Automatic baseline correction method for infrared spectroscopy

An infrared spectrum and baseline correction technology, applied in the field of infrared spectrum analysis, can solve the problems of reducing the universality and adaptability of the baseline correction method, poor performance, and difficulty in meeting the needs of infrared spectroscopy

Active Publication Date: 2017-12-01
HEFEI INSTITUTES OF PHYSICAL SCIENCE - CHINESE ACAD OF SCI
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  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The so-called baseline correction is to artificially pull the baseline of the infrared spectrum back to the 0 baseline, but most of the baseline correction methods now need to set some empirical parameters, which reduces the universality and accuracy of the baseline correction method to a certain extent. Adaptability, it is difficult to meet the needs of real-time online analysis of infrared spectroscopy
For example, the polynomial fitting algorithm assumes that the baseline can be approximated as a low-order polynomial, fits the data with a suitable polynomial, discards any points on the fitted curve that are greater than a certain standard deviation, and repeats this step for the remaining points , until no data points need to be discarded, and this method performs poorly in the case of low signal-to-noise ratio or low signal-to-background ratio; the baseline correction of the automatic iterative moving average method is not smooth enough in the case of multiple peaks or overlapping peaks and the effect Not very good; both the ALS method and the airPLS method are based on Whittaker smooth baseline correction, and the baseline correction effect is better, but both require parameter optimization, and adjusting the optimal parameters is a process that requires experience; the traditional Rubber-band method will The spectrum is divided into several parts, the lowest point of each part is considered as the position of the baseline, and then the estimated baseline is completed by combining these points with linear interpolation or spline interpolation. This method needs to manually adjust the segment width and correct the results. Depends to some extent on the experience of the operator

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  • Automatic baseline correction method for infrared spectroscopy
  • Automatic baseline correction method for infrared spectroscopy
  • Automatic baseline correction method for infrared spectroscopy

Examples

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specific Embodiment 1

[0023] (1) Gather an absorption spectrogram containing 115ppm standard SF6 gas component with the self-developed open Fourier transform infrared spectrometer, and obtain a certain band range of SF6 absorbance spectrum through preprocessing, where the spectral band is 917cm -1 ~962cm -1 band;

[0024] (2) Concretely adopt an open Fourier transform infrared spectrometer, determine the iteration threshold λ for SF6 gas components to be 0.007, then use the method of the present invention to process the SF6 absorbance spectrum of this band, obtain the processed SF6 absorbance The baseline of the spectrum, such as figure 2 shown;

[0025] (3) Then use other baseline correction methods to process the SF6 absorbance spectrum to obtain the corrected spectrum baseline for comparison. The present invention performs iterative calculation by setting the iterative threshold λ, and constantly pulls the absorbance spectrum back to the baseline 0 , to complete the correction of the origina...

specific Embodiment 2

[0026] (1) Use the self-developed open Fourier transform infrared spectrometer to collect an absorption spectrum containing 115ppm standard SF6 gas components, and obtain the SF6 transmittance spectrum in a certain band range through preprocessing, where the spectral band is 917cm -1 ~962cm -1 band;

[0027] (2) Concretely adopt an open Fourier transform infrared spectrometer, determine the iteration threshold λ for SF6 gas components to be 0.007, then use method two of the present invention to process the SF6 transmittance spectrum of this band, obtain the processed The baseline of SF6 transmittance spectrum, such as Figure 5 shown;

[0028] (3) Then use other baseline correction methods to process the SF6 transmittance spectrum to obtain the corrected spectral baseline for comparison. The present invention performs iterative calculation by setting the iterative threshold λ, and constantly pulls the transmittance spectrum back To the baseline 1, the calibration of the ori...

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Abstract

The invention discloses an automatic baseline correction method for infrared spectroscopy. The automatic baseline correction method comprises the following steps: A1, preparing a to-be-detected sample; B1, acquiring an infrared spectrum of the to-be-detected sample by using a spectrograph, and preprocessing the spectrum to obtain the original absorbance spectrum; C1, for spectral intensity Y=[y1, y2...yN] in the original absorbance spectrum at equal interval, performing average minimum updating on the original absorbance spectrum, and obtaining the spectral intensity Y1=[y1,...yi+1] of the absorbance spectrum after the first update; D1, calculating the sum of range differences, namely Sabs(1) =Sigma of an absolute value of (Y-Y1); E1, repeating the step C1 for performing iterative computations for n times, updating the Y1 to obtain Y2, deducing the rest to obtain the Y1, Y2...Yn, further performing iterative computations on the step D1 to obtain Sabs(n), then calculating until the deltaSabs(n-1)/Sabs(n) is less than or equal to an iterative threshold lambda, and stopping calculating to obtain a baseline Yn of the absorbance spectrum, wherein n is more than 2; and F1, subtracting the baseline from the original absorbance spectrum, thereby obtaining the corrected absorbance spectrum.

Description

technical field [0001] The invention belongs to the field of infrared spectrum analysis, in particular to an automatic baseline correction method of infrared spectrum. Background technique [0002] Infrared spectral analysis is an important method for qualitative substance. Its analysis can provide a lot of information about functional groups. During the qualitative and quantitative analysis of Fourier transform infrared spectroscopy, baseline correction of the original spectrum is a key step in the spectral processing process. Infrared Changes in the light source of the spectrometer, the state of the instrument, and the atmospheric environment will cause a certain baseline drift in the measured infrared spectrum. In order to achieve real-time processing and analysis of the spectrum, it is first necessary to perform automatic baseline correction on the spectrum. The so-called baseline correction is to artificially pull the baseline of the infrared spectrum back to the 0 bas...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N21/35
CPCG01N21/35G01N2021/3595
Inventor 徐亮沈先春叶树彬胡荣金岭徐寒杨刘文清刘建国
Owner HEFEI INSTITUTES OF PHYSICAL SCIENCE - CHINESE ACAD OF SCI
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