JPH09269304A - X-ray analytical method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an X-ray analytical method in which various elements can be analyzed precisely by a method wherein a sample which is composed of a fluid is held by a support substrate by making use of its adhesive force, the sample is irradiated with X-rays and its secondary X-rays are analyzed. SOLUTION: An X-ray tube 2 and a beryllium window 3 are attached to an apparatus body 1, a sample holder 4 is installed at the inside, and an analyzing crystal 5 and a detector 6 are arranged and installed at the outside. A viscous sample 7 such as heavy oil or the like is held on a support substrate 8 by making use of the adhesive force of the sample 7 itself and that of the support substrate 8, and the support substrate 8 is supported by the sample holder 4. The inside of the apparatus body 1 is substituted for He gas. In this state, the sample 7 is irradiated with primary X-rays from the X-ray tube 2, and secondary X-rays which are radiated from the sample 7 through the beryllium window 3 are spectrally diffracted by the analyzing crystal 5 so as to be detected by the detector 6.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to sodium (Na), magnesium (Mg) and fluorine (F) contained in viscous petroleum products such as heavy oil, lubricating oil, grease, crude oil, residual oil and other fluids. The present invention relates to an X-ray analysis method that is preferably used when analyzing trace light elements of

[0002]

2. Description of the Related Art Conventionally, as a method for X-ray analysis of a liquid sample, there are (1) a method using an analysis window, (2) a filter paper drip method, and (3) a solidification method for solidifying and analyzing a liquid sample. Are known. The third solidification method was previously proposed by the applicant in Japanese Patent Application No. 6-339435.

In the first method, as shown in FIG. 5, a cylindrical holder 30 whose upper and lower sides are opened is used.
A polymer sheet 31 such as a PP film or a PE film is inserted into the sheet 0, and a liquid sample 32 is loaded into the sheet 31. Then, the lower opening 33 of the holder 30.
Irradiates the sheet 31 with the primary X-ray and detects the secondary X-ray emitted from the sample 32.

In the second method, as shown in FIG. 6, a filter paper 34 having a high absorbability is used, and a liquid sample 32 is dropped on the filter paper 34 to be dried, and the filter paper 34 is adsorbed to the filter paper 34 under vacuum. The sample 32 is similarly analyzed by X-ray.

The third method is to uniformly mix the liquid sample and the solidifying agent while heating and dissolving them. continue,
Place the metal ring on the film spread on the metal plate,
The mixed solution is poured into the inside to be cooled and cured.
After cooling, peel off the film, as shown in FIG.
Form a solid sample 36 with ring 35 remaining around.

Then, as shown in the same figure, an opening 37 is formed at the top.
A holder main body 38 having a hole and a sample holder 41 which is arranged inside thereof and is made up of a hollow cup 40 which is constantly urged toward the opening 37 by a coil spring 39 is used.
And the opening 37 side of the holder main body 38, the solid sample 36 is held in a state where the uniform surface from which the film is peeled off is exposed from the opening 37. After that, the solid sample 36 is similarly subjected to X-ray analysis from the opening 37 of the holder body 38.

[0007]

However, each of the above methods has the following problems. First, according to the first method, the sample 3 is prepared by using the polymer sheet 31 in the holder 30.
Since the secondary X-ray from 2 is absorbed and the sensitivity decreases,
The accuracy of X-ray analysis decreases. In particular, when a light element of Na or less is analyzed, the amount of secondary X-rays from the light element absorbed by the polymer sheet 31 increases, which makes the analysis difficult.

In the second method, when the sample 32 is oily or has a high viscosity, it is difficult to hold the sample 32 on the filter paper 34, and depending on the sample 32, a part of the components is a filter paper. Since the sample concentration is changed by being soaked in the sample 34 or the sample becomes partially nonuniform, accurate X-ray analysis becomes difficult.

The third method is suitable for analysis of a sample such as oil, but since the sample is diluted by the solidifying agent contained in the sample, the sensitivity is reduced accordingly. Moreover, when the solid sample 36 is formed by the sample and the solidifying agent, the solid sample 36 becomes thicker, so that the background component contained in the secondary X-rays from the sample 36 becomes larger and the X-ray also becomes larger.
Reduce the accuracy of line analysis.

Particularly, recently, it has been required to accurately analyze Na at a low level concentration (ppm unit) contained in petroleum products such as heavy oil, lubricating oil, grease, crude oil, and residual oil. It could not be dealt with by any method.

An object of the present invention is to provide an X-ray analysis method capable of accurately analyzing various elements contained in trace amounts in viscous petroleum products and other fluids.

[0012]

In order to achieve the above object, the present invention holds a sample made of a fluid on a support substrate by the adhesive force of the support substrate or the sample itself without impregnating the sample into the support substrate. X-ray analysis of this sample is performed. According to the present invention, an X-ray analysis is carried out by holding a sample made of a fluid in an adhesive state without impregnating the supporting substrate, so that the sample concentration changes and the secondary X Accurate sample analysis without absorption of lines. Therefore, it is suitable for X-ray analysis of trace light elements contained in petroleum products and other fluids.

In one embodiment of the present invention, an adhesive tape is attached to the support substrate, and a sample is applied to the adhesive surface of the adhesive tape. According to this configuration, even if the sample is a highly viscous petroleum product or other low-viscosity fluid,
By being applied to the adhesive surface of the adhesive tape, it is securely held on the supporting substrate.

In another embodiment of the present invention, the supporting surface of the supporting substrate is an uneven surface, and the sample is applied to this supporting surface and held on the supporting surface by the adhesive force of the sample itself. According to this configuration, since the supporting surface having the uneven surface is formed on the supporting substrate, when the sample made of viscous petroleum products or other fluids is applied to this supporting surface, the adhesive force of the sample itself ensures Held in.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The X-ray analysis method of the present invention will be described below with reference to specific examples. FIG. 1 shows an X-ray analysis apparatus used in the present invention. The apparatus is generally used, in which an X-ray tube 2 and a beryllium window 3 are attached to an apparatus main body 1, a sample holder 4 is provided inside, and a spectroscopic crystal 5 is provided outside the main body 1. And the detector 6 are provided.

The sample 7 is made of a viscous fluid such as heavy oil or crude oil. The sample 7 is held on the supporting substrate 8 by utilizing the adhesive force of the sample 7 itself and the supporting substrate 8. The support substrate 8 is supported by the sample holder 4. The inside of the apparatus main body 1 is replaced with He gas in order to suppress noise due to impurities, and in this state, the primary X-rays from the X-ray tube 2 are irradiated toward the sample 7 and the beryllium window 3 is irradiated from the sample 7. Secondary X-rays emitted via the
And the detector 6 detects it.

The supporting substrate 8 is formed by attaching a double-sided adhesive tape 10 on the surface of a main body 9 made of an acrylic plate having a thickness of about 1 mm, and thereby the supporting substrate 8 has an adhesive force. Adhesive surface 1 on the outer surface side of this tape 10
1 is coated with the sample 7. The adhesive tape 10
Has a characteristic that the sample 7 is not impregnated, and does not include an analysis target such as Na, Mg, and F so as not to cause a measurement error. As such a tape 10, various commercially available tapes made of an organic material can be used.

Next, a method of preparing the sample will be described. For example, when performing X-ray analysis on a sample containing a trace amount of Na, after applying the sample 7 to the supporting substrate 8 as described above, H
e Na substitution is measured by substitution. At this time, the analysis line Na
The critical thickness of -Kα is 0.003 mm or more, while the sample 7 made of the fluid has a thickness of 0.003 by coating.
Since it can be reliably attached to the support substrate 8 in a thickness of 3 mm or more, it can be regarded as a bulk sample,
Not affected by thickness. Further, as will be described later in detail, the sensitivity is good and the background is low and the S / N ratio can be increased as compared with the conventional solidification method (Sample 3; when solidified with the mixing ratio of the solidifying agent 1). Moreover, the reproducibility when preparing the sample 7 is also good. Therefore, Na at a low level concentration can be accurately measured.

In addition, the sample 7 is applied to the adhesive surface or the supporting surface of the adhesive tape 10 attached to the supporting substrate 8 by a very simple operation without the sample 7 soaking in or flowing out. The support substrate 8 can be held reliably and in a short time. In addition, the sample 7
X-ray analysis can be performed without drying. For this reason,
It is possible to easily and easily handle the sample 7 when performing X-ray analysis.

Further, by adjusting the coating amount of the sample 7 on the supporting substrate 8 so that the sample 7 does not drip from the supporting substrate 8, the sample 7 is directed downward and is also used for the lower surface irradiation method of irradiating from the lower surface side. it can.

In FIG. 3, the vertical axis shows the X-ray intensity (I) and the horizontal axis shows the calibration curve (Na-Kα) of the sample containing a trace amount of Na with Na concentration (W). The straight line A in the figure is thickness 1
The thickness of the acrylic plate 9 having a thickness of 0.
A calibration curve according to the method of the present invention when an X-ray analysis is carried out with a total thickness of the sample 7 and the supporting substrate 8 of 1.3 mm held by the sample 7 of 3 mm is shown, and the straight line B shows the sample 3: The calibration curve by the conventional solidification method when solidifying with the mixing ratio of the solidifying agent 1 and performing X-ray analysis with a sample thickness of 5 mm is shown as a comparative example.

The calibration curves A and B are as follows: W (Na concentration) = b (reciprocal of sensitivity) × I (X-ray intensity) +
It is obtained by the formula of c. The following Table 1 shows the results obtained by measuring the respective terms b and c of this equation by the measured values based on the experimental results.
The experiment was performed three times under the same conditions for each of the four samples having different Na concentrations, and the average value was obtained.

[0023]

[Table 1]

Comparing the straight lines A and B of FIG. 3 obtained from the above measured values, the calibration B is as described above.
Since the thickness of the sample is large, the c term in the equation of the calibration curve, that is, the background is large, and the b term in the equation, that is, the inclination angle of the calibration curve is large, and the sensitivity is low. On the other hand, it can be understood that the calibration A has a small background (section c) and a good sensitivity (section b). Furthermore, Table 1
As is clear from the above, the accuracy (σ) of the method of the present invention is superior to that of the conventional method. Note that this accuracy
Is the difference between the measured value of each sample and the calibration curve obtained by linearly approximating these measured values.

In each of the above embodiments, for X-ray diffraction analysis of Na contained in petroleum products, for example, Ni, Co, F having wavelength components close to Na are present in both the standard sample and the analytical sample.
It is preferable to add an element such as e to obtain a so-called internal standard. By doing so, the influence of coexisting elements in the sample made of petroleum products can be reduced, and the influence of nonuniformity of the coated surface can be reduced.

FIG. 4 shows another embodiment. In the figure, the support surface 8 having irregularities is formed on the support substrate 8,
The sample 7 is applied to the support surface 13 and held on the support surface 13 by the adhesive force of the sample itself. The outer periphery of the support substrate 8 is formed higher than the support surface 13, and
It is possible to more reliably and satisfactorily prevent the sample 7 applied to the support surface 13 from flowing out. This embodiment also has the same effect as the above-mentioned embodiment using the adhesive tape.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an X-ray analysis apparatus used in an X-ray analysis method of the present invention.

FIG. 2 is a longitudinal sectional view showing one embodiment of the present invention.

FIG. 3 is a calibration curve showing a comparison between the present invention and a conventional example.

FIG. 4 is a vertical cross-sectional view showing another embodiment of the present invention.

FIG. 5 is a vertical cross-sectional view showing a holder provided with a polymer sheet used in a first conventional method.

FIG. 6 is a longitudinal sectional view showing a filter paper onto which an oily sample used in a second conventional method is dropped.

FIG. 7 is a vertical sectional view showing a holder used in a third conventional method.

[Explanation of symbols]

7 ... Sample, 8 ... Support substrate, 10 ... Adhesive tape, 11 ... Adhesive surface. 13 ... Support surface

Claims (3)

[Claims] 1. A sample composed of a fluid is held on a supporting substrate by utilizing the adhesive force of the supporting substrate or the sample without impregnating the supporting substrate, and the sample is irradiated with primary X-rays, Secondary X from the sample
X-ray analysis method for analyzing rays. 2. The X-ray analysis method according to claim 1, wherein the support substrate has an adhesive tape mounted on the main body, and the sample is applied to the adhesive surface of the adhesive tape. 3. The X-ray analysis method according to claim 1, wherein the support surface of the support substrate is formed as an uneven surface, the sample is applied to the support surface, and the sample is held by the adhesive force of the sample itself.