JPH06160188A - Method for determining peak position of original spectrum - Google Patents

Abstract

PURPOSE:To efficiently detect many positions of acute and high peaks at once by differentiating original spectrums in the even order, and obtaining the mixed spectrums from the differentiated spectrums thus obtained and the original spectrums. CONSTITUTION:Original spectrums are secondarily differentiated, and the differentiated spectrums Q1-Q10 thus obtained correspond to the original spectrums P1-P10. The peak P5 is the highest and the peak P6 is the lowest in the original spectrums P1-P10. When the original spectrums are differentiated twice, peaks Q6, Q8, Q9 in Q1-Q10 have considerably large amplitudes. For the mixing of the original spectrums and the differentiated spectrums, corresponding points may be added or multiplied. When the original spectrums and the differentiated spectrums are mixed, positions of high and acute peaks can be preferentially detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for obtaining a large number of peak positions at one time in a spectrum obtained by an absorption method, a light emission method, a fluorescence method or the like.

[0002]

2. Description of the Related Art Conventionally, for searching a peak in a spectrum, for example, when the direction of the peak is in the upper direction of the vertical axis as shown in FIG. 3A, digitized (discretized) data is used. From the set that is convex upwards in the column, the data in the central part is ordered from the largest (for example, the order of)
Until the threshold value SL determined in step 1 is reached, or a predetermined number is reached, selection is made.

[0003]

By the way, in the above-mentioned method, as shown in FIG. 3A, it is required that the baseline BL in the spectrum is flat and that there is no broad peak. It is difficult to obtain such an ideal spectrum. For example, the figure (B)
As shown in, when the baseline BL fluctuates, a portion that should not be originally searched is searched for as a peak. Further, as shown in (C) of the figure, if there is a broad absorption band AZ, it is not the original search target,
Since the peak is high, it is erroneously detected as the peak position. Therefore, in such a case, the target area SZ of the peak search is designated as shown in FIG.

As described above, in the prior art, since the extra searched peaks are erased and re-searched or the search target area is limited, it takes time and labor to find a desired peak. there were.

The present invention has been made in view of the above matters, and an object thereof is to provide a method capable of efficiently detecting a large number of sharp and high (deep) peak positions in a spectrum. Especially.

[0006]

In order to achieve the above object, a method for obtaining a peak position of a spectral spectrum according to the present invention performs even-order differentiation of the spectral spectrum, and obtains the obtained differential spectrum and the spectral spectrum. , The corresponding points are added or multiplied to obtain the mixed spectrum, and the peak position is determined based on the mixed spectrum.

[0007]

The function of the absorption band (emission band) for which the measurer of the spectrum wants to know the peak position is usually sharp and high (deep). In the second derivative spectrum obtained by the second derivative of the spectral spectrum, the sharper the absorption band (emission band) is, the larger the shake is, which is an index representing the sharpness. Therefore, even if the baseline of the original spectrum is not flat, it becomes flat in the second derivative spectrum, and the broad absorption band also has a smaller fluctuation than the focused absorption band. By adding or multiplying such a second derivative spectrum to the original spectrum and mixing them, it is possible to efficiently detect many sharp and high (deep) peak positions in the spectrum at one time.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1A shows an example of an infrared absorption spectrum (abscissa on the vertical axis and wave number on the abscissa). In this figure, symbols P _{1 to} P ₁₀ indicate positions where peaks are to be detected. Then, in this spectrum, the baseline BL is raised at the left end, and there is a broad and high absorption band AZ between the peaks P ₂ and P ₃ .

FIG. 1 (B) is a differential spectrum obtained by second-order differentiation of the spectrum shown in FIG. 1 (A) (hereinafter referred to as the original spectrum), and the symbols Q _{1 to} Q ₁₀ in the figure. ,
It corresponds to the symbols P _{1 to} P ₁₀ in the original spectrum. In this derivative spectrum, there is no rise of the baseline BL as seen in the original spectrum, and a broad absorption band hardly appears in peaks Q ₂ and Q ₃ .

Then, P _{1 to} P in the original spectrum
Among ₁₀ peaks P ₅ are the largest (highest) and peaks P ₆ are the smallest (lowest). On the other hand, when differentiation is performed twice, there is a characteristic that the sharper the peak is, the larger the fluctuation is. Therefore, among Q _{1 to} Q ₁₀ in the differential spectrum, the peak Q ₆ has a considerably large fluctuation. . Similarly, the peaks Q ₈ and Q ₉ also have considerably large fluctuations.

Here, it is conceivable that the peak positions in the original spectrum are set in the order of deeper (larger shake) based on only the differential spectrum. In this way, even if there are small peaks in the original spectrum. If it is sharp (for example, the peak P ₆ ), the derivative spectrum will be greatly shaken by differentiating twice, so that it is detected preferentially.

Therefore, the present inventor came up with the idea of appropriately mixing the original spectrum and the derivative spectrum, and when this was done, the peak could be detected in consideration of the height (depth), It was possible to avoid the irrationality described above.

The mixture of the original spectrum and the derivative spectrum may be either addition or multiplication of corresponding points. In this case, both spectra may be appropriately weighted. Hereinafter, a method of mixing both spectra will be described.

First, the method of mixing by adding the original spectrum and the derivative spectrum

When the two spectra are added, the scales of the vertical axes of the two spectra are different from each other.
It is necessary to normalize each data between 0 and 1. Now, the normalized spectra are {a '},
Assuming that {b ′}, the mixed spectrum {c ′} obtained when the two spectra are mixed by addition is represented by the following expression (1). {C ′} = X · {a ′} + Y · {b ′} (1) where X and Y are weighting coefficients, and X, Y ≧ 0, X +
Y = constant.

In the mixed spectrum {c '} obtained as described above, peak positions are preferentially detected in descending order (higher). When both spectra are mixed by this addition, as shown in FIGS. 1 (A) and 1 (B), the shake directions may be opposite between the two spectra. It is preferable to multiply by -1 in advance.

Further, the coefficients X and Y in the above equation (1)
Can be set depending on whether the measurer prefers to detect peak height or sharpness. As the coefficient X becomes larger than the coefficient Y, the problem that the flatness of the baseline BL and the broad absorption band AZ are detected is more likely to occur.

Next, regarding the method of mixing by adding the original spectrum and the derivative spectrum

When the mixed spectrum is obtained by multiplying the original spectrum and the derivative spectrum, it is not necessary to normalize the respective data, unlike the above-mentioned addition. Also in the case of this multiplication, it is preferable to multiply the differential spectrum by -1 in advance when the shake direction is opposite. A mixed spectrum {c} obtained when the two spectra are mixed by multiplication is represented by the following expression (2). {C} = {a + | X |} · {b + | Y |} (2)

Then, in the equation (2), | X | <
If | Y |, the height is given priority, and | X |> | Y
If |, peaks can be detected with priority on sharpness.

FIG. 2 shows the mixed spectrum obtained by the multiplication, and the symbols R _{1 to} R ₁₀ in the figure are the same as those in FIG.
Codes P _{1 to} P in the original spectrum shown in (A)
₁₀ corresponds to symbols Q _{1 to} Q ₁₀ in the differential spectrum shown in FIG. In this example, the coefficients | X | and | Y | are both set to zero.

When the original spectrum shown in FIG. 1 (A) and the mixed spectrum shown in FIG. 2 are compared, the following can be understood.

That is, in the original spectrum, the order of height is P ₅ > P ₁ > P ₈ > P ₄ > P ₂ > P ₉ > P ₃
> P ₇ > P ₁₀ > P _6, and the order of sharpness is
P ₈ > P ₉ > P ₆ > P ₄ > P ₁ > P ₅ > P ₇ > P ₃ > P
And has a _2> P _10. On the other hand, in the mixed spectrum, R ₈ > R ₉ > R ₁ > R ₅ > R ₄ > R ₆ > R
₃ > R ₂ > R ₇ > R ₁₀ .

Therefore, by mixing the original spectrum and the differential spectrum, it is possible to preferentially detect a high and sharp peak (absorption band characteristic of the spectrum), and further, to detect the baseline BL. It can be seen that erroneous detection due to fluctuations and interference due to a broad absorption band is significantly reduced.

Although the original spectrum is second-order differentiated in the above-described embodiment, the present invention is not limited to this, and the original spectrum is even-order differentiated such as fourth-order and sixth-order. Also has the same effect.

[0027]

As described above, according to the present invention,
Many sharp and high (deep) peak positions in the spectrum can be detected efficiently at one time.

[Brief description of drawings]

FIG. 1A is a diagram showing an example of an infrared absorption spectrum, and FIG. 1B is a diagram showing a differential spectrum obtained by second-order differentiating the spectrum shown in FIG.

FIG. 2 is a diagram showing a mixed spectrum obtained by multiplying the spectra shown in FIGS. 1A and 1B respectively.

FIG. 3 is a diagram for explaining a drawback of the conventional method.

[Explanation of symbols]

P _{1 to} P ₁₀ ... Peak position.

Claims (2)

[Claims] 1. Obtaining a plurality of peaks in the spectral spectrum from the largest data to a predetermined threshold value, or a plurality of peaks from the largest data to a predetermined number. In the method for obtaining the peak position of the spectrum spectrum, the even-order differentiation of the spectrum spectrum is performed, and the obtained differential spectrum and the spectrum spectrum are obtained by adding or multiplying corresponding points to obtain a mixed spectrum, A method for obtaining a peak position of a spectral spectrum, characterized in that the peak position is determined based on a mixed spectrum. 2. The method for obtaining the peak position of the spectral spectrum according to claim 1, wherein the spectral spectrum and the differential spectrum are appropriately weighted when the mixed spectrum is obtained.