentration C _j of the light element _j is obtained (step S6).

As described above, in the method of X-ray fluorescence analysis of a liquid sample in the above embodiment, light elements which were difficult to measure in method 1 (pretreatment 1)
Quantification can be performed accurately and with good reproducibility. In the method 2 (pretreatment 2) in which the liquid sample 11 is dropped on the X-ray transparent film 15 and the measurement is performed, not only can the measurement atmosphere be evacuated but also the liquid sample 1 can be evacuated.
Since scattering by 1A is reduced, not only light elements,
Measurement sensitivity is also improved for heavy elements. Therefore, according to the method of X-ray fluorescence analysis of the liquid sample, the liquid sample 11
The precision and reproducibility of quantification of heavy elements contained only in trace amounts can be improved.

According to the present invention, in the above embodiment, the measurement by the method 1 (pre-processing 1) and the measurement by the method 2 (pre-processing 2) are combined, and the liquid sample 11 is placed on the X-ray permeable bottom 9. The quantitative value C _{1 of the} element obtained when the sample is contained in the sample cell 10 and the fluorescence X of the element obtained when the liquid sample 11 is dropped on the X-ray transparent film 15 and measured. Fluorescent X-ray intensity of light element or trace heavy element contained in liquid sample 11 obtained when liquid sample 11 is dropped on X-ray permeable film 15 and measured based on line intensity I _i ² Although I _j ² was corrected and the light element or the trace heavy element was quantified based on this, the present invention is not limited to this. Measurement by method 1 (pre-processing 1) and method 3 (pre-processing 1) 3) Measurement may be combined with The measurement of Method 3 (Preprocessing 3) and the measurement of Method 2 (Preprocessing 2) may be combined. In any of these cases, it goes without saying that the same effects as those of the above-described embodiment can be obtained.

[0026]

According to the method of X-ray fluorescence analysis of a liquid sample of the present invention, a light element and a trace heavy element in a liquid sample can be quantified with high accuracy and high reproducibility.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an example of a method of X-ray fluorescence analysis of a liquid sample according to the present invention.

FIG. 2 is a diagram showing a schematic configuration of an apparatus for performing the X-ray fluorescence analysis method for the liquid sample.

FIG. 3 is a diagram showing a processing mode of a liquid sample.

[Explanation of symbols]

2 ... X-ray, 5 ... Fluorescent X-ray, 9 ... X-ray transparent bottom, 10
... sample cell, 11, 11A, 11B ... liquid sample, 15 ...
X-ray transparent film, 16 ... filter paper.

Claims (3)

[Claims] 1. A method for X-ray fluorescence analysis of a liquid sample, comprising irradiating a liquid sample with X-rays and quantitatively analyzing the liquid sample based on fluorescent X-rays emitted from the liquid sample at the time. A quantitative value of an element obtained when a sample is accommodated in a sample cell having an X-ray permeable bottom and measured, and the element obtained when a liquid sample is dropped and measured on an X-ray permeable film The fluorescent X-ray intensity of the light or trace heavy elements contained in the liquid sample obtained by dropping the liquid sample on the X-ray transparent film and measuring based on the fluorescent X-ray intensity of And X-ray fluorescence analysis of a liquid sample, wherein the light element or the trace heavy element is quantified based on this. 2. The method according to claim 1, wherein the liquid sample is irradiated with X-rays, and a quantitative analysis of the liquid sample is performed based on fluorescent X-rays emitted from the liquid sample. The quantitative value of the element obtained when the sample is contained in a sample cell having an X-ray transparent bottom and measured, and the fluorescence X of the element obtained when the liquid sample is dropped on a filter paper and measured. Based on the linear intensity, the fluorescent X-ray intensity of the light element or the trace heavy element contained in the liquid sample obtained when the liquid sample is dropped on the filter paper and measured is corrected, and based on this, A fluorescent X-ray analysis method for a liquid sample, wherein a light element or a trace heavy element is quantified. 3. A method for X-ray fluorescence analysis of a liquid sample, wherein the liquid sample is irradiated with X-rays and quantitative analysis of the liquid sample is performed based on fluorescent X-rays emitted from the liquid sample. Based on the quantitative value of the element obtained when the sample is dropped on the filter paper and measured, and the fluorescent X-ray intensity of the element obtained when the liquid sample is dropped on the X-ray permeable film and measured. And correcting the fluorescent X-ray intensity of the light element or the trace heavy element contained in the liquid sample obtained by irradiating the liquid sample dropped on the X-ray transparent film with X-rays and measuring it. X-ray fluorescence analysis of a liquid sample, characterized in that the light element or the trace heavy element is quantified based on the following.