JPH0690133B2 - Optical emission spectroscopy Spectral line selection support device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an apparatus for assisting in the selection of spectral lines in emission spectroscopy.

B. Prior art Optical emission spectroscopy is an analytical method for qualitatively and quantitatively determining the elements present in a sample substance. When energy is externally supplied to the sample substance by some means, each element present in the sample substance emits a unique light (spectral line). Since the emitted spectral line has a specific center wavelength for each element, it is possible to obtain information on the identification and quantification by observing the spectral line of each element.

As is well known, there are multiple spectral lines emitted for each element. Further, in general, a substance is rarely composed of only a single element, and in many cases a plurality of elements coexist.

Therefore, when the sample substance is made to emit light, many spectral lines are emitted, and tens to hundreds of thousands of spectral lines are observed in the sample substance having a complicated composition.

Extraction of these spectral lines is performed in the spectroscopic / photometric unit, but there is a problem of spectral interference in which the spectral lines of the target analytical element interfere with the spectral lines of other coexisting elements.

That is, as shown in FIG. 12, the center wavelength of the spectrum line X ₀ of the analysis element is λ _0X , and the spectrum lines Y ₀ and Z _{0 of the} coexisting element are shown.
If the center wavelength of λ is _0Y or _λ0Z , the wavelength distance | λ _0X −λ
_{Since 0Y} |, | λ _0X −λ _0Z | is small, the spectral lines Y ₀ and Z ₀ of the coexisting element are superimposed on the spectral line X ₀ of the analytical element.

Spectral line of analytical element itself at center wavelength λ _0X
The intensity of X ₀ is P ₀ , and the spectral line resulting from the above superposition
When 'the intensity of P _0' X ₀ and, P ₀ 'is increased than P _0, the intensity P ₀ of the result of the superposition' spectral lines X ₀ of 'is observed incorrectly as spectral lines of the analysis element, An error of P ₀ −P ₀ ′ occurs.

This is the spectral interference, and the central wavelength λ _0X that causes the spectral interference.
Regarding, the coexisting element is referred to as an interfering element against the analytical element.

The degree of spectral interference due to this interfering element increases as the inter-wavelength distance decreases and the intensity of the interfering element increases. If the center wavelength of the interfering element coincides with the center wavelength of the analytical element, the influence of the interference is further magnified and the error of P ₀ −P ₀ ′ is also increased.

However, in the case of the spectrum line X ₁ at the center wavelength λ _1X of the element to be analyzed, the distance | λ _1X between the center wavelength λ _1X and the center wavelengths λ _1Y and λ _1Z of the spectrum lines Y ₁ and Z ₁ of the coexisting element −λ
_{Since 1Y} |, | λ _1X −λ _1Z | is large, the spectral interference does not occur or it occurs only slightly.

If there is no spectral interference, the observed intensity P ₁ of the spectrum line X ₁ may be treated as the correct intensity at the center wavelength λ _1X of the analytical element itself. Spectral lines of other elements
The same applies when the strengths of Y ₁ and Z ₁ are sufficiently small.

Therefore, in the spectroscopic analysis, it is sufficient to select a spectral line having a wavelength that does not cause spectral interference with the analysis element.

C. Problems to be Solved by the Invention In order to accurately select an appropriate wavelength in spectroscopic analysis, there are multiple spectral lines of each element as described above, and
Due to the large number of elements contained in the sample substance, it is inevitable that a huge amount of back data is required.

For example, if the number of elements to be measured is 70 and the number of spectral lines of individual elements is 10, spectral interference can occur mutually, so the data items are 70 × 10 × (70-1) ≈48,000. .

However, in the past, when selecting a wavelength that does not cause spectral interference from the enormous back data,
Since it relies only on the experience of the analyst, there is a problem that it takes a lot of time and, in addition, a selection error often occurs.

The present invention has been made in view of such circumstances, and an object thereof is to make it possible to easily and accurately select a spectral line having a wavelength that does not cause spectral interference or is least likely to cause spectral interference.

D. Means for Solving the Problems The present invention has the following configuration in order to achieve such an object. In order to help understanding, reference numerals used in the examples described later are also described.

That is, the emission spectrum analysis spectral line selection support device of the present invention is capable of causing spectral interference for each of the plurality of target spectral lines Mi for each measurement target element Ai (i = 1, 2, ...). Interference line N of the coexisting element Aj (j = 1,2 ...)
ij and the target spectral line Mi between wavelengths aij and the intensity of the interfering spectral line Nij per unit concentration of coexisting element Aj (conversion unit concentration) database 3 for registering back data of bij, and actual concentration of coexisting element Aj Means to input cj (keyboard 5
Etc.) and the inter-wavelength distance aij, the converted unit concentration bij and the actual concentration cj, the interference degree I (i, j) which is the degree of the spectral interference received by each target spectral line Mi is calculated, and each target spectral line is calculated. The recommended value S (i) that is the sum of the interference degree I (i, j) for each wavelength λi of Mi is calculated, and these recommended values S (i) are calculated.
Computing means (microcomputer 4 etc.) for retrieving (i = 1, 2 ...) In the order of size, and display means (display 6 etc.) for displaying the recommended values S (i) according to the order of the sorting. It is characterized by having.

E. Action The action of the configuration of the present invention is as follows.

That is, the recommended value S (i) (i = i, j) (i = 1,2 ..., j = 1,2 ...) Summed up for each wavelength λi of each target spectral line Mi 1,2 ...) are sorted in order of size, and the recommended value S (i) (i = 1,2
(...) is displayed, the analyst can simply select the target spectral line M _MIN of the wavelength λ _MIN that does not cause spectral interference or is the most unlikely to cause spectral interference, only by looking at the displayed recommended value S (i) column. Can be done easily and accurately.

F. Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

First, the “interference degree” as an index showing the degree of spectral interference of the coexisting element with respect to the spectral line of a certain wavelength of the analysis element will be described.

That is, as shown in FIG. 1, the central wavelength of an arbitrary target spectrum line Mi of a plurality of spectrum lines Mi (i, 1, 2, ...) Of an analysis element is λi. Of the plural coexisting element spectral lines, the spectral lines of the individual interfering elements that are affected by the reference wavelength distance ± λ _T on the long wavelength side and the short wavelength side from the central wavelength λi are Nij (j = 1, 2 ...), and the central wavelength of the interference spectrum line Nij is represented by λij.

Here, in the suffix “ij”, “i” corresponds to the target spectrum line Mi, and “j” corresponds to the type of interfering element having a spectrum line capable of spectral interference with the target spectrum line Mi. and it is (the same applies hereinafter. when the first view, with respect to the spectral line Mi analysis elements, three spectral lines Nij of interfering _{elements, Ni, j +1, Ni,} j +2 are shown).

Then, the difference between the center wavelength Mλij of the interference spectrum line Nij and the center wavelength λi of the target spectrum line i is calculated as the inter-wavelength distance aij.
It is defined as

aij = λij−λi ... Aij takes a positive value when the interference spectrum line Nij exists on the long wavelength side, and takes a negative value when it exists on the short wavelength side.

The intensity of the interference spectrum line Nij per unit concentration of the coexisting element is converted into the intensity per unit concentration of the analytical element (this is referred to as the conversion unit concentration), and bij is the actual concentration of the coexisting element.

Then, the degree of interference I (i, j) is defined by the function of aij, bij, cj, I (i, j) = f (aij, bij, cj).

Various equations can be considered as the equation of the function f. For example, f = I (i, j) = cj.bij / | aij | ... can be set. This equation shows that the degree of interference (spectral interference) will be proportional to the actual concentration cj of the coexisting element,
It is also assumed that it will be inversely proportional to the absolute value of the inter-wavelength distance | aij |.

As another equation of the function f, for example, | aij | ² is adopted instead of | aij | when the wavelength resolution of the spectroscopic / photometric unit is low, or | aij | ^{1 /} when the resolution is sufficiently high. ² may be adopted. If the sensitivity of the spectroscopic / photometric unit is low,
If you use cj ² instead of cj, or if the sensitivity is sufficiently high, cj
In some cases, j ^1/2 is adopted.

Back data, which is the basis for supporting the selection of spectral lines of wavelengths that do not cause spectral interference in emission spectroscopy, that is, the basis for calculating each interference degree I (i, j) depending on the sample substance An example of such back data is shown in FIG.

This back data is obtained by measuring the inter-wavelength distance aij within the reference wavelength distance ± λ _T of each coexisting element with respect to the center wavelength λi of each target spectral line Mi measured by the spectroscopic / photometry unit, and the converted unit concentration bij of each coexisting element, It is registered in a spreadsheet format.

That is, in FIG. 2, there are elements A ₁ , A ₂ , A ₃ ... Aj.
When the element A ₁ is an analytical element, the central wavelengths λ ₁ , λ _2, ... Of a plurality of spectral lines Mi (i = 1, 2 ...) Of the analytical element A ₁
For λi, a plurality of coexisting elements A ₂ , A ₃ ‥ Aj ‥‥
Distance between wavelengths aij and conversion unit concentration bij (i = 1,2
.., j = 1,2 ...) and is a list.

For example, the spectral line M ₁ of the central wavelength lambda ₁ in the analysis element A _1, the center wavelength spacing of coexisting elements A _2, a ₁₂ translation unit concentration, respectively, b _12, the wavelength distance between coexisting elements A _3, in terms of units The concentrations are a ₁₃ and b ₁₃ , respectively, the interwavelength distance of the coexisting element Aj and the conversion unit concentration are aij and bij, respectively.

In the case of the central wavelength λ ₂ and the coexisting element A ₃ , a ₂₃ , b
₂₃ and a ₂₃ ', b ₂₃ ' may have two or more inter-wavelength distances and reduced unit concentrations. Also each ai
In some cases, j and bij can take the value 0, and each aij takes a positive value on the long wavelength side and a negative value on the short wavelength side. If it is 0, it may be left blank in the spreadsheet.

BEC (Background Equivalent Concent) at the bottom of Fig. 2
ration), as shown in FIG. 3, the background intensity P _B and the detected intensity P _{S based} on the background.
Is the concentration c _BEC when P _S = P _B.

As can be seen from the comparison between c _BEC1 and c _BEC2 , the smaller the BEC value _βi , the lower the concentration that can be detected (even a trace amount can be detected). This BEC value βi (i = 1,2 ...)
Corresponds to the reciprocal of the sensitivity of the spectral line Mi.

Since any i-th spectral line Mi in an analysis element can be interfered with by the spectral lines Nij of multiple types of coexisting elements, the total effect of the interference is the degree of interference I (i , j). If this sum is expressed as S (i), Becomes

Since the value of S (i) is an index of the order of selection of the spectral line having a wavelength that does not cause spectral interference, S (i) will be referred to as a recommended value.

The recommended value S (i) represents the total sum of interference. The larger the value, the stronger the interference, and the smaller the value, the less interference. Therefore, as the recommended value S (i), the smaller the value, the spectral interference. It means that it is advantageous to avoid. If the recommended value S (i) is 0, it means that there is no interference.

Corresponding to FIG. 2, FIG. 4 shows a plurality of spectral lines Mi (i = 1,2) of the analytical element A ₁ when the element A ₁ is the analytical element.
..) at each center wavelength λ ₁ , λ _2, λi,
A plurality of coexisting elements A ₂ , A ₃・ ・ ・ Aj ・ ・ ・ calculated based on the formula (generally the formula) and their interference degree I (i, j),
It is a list of the sums of the interference levels I (i, j) calculated based on the formula at the same wavelength, that is, the recommended values S (i).

Each center wavelength λ ₁ , λ ₂・ ・ ・ λ i ・ ・ ・ Recommended value S
If the target spectrum line M _MIN of the center wavelength λ _MIN corresponding to the smallest recommended value S _MIN among (1), S (2) ... S (i) ... is selected, the target spectrum line M _MIN is selected. Spectral interference by coexisting elements with respect to _MIN is minimized.

Next, the configuration of the emission spectroscopic analyzer will be described based on the block diagram of FIG.

1 is a spectroscopic / photometric unit, 2 is a back data calculation device for calculating the inter-wavelength distance aij and the converted unit concentration bij relating to the spectral interference of each element detected by the spectroscopic / photometric unit 1, 3 is the calculated inter-wavelength distance A database in which aij and converted unit concentration bij are registered in advance, 4 is a microcomputer,
Reference numeral 5 is a keyboard as input setting means, 6 is a display, 7 is a printer, and 8 is a coexisting element detection device.

The back data calculation device 2, the database 3, the microcomputer 4, the keyboard 5, the display 6, and the coexisting element detection device 8 constitute a spectrum line selection support device SS.

Next, the operation will be described.

First, back data is constructed prior to actual emission spectroscopy. That is, one of a plurality of elements A ₁ , A ₂ ... Aj ...
Based on the data detected by the spectroscopic / photometric unit 1 for each of them, in the back data calculation device 2, the reference wavelength distance ±
The inter-wavelength distance aij and the converted unit concentration bij within the range of λ _T are calculated, and the results are registered in the database 3 in a spreadsheet format as shown in FIG. 2 to construct back data.

In Fig. 2, the analytical element is A ₁ and the coexisting element is an element other than A ₁ , but in database 3, in addition to the spreadsheet in Fig. ₂ , a spreadsheet with an analytical element as A ₂ , A spreadsheet in which all the elements to be measured are analyzed elements, such as a spreadsheet in which the analytical element is A ₃ is stored.

For example, the elements to be measured are rare earth elements Sc, Y, La, C
If there are 16 kinds of e, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, one spreadsheet for each element, as shown in Fig. 2, A total of 16 spreadsheets will be stored.

Next, based on the flowchart of FIG. 6, the operation for supporting the determination of which wavelength spectral line should be selected when performing actual emission spectroscopic analysis for an element contained in the sample substance is described. Explain.

First, in step S1, when the analysis element is input to the microcomputer 4 from the keyboard 5, the element symbol of the input analysis element is displayed on the display 6. In the following description, as an example, the elements shown in FIG.
It is assumed that A ₁ is entered as the analysis element.

In step S2, when the expected concentration of the analytical element contained in the sample substance is input from the keyboard 5 to the microcomputer 4, the expected concentration is displayed next to the element symbol of the analytical element on the display 6.

In step S3, first select one coexisting element out of all coexisting elements that are considered to be contained in the sample substance using the keyboard 5
Input to the microcomputer 4. Then, the input symbol of the coexisting element is displayed on the display 6.

The input of the coexisting elements from the keyboard 5 is offline, but when inputting online, the
Input through the photometric unit 1 and the coexisting element detection device 8.

In step S4, the expected concentration (cj) of the coexisting element input in step S3 is input to the microcomputer 4 from the keyboard 5. Then, on the display 6, the expected concentration is displayed next to the element symbol of the coexisting element.

In step S5, it is determined whether or not the input of the coexisting element and its expected concentration is completed. If NO, steps S3, S4
Repeat to enter the remaining coexisting elements and their expected concentrations. Thus, in the case of FIG. 2, coexisting elements A ₂ , A ₃ ... A
j ... and the respective predicted concentrations c ₂ , c ₃ ... cj ... are input.

The display state of the display 6 at this time is shown in FIG.

When the input of all the coexisting elements and their expected concentrations is completed, the interference degree I (i, j) is calculated in step S6, and the recommended value S (i) is calculated in step S7.

In step S6, the degree of interference I (i, j) is calculated by the microcomputer 4 from the memory of the individual coexisting elements A ₂ , A _3.
While reading the expected concentrations c ₂ , c ₃ ... cj ... of j
From the spreadsheet for the analytical element A ₁ in the database 3, the inter-wavelength distance aij and the conversion unit concentration bij for all coexisting elements are read for each wavelength λi (i = 1, 2 ...), and the formula (general The formula is based on the formula). In the case of the formula, since I (i, j) = cj · bij / | aij |, for example, I (1,2) is the interference degree of the coexisting element A ₂ with respect to λ ₁ , and I (1,2) = c ₂ · b ₁₂ / | a ₁₂ |

As a result of the above calculation, the degree of disturbance I as shown in FIG.
The data of (i, j) is obtained.

Further, the calculation of the recommended value S (i) in step S7 is performed based on the formula from the data of the degree of interference I (i, j) shown in FIG. For example, in the case of the recommended value S (1) for the wavelength λ ₁ , Becomes

That is, in FIG. 4, the interference levels are summed in the vertical direction for each wavelength λi. As a result, the recommended values S (1), S (2) ... S (i) ... Shown at the bottom of FIG. 4 are obtained.

In case of recommended values in step S8 S (1), S (2) ... S
(I) are sorted in ascending order (arranged from the smallest value to the largest value) to determine the order of the recommended value S (i).

In step S9, each recommended value S (i) and the corresponding wavelength λi are displayed on the display 6 according to the recommended value order as shown in FIG. In the display example of FIG. 8, S (5) <S (8)
<S (1) <S (7) <S (6) <S (3) <S (2)
This is the case of <S (4).

In step S10, the analyst looks at the list on the display 6 and determines the wavelength λ _MIN = S _MIN = S _MIN = S (5)
λ ₅ is selected and input from the keyboard 5 to the microcomputer 4.

As a result, the target spectral line M of the wavelength λ _MIN that does not cause the spectral interference or has the least effect even if it occurs.
Assistance in selecting the _MIN is provided, and the selection can be made easy and accurate.

In step S11, a rank No. corresponding to the desired recommended value S (i) can be designated and the wavelength-intensity characteristic curve can be displayed on the display 6. When the rank No. 1 corresponding to the smallest recommended value S (5) is designated, for example, as shown in FIG. 9, only the target spectral line M ₅ of the wavelength λ ₅ of the analytical element A ₁ is displayed, or Although not shown, the spectrum lines of the analysis element and the spectrum lines of the coexisting element having a sufficiently long wavelength distance or the coexistence element having a sufficiently low intensity are displayed.

Further, for reference, when the rank No. 6 corresponding to the large recommended value S (3) is designated, for example, as shown in FIG. 10, the target spectral line M ₆ of the wavelength λ ₆ of the analysis element A ₁ is obtained. , A plurality of disturbing spectral lines N ₆ j, N ₆ , j _{+ 1} , N ₆ , j ₊₂ are displayed.

In step S12, the necessary data is printed out by the printer 7.

As described above, the wavelength λ that does not cause spectral interference
After selecting the spectral lines M _MIN of _MIN, is the emission spectroscopy analysis element for the sample material is carried out.

The present invention also includes the following configurations as examples.

(I) In the above embodiment, the recommended value set S is obtained in step S8.
For (1), S (2) ... S (i) ..., they were sorted in ascending order and the ranking of the recommended value S (i) was determined.
The minimum recommended value S _MIN may appear at multiple wavelengths. That is, when the three recommended values are the same in the above recommended value order (S (5) = S (8) = S (1) <S (7) <
It may be difficult to decide which of S (6) ..., S (5), S (8) and S (1) should be selected.

In order to eliminate this, the BEC value βi is added to the sorting of the recommended value rank.

That is, S (5) = S (8) = S (1) <S (7) <
If S (6) <S (3) <S (2) <S (4), then S
BEC values corresponding to (5), S (8), S (1) β ₅ , β ₈ , β ₁
Are sorted in ascending order, and if β ₈ <β ₁ <β ₅ , then the smaller BEC value is given priority, and as shown in FIG. 11, S (8) → S (1) → S (5) → S (7) → S
It is displayed on the display 6 in the order of (6) → S (3) → S (2) → S (4).

(II) Same aim as above (I), but recommended value S (i)
After sorting (i = 1, 2 ...), the BEC values βi are not sorted when the same recommended value exists, but the recommended value S (i) and the BEC value βi are not sorted for each wavelength λi. The product S (i) × βi (i = 1,2 ...) Is calculated and the product S
(I) × βi itself is sorted in ascending order.

G. Effects of the Invention According to this invention, the following effects are exhibited.

That is, the recommended values, which are the sum of the interference levels for each wavelength of each item spectral line, are sorted in order of size, and the recommended values are displayed according to the sorting order, so that the wavelength at which the analyst does not cause spectral interference or is the most unlikely to occur. It can provide very effective assistance in easily and accurately selecting the target spectral line of.

[Brief description of drawings]

1 to 10 relate to an embodiment of the present invention.
The figure shows the inter-wavelength distance, Fig. 2 shows the spreadsheet of back data, Fig. 3 shows the BEC value, Fig. 4 shows the format of interference degree and recommended value, and Fig. 5 shows the emission spectrum analysis. Block diagram of the device, FIG. 6 is a flow chart for explaining the operation, FIG. 7 is a display display diagram when inputting analytical elements and coexisting elements, FIG. 8 is a display diagram of recommended values, and FIGS. 9 and 10 are It is a display figure of a wavelength-intensity characteristic curve. FIG. 11 is a display diagram of recommended values according to another embodiment.
Further, FIG. 12 is an explanatory diagram of spectral interference. Mi …… Target spectral line Nij …… Interference spectral line aij …… Distance between wavelengths bij …… Converted unit concentration cj …… Actual concentration I (i, j) …… Interference degree S (i) …… Recommended value SS …… Spectral line selection support device 3 ... Database 4 ... Microcomputer (calculation means) 5 ... Keyboard (input means) 6 ... Display (display means)

Claims (1)

[Claims] 1. A wavelength-to-wavelength distance between interference spectrum lines of a plurality of coexisting elements capable of causing spectral interference with respect to each of the plurality of target spectrum lines of each element to be measured and a unit concentration of the coexisting element. Database for registering back data of intensity (converted unit concentration) of interference spectrum line per hit, means for inputting actual concentration of coexisting element, and each target spectral line based on the wavelength distance, converted unit concentration and actual concentration The interference degree, which is the degree of spectral interference received by, is calculated, and the recommended value, which is the sum of the interference degrees by the individual coexisting elements, is calculated for the wavelength of each target spectral line, and these recommended values are sorted in ascending order of size. An emission spectroscopic analysis method provided with a calculation means and a display means for displaying the recommended values and the wavelengths corresponding to the recommended values according to the order of the sorting. Vector line selection support device.