JPH04204362A - Quantitative measurement of element - Google Patents

Abstract

PURPOSE:To obtain a measured value without preliminary measurement by obtaining the wavelength of each element from the spectral peak height of the each element and, when there is an interfering element, subtracting the value obtained by multiplying the interfering element by a correction factor from the element subjected to the interference. CONSTITUTION:A sensitivity factor and a correction factor for each element, necessary in data processing, are first determined. The measuring points are then set at the positions, I, K, of wavelength centers of peaks D1, D2. At the respective measuring points, fluorescent X ray intensities BI, DK are measured. Temporary concentrations of elements a.b are thus obtained by fundamental parameter method (FP method), using BI, DK, so that a true concentration of the element 'a' is obtained. In the case when mutural interferences between the elements a.b are not ignorable, with the true concentration as a first approximate value, the value obtained by multiplying a correction factor for the element 'b' due to the element 'a' by the true concentration is subtracted from the concentration of the element 'b'. The resultant value is substituted in a predetermined formula, so that a second approximate value for the element 'a' is obtained. Similar successive approximate calculation is contitued.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for quantifying elements using the fundamental parameter method (<FP method) in fluorescence X& analysis.

(Prior art) In the FP method in fluorescent X-ray analysis, instead of using the same type of sample as the sample to be measured, it is possible to use a completely different type of substance from the sample to be measured as long as it contains the element to be quantified. There are advantages that can be achieved. The FP method is as follows. Since the fluorescent X-ray intensity of the component elements can be theoretically calculated from the elemental composition of the sample, the fluorescence Assuming that the X-ray intensity is 1, I
o/I is the sensitivity coefficient for the element of the X-ray fluorescence spectrometer used. By measuring the fluorescent X-ray intensity of the target element for a sample to be measured and multiplying that value by the above-mentioned sensitivity coefficient, the theoretical intensity of the fluorescence x4il of the target element for that sample is determined. On the other hand, assuming the quantitative value of the target element in the sample to be measured, calculate the theoretical intensity of the fluorescent X-ray intensity, compare it with the theoretical intensity obtained from the above measurement, correct the quantitative value, recalculate the theoretical intensity, The same operation is repeated until the measured theoretical strength and the calculated theoretical strength match. This is the outline of the FP method.

In such quantitative analysis methods, if other elements coexist in the sample that appear close to the peak of one element to be quantified in the fluorescent X-ray spectrum, the tail of the peak of that element may be distorted. The height of the center of the peak of the element to be quantified overlaps with the peak of the element to be quantified, and the height of the center of the peak of the element to be quantified becomes higher in the measurement, and since what is determined by the FP method is the net peak height, the concentration may be mistaken as being higher than the actual concentration. If there are peaks that are close to each other, it is necessary to perform correction.

In fluorescent X-ray analysis, the above-mentioned correction is easy when scanning the entire range of the fluorescent X-ray spectrum to obtain data for the entire spectrum. Measuring the intensity of emitted fluorescent X-rays takes a long time to complete. For this reason, a method is used in which several measurement points are appropriately set on the spectrum depending on the sample components, and the intensity of fluorescent X-rays emitted from the sample is measured only at those points. This method enables simultaneous measurement of ゛ at these multiple measurement points and shortens the measurement time, but since the peak profile of each component element on the spectrum is unknown, if the tails of the peaks overlap, it may be due to overlap. The impact is not directly known. For this reason, conventional correction methods such as Hiro have been used.

Since the component composition of the sample is known by qualitative analysis prior to quantitative analysis, the peak center of each quantitative target element and its rising point are set as measurement points. Assuming that the spectrum of the sample is as shown in FIG. 3, an attempt is made to quantify the element exhibiting the peak P1. In 2\, P2 is the peak of another element, and its tail overlaps with peak P1. The center point of the peak P1, the rising point H, and the falling point J are set as measurement points. In the figure, heights A)l, Bl, and CJ are directly measured. From these measured values, the true height of peak P1 is designated as BP in the diagram, and by multiplying this by the sensitivity coefficient described above, the concentration of element a to be quantified is determined by the FP method.

This method assumes that the tail of peak P2 is a straight line CFA, and the actual shape of the tail of P2 is as shown by the dotted line, so when BF is the true height of peak P1, the peak intensity is After a while, it will have an error of only FG.

In other conventionally used methods, the presence of element S, which overlaps the peak of element a to be quantified in Figure 3, is known through qualitative analysis, etc., so the peak does not contain element a-, but contains element S. The peak profile of the element S is measured using a standard sample, and the intensity of the tail portion of the peak P2 of the element S at one point in FIG. 3 is determined as a function of the peak height DK of the element S.

Let this function be α(DK), measure the spectral intensity at point I for the sample to be analyzed, and calculate the true peak height BG of element a by BG=B I−α(DK)・DK Although this method is accurate, it is necessary to perform the above-mentioned measurement on elements with peaks that overlap with the peaks of the target element for quantification, and a special standard sample is required. The advantage of the FP method, which is that it is not restricted by the type of data, is lost, and the analysis work becomes complicated. ``(Problem to be solved by the invention) The present invention aims to provide an elemental determination method using spectral analysis that allows accurate quantitative analysis without the troublesome preliminary measurements as described above. .

(Means for solving the problem) Determine the peak height at the center of the fluorescent X-ray peak of element a to be quantified and the peak center height of element A whose tail portion overlaps with the peak center of element εt. element a, by the FP method using the above measurement results as is.
Find the provisional concentrations X and Y of element b, multiply the above quantitative value Y of element S by a coefficient of 7:, and calculate the true quantitative value W of element a as w = x - Y... ...I decided to find it as (1).

(Function) The coefficient ":, : in the above formula (1) is the ratio of the intensity at the center of the spectrum of element a at the tail of the fluorescence X-ray spectrum peak of element A to the intensity at the center of the spectrum peak of element A. Therefore, the characteristics between the elements have been measured in advance, and the data has been accumulated as known data (for example, J
IS G1256), it is possible to determine and use the data from these data. Therefore, it is not necessary to actually measure the peak profile of each element in the sample to be measured, and quantification can be performed while correcting the influence of other elements without performing wavelength scanning.

(Example) An example of the present invention will be described using FIGS. 1 and 2. FIG. 1 shows a fluorescent X-ray spectrum, where peak P1 is the peak of element a, P2. P3 is the peak of element S.

Although element b is an interfering element with respect to element a, the target element for quantification may be only a or both a and b. For element a, there is no PIL peak in the measurement wavelength range, so the only way to quantify it is to measure the height of peak P1, but for element A, PIL does not have a peak in the measurement wavelength range. Since the two peaks of P3 are within the measurement wavelength range, either peak may be used for quantitative determination.

If the overlap of the tail portion of peak P1 at the center position of peak P2 cannot be ignored, it is sufficient to perform quantification using peak P3. In that case, the influence of the tail portion of P2 on the quantification of element a can be corrected by This can be done using measured values.

A case will be described in which the elements a and b are quantified using the Nozu peaks PL and P2. FIG. 2 is a flowchart of the measurement operation in this case. First, set the sensitivity coefficient and correction coefficient ′:: for each element necessary for data processing (a)
Then, the measurement points are set at the peak PL in Fig. 1, and the center wavelength value I of P2.
I, K (b), and the fluorescent X-ray intensity B1 at each measurement point. Measure DK (c), find the tentative concentration of elements a-b by the FP method using Bl and DK (d), and find the true concentration W of element a as W = X a-Y... . . . (2) is determined (e), and for the element, the upper idY is used as the true concentration and the quantitative result is displayed (go) to end the analysis operation. In 21, regarding element A, the interfering effect of element a is treated as negligible. Element a.

b When mutual interference cannot be ignored (well, above (e))
In the steps up to, using W as a first approximation, and using the correction coefficient y' for element a of element a, the concentration of element a is determined as Y'=Y-Z'W, and this Y' is calculated using equation (3) You can calculate the second approximation value of element a by inserting it in place of Y in Therefore, if the center position of P3 is selected as the measurement point instead of P2, the concentrations of elements a and b can be determined without the need for successive approximation calculations as described above. In this case, the measurement point is 1 in Figure 1.
．． Select the L point and create a calibration curve for each element using the measured values at the L point. The concentration Y of the element is determined from the measured value EL at point L using a calibration curve. Inserting this Y into the equation (2) above, the concentration of element a is determined. Correction coefficient′″′ in this case
: is, needless to say, a correction coefficient based on the peak P3.

(Effects of the Invention) The present invention converts the measured value of the spectrum into the concentration value of the element and then performs a correction calculation for the interfering element, thereby making it possible to perform correction using known data without preliminary measurements. This makes it possible to simplify the fluorescence X&1 analysis work.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the method of the present invention, FIG. 2 is a flowchart of an embodiment of the method of the present invention, and FIG. 3 is an explanatory diagram of a conventional example. Agent Patent Attorney Kosuke Agata

Claims (1)

[Claims] In the fluorescent X-ray analysis method, the height of each peak is measured using the spectral peak center of each element on the fluorescent X-ray spectrum as the measurement point, and the concentration of each element is determined from the height of each peak by the FP method, When there is an interfering element that exhibits a peak that overlaps with the spectrum of a certain element, the concentration of the interfering element obtained above is used as the provisional concentration, and the value obtained by multiplying the concentration of the interfering element by the correction coefficient is calculated as the concentration of the interfering element. An elemental determination method characterized by subtracting from the provisional concentration to obtain the true concentration of the element that is being interfered with.