CN112730290B - Multi-optical path absorption spectrum spectrogram synthesis method - Google Patents

Abstract

The invention relates to a multi-optical path absorption spectrum spectrogram synthesis method, which comprises the following contents: selecting an optical path group to be detected according to the performance of the multi-optical path absorption spectrum detection equipment; according to the selected optical path group, performing absorption spectrum detection by using multi-optical path absorption spectrum detection equipment, and performing unitization processing on the acquired absorption spectrum; and carrying out spectrum synthesis on the absorption spectra acquired based on different optical paths. The invention provides a complete solution for combining the absorption spectra of the same sample in different optical paths, and the synthesized spectrogram can simultaneously have absorption peaks with larger absorption coefficient difference, thereby improving the fidelity of the spectrum shape.

Description

A method for synthesizing multi-optical path absorption spectra

technical field

The invention relates to a method for synthesizing a multi-optical path absorption spectrum spectrum, and relates to the technical field of spectrum detection.

Background technique

When performing absorbance (or absorption spectrum) detection, the detection result under a single optical path within the optimal absorbance detection range of the instrument will be selected by comparing the absorbance values under multiple optical paths, representing the properties of the sample. For the absorbance detection of a single wavelength, this detection method can obtain the best absorbance detection result of the wavelength, but if the absorbance (absorption spectrum) of multiple wavelengths is involved, this method cannot guarantee the existence of a specific optical path for the absorbance of different wavelengths. detection can be optimal. In the fields of medicine, food, dyes, environment, etc., there is a need for qualitative analysis or chemometric detection of samples by absorption spectroscopy. In this demand, the high-fidelity acquisition of the shape of the absorption spectrum is particularly important. Therefore, a multi-optical path absorption spectrum synthesis method is required, so that in the same absorption spectrum, the absorbance detection data at each wavelength are derived from The best detection range of the instrument.

There are also design methods for variable optical path detection optical paths or hardware in the prior art, but none of them involve a multi-optical path absorption spectrum synthesis method. In addition, due to the interference of over-range distortion, baseline drift, random errors, etc., when the detection equipment performs absorption spectrum detection, when synthesizing absorption spectrum spectra, it is necessary to overcome various detection errors to ensure the high-fidelity performance of the synthesized spectrum.

SUMMARY OF THE INVENTION

In view of the above problems, the purpose of the present invention is to provide a method for synthesizing a multi-optical path absorption spectrum that can ensure the fidelity of the spectral shape.

To achieve the above object, the present invention adopts the following technical solutions: a method for synthesizing a multi-optical path absorption spectrum, comprising the following contents:

Select the optical path group to be measured according to the performance of the multi-optical path absorption spectrum detection equipment;

According to the selected optical path group, the absorption spectrum is detected by the multi-optical path absorption spectrum detection equipment, and the collected absorption spectrum is unitized;

Spectral synthesis is performed on absorption spectra collected based on different optical lengths.

The method for synthesizing the multi-optical path absorption spectrum spectrum, further, selecting the optical path group to be measured according to the performance of the multi-optical path absorption spectrum detection equipment includes:

Determine the optimal absorbance detection interval (a, b) of the multi-optical path absorption spectrum detection equipment;

Take the ratio b/a of the upper limit and lower limit of the optimal absorbance detection interval as the span;

Select several optical paths A1...An between the maximum optical path and the minimum optical path that can be collected by the multi-optical path absorption spectrum detection device, so that the adjacent optical path ratio Ai/Ai+1 is slightly smaller than the span b/a.

In the method for synthesizing the multi-optical path absorption spectrum, further, unitizing the collected absorption spectrum includes:

Adjust the optical path to A1...An and perform absorption spectrum detection respectively, collect the absorption spectrum of each optical path A1...An, and obtain a series of optical path-absorption spectrum diagrams;

Eliminate the optical path that does not overlap the measured absorption spectrum and the optimal absorbance detection range;

Unitize by dividing the effective spectrum by its optical length.

In the method for synthesizing the multi-optical path absorption spectrum, further, unitization is performed according to Beer-Lambert's law, that is, the spectrum in the optimal absorbance detection interval is divided by its optical path to calculate the unit optical path absorption spectrum.

In the method for synthesizing multi-optical path absorption spectra, further, performing spectral synthesis on absorption spectra collected based on different optical paths includes:

Identify the overlap between the optimal ranges of different optical path spectra according to the interval intersection;

The overlapping part of the adjacent optical path is weighted and averaged with the optical path Ai and Ai+1 as the weight, and the average value is obtained as the final spectrum of the overlapping part;

Using the final spectrum of the overlapping part as a reference, calculate the average value of the spectral overlap part of each optical path after averaging;

If there is an extension of the maximum or minimum path length, adjust with the non-overlapping portion of the maximum or minimum path length.

In the method for synthesizing the multi-optical path absorption spectrum, further, for the maximum optical path length and the minimum optical path length, the non-overlapping part can be adjusted by the same amount as the correction value of the overlapping part; the correction parameter of the non-overlapping part of the optical path in the middle The difference value of the parameter is corrected for both ends, so that the overlapping part and the non-overlapping part have better continuity in the complete spectrum.

In the method for synthesizing the multi-optical path absorption spectrum, further, if the error of the overlapping parts of adjacent optical paths deviates from the constant error, linear fitting can be performed on the values before and after the weighted average of the overlapping parts, and the value before the average is taken as the self-value. Variable X, the averaged value is the dependent variable Y, the slope and intercept are obtained by linear fitting, which are used to correct the non-overlapping part; the maximum optical path and the minimum optical path directly apply the linear function obtained by fitting to the non-overlapping part Correction is performed; for the middle optical path, the slope and intercept of the overlapping parts at both ends are differentially calculated to obtain the correction coefficient corresponding to the absorbance of each wavelength.

The present invention has the following advantages due to taking the above technical solutions:

1. The present invention provides a complete solution for merging absorption spectra of different optical paths of the same sample, and absorption peaks with large differences in absorption coefficients can exist simultaneously in the synthesized spectrum, which improves the fidelity of the spectral shape;

2. The present invention provides a criterion and method for selecting an optical path according to the performance of the equipment for the instrument and equipment that can perform variable optical path absorption spectrum detection;

3. The present invention expands the detection range compared with the single-light-path absorption spectrum through the synthesis of multiple optical paths, especially for equipment with a small range under a single optical path but can be adapted to a large optical path range, the effect of extending the range is remarkable;

4. While performing spectrum synthesis, the present invention has the effect of error correction for random errors and baseline drift;

In conclusion, the present invention provides support for the development and automatic application scheme of an automatic variable optical path absorption spectrum detection device, and can be widely used in sample spectrum detection.

Description of drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are for the purpose of illustrating preferred embodiments only and are not to be considered limiting of the invention. The same reference numerals are used to refer to the same parts throughout the drawings. In the attached image:

1 is a flowchart of a method for synthesizing a multi-optical path absorption spectrum according to an embodiment of the present invention;

2 is a schematic diagram of splicing absorption spectra of different optical paths according to an embodiment of the present invention;

FIG. 3 is a spectrogram before and after synthesis according to the embodiment of the present invention, wherein (a) is a spectrogram of each optical path unit before synthesis, and (b) is a spectrogram after synthesis.

Detailed ways

Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present invention will be more thoroughly understood, and will fully convey the scope of the present invention to those skilled in the art.

It is to be understood that the terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms "a," "an," and "the" can also be intended to include the plural forms unless the context clearly dictates otherwise. The terms "comprising", "comprising", "containing" and "having" are inclusive and thus indicate the presence of stated features, steps, operations, elements and/or components, but do not preclude the presence or addition of one or Various other features, steps, operations, elements, components, and/or combinations thereof. Method steps, procedures, and operations described herein are not to be construed as requiring that they be performed in the particular order described or illustrated, unless an order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

For ease of description, spatially relative terms may be used herein to describe the relationship of one element or feature to another element or feature as shown in the figures, such as "inner", "outer", "inner" ", "outside", "below", "above", etc. This spatially relative term is intended to include different orientations of the device in use or operation other than the orientation depicted in the figures.

The invention provides a method for synthesizing a multi-optical path absorption spectrum spectrum. Spectral detection and unitization of the collected absorption spectra; spectral synthesis of absorption spectra collected based on different optical path lengths. The invention provides a complete solution for merging absorption spectra of different optical paths of the same sample, and absorption peaks with large differences in absorption coefficients can exist simultaneously in the synthesized spectrum, thereby improving the fidelity of the spectral shape.

Beer-Lambert's law is the basic rule for combining multi-optical path spectra. Each absorbance is proportional to the optical path. The synthesis method of multi-path absorption spectra needs to be based on Beer-Lambert's law. Through process design and algorithm processing, high fidelity can be obtained. Synthetic spectrum of degrees.

As shown in FIG. 1 , the method for synthesizing a multi-optical path absorption spectrum provided by an embodiment of the present invention includes the following contents:

S1. For multi-optical path absorption spectrum detection equipment, select the optical path group to be measured according to the performance of the detection equipment, specifically including:

S11. Determine the optimal absorbance detection range of the multi-optical path absorption spectrum detection device by referring to the description or actual testing.

Specifically, the optimal absorbance detection interval range is obtained or estimated according to the original light intensity, dynamic range, sensitivity, linear range and other parameters of the multi-optical path absorption spectrum detection device as a whole or its main components. Among them, "acquisition" means that the overall specification of the spectral detection equipment has a direct record, and "estimation" is to use the parameters of the components to calculate the overall performance. The above processes are all existing technologies. The estimation of the detection interval, for example, is not limited to this; alternatively, a device with a known absorption spectrum, such as a standard filter, can be used to test the multi-optical path absorption spectrum detection equipment to obtain the optimal suitable for all wavelengths. Absorbance detection interval, define the optimal absorbance detection lower limit as a, upper limit as b, and the optimal interval as (a, b).

S12, taking the ratio b/a of the upper limit to the lower limit of the optimal absorbance detection interval as the span.

S13. Select several optical paths A1...An (from large to small) between the maximum optical path and the minimum optical path that can be collected by the multi-optical path absorption spectrum detection device, so that the adjacent optical path ratio Ai/Ai+1 is slightly smaller than The span is b/a, so as to ensure that the detection spectra of two adjacent optical paths have a partially overlapping optimal detection range, and the specific value can be selected according to actual needs, which is not limited here.

S2. Collect absorption spectra and perform unitization processing, including:

S21. Adjust the optical path to A1...An and perform absorption spectrum detection respectively, collect the absorption spectrum of each optical path A1...An, and obtain a series of optical path-absorption spectrum diagrams.

S22. Eliminate the optical path whose measured absorption spectrum and the optimal absorbance detection range do not overlap completely (only appear at the maximum end or the minimum end of the optical path group A1...An).

S23: Divide the effective spectrum (that is, the spectrum measured under the remaining optical path after the elimination in S22) by its optical path, and perform unitization processing.

Specifically, the unitization process is performed according to Beer-Lambert's law, that is, the absorption spectrum per unit optical path is calculated by dividing the spectrum in the optimal absorbance detection interval by its optical path. After this step, the obtained spectrum is shown in Figure 2 on the absorbance number axis. The larger the optical path length, the smaller the unitized value of the corresponding optimal absorbance detection interval. Since the ratio of two adjacent optical paths is smaller than the span, and the absorption spectrum is a continuous curve, the absorption spectrum obtained by any two adjacent optical paths has an overlap of 2-7 of the interval intersection of the optimal range, that is, The intersection of the optimal detection interval of two adjacent optical paths, in this wavelength interval, the spectra measured by the adjacent optical paths have high reliability.

S3. Since the optical path is used as the denominator during unitization, the random errors and baseline drift that are not related to the optical path in the device detection are scaled. Therefore, the larger the optical path, the smaller the introduction of this type of error. Based on this The specific process of spectral synthesis includes:

S31. Identify 2-7 overlapping parts between optimal ranges of different optical path spectra according to the interval intersection.

S32. Perform a weighted average on the overlapping parts of the adjacent optical paths with the optical paths Ai and Ai+1 as the weights to obtain the average value as the final spectrum of the overlapping part, and the overlapping part only includes the wavelength intersection corresponding to the interval of the two adjacent optical paths , the final spectrum of this part of the wavelength is obtained by means of weighted average. Since the optical path is used as the weight to perform the weighted average, the absorption spectrum detected under the large optical path has an influence on the final spectrum of the overlapping part, so that the final spectrum is greatly affected by the detection result of the large optical path.

S33 , using the final spectrum of the overlapping portion as a reference, calculate the average value of the spectral overlap portion of each optical path corrected after averaging.

For the maximum optical path length and the minimum optical path length, the non-overlapping part can be adjusted by the same amount as the correction value of the overlapping part;

The correction parameter of the non-overlapping part of the optical path in the middle is the difference value of the correction parameters at both ends, so that the overlapping part and the non-overlapping part have better continuity in the complete spectrum. In this process, the mean correction of the constant baseline drift that occurs in the detection of different optical lengths is achieved at the same time.

Further, if the error of the overlapping part of the adjacent optical paths deviates from the constant error (the overlapping part is a wavelength interval, which contains the absorbance values of multiple wavelengths, if within this interval, the deviation between the final spectrum and the spectrum of a certain optical path is basically Consistent, then it is a constant error, if the deviation from left to right in the interval gradually increases or decreases, it is a non-constant error), and the values before and after the weighted average of the overlapping parts can be linearly fitted. Taking the value before averaging as the independent variable X, and the value after averaging as the dependent variable Y, the slope and intercept are obtained by linear fitting, which are used for the non-overlapping part (the final spectrum of the overlapping part is weighted average, and the other parts are The value is corrected to connect to the overlapped part). The maximum optical path length and the minimum optical path directly apply the linear function obtained by fitting to correct the non-overlapping part; for the middle optical path, the slope and intercept of the overlapping parts at both ends are differentially calculated to obtain the correction coefficient corresponding to the absorbance of each wavelength. This method can average the possible linear drift of the device detection baseline.

S34. If there is an extension of the maximum optical path or the minimum optical path (the absorbance is less than the optimal range of the maximum optical path or greater than the optimal range of the minimum optical path, these parts are not in the optimal range of any optical path), the maximum Optical path extension ranges 2-1 and 2-6 The minimum optical path extension range is adjusted with the non-overlapping portion of the maximum or minimum optical path.

The application of the method for synthesizing the multi-optical path absorption spectrum provided by the present invention will be described in detail below through specific embodiments.

The method for synthesizing a multi-optical path absorption spectrum spectrum in this embodiment is applied to the variable optical path spectrum synthesis of an absorption spectrum detection device, and this embodiment uses a COD standard solution potassium hydrogen phthalate as a detection reagent.

According to step S1, the light intensity dynamic range test is performed on the absorption spectrum detection device. The optimal absorbance detection range at the minimum detection wavelength is (0.07, 0.82), and the optimal absorbance range of other wavelengths covers this range, so it is determined The optimal range of absorbance of the device is (0.07, 0.82), and its span is calculated to be 11.7, so 10 can be selected as the ratio of two adjacent optical paths. Within the adjustable optical path range of the device, 3 optical path values A1, A2 and A3 can be taken as 100mm, 10mm and 1mm respectively.

According to step S2, the absorption spectra under the three optical paths are detected respectively.

For convenience of presentation, 200nm to 300nm are recorded at 5mm intervals as shown in Table 1, and the absorption spectra of each optical path have detection values within the optimal range. The unit optical path (in m) spectrum obtained by dividing each spectrum by its optical path is shown in Figure 3, and the optimal detection range of each spectrum is marked with hatching in Table 1 according to Figure 2.

Table 1 Original spectrum, normalized spectrum and composite spectrum of different optical paths

According to step S3, the spectrum at 100mm optical path is first combined with the spectrum at 10mm.

Perform a weighted average of the overlapping optimal absorbance ranges of the two optical paths near 255 nm. According to step S32, the weight of the 100 mm optical path is 100, and the weight of the 10 mm optical path is 10, and the synthesized final spectrum of this region can be obtained, at 255 nm. The absorbance after synthesis was 6.28, ie (6.10*100+8.14*10)/11. According to step S33, the value after unitization of the 100mm optical path must be increased by 0.18, that is, 6.28-6.10=0.18, and the value of the spectrum after the unitization of the 10mm optical path must be decreased by 1.86, that is, 6.28-8.14=-1.86. For the merging of the 10mm spectrum and the 1mm spectrum, step S32 is also used to perform the weighted average of the overlapping areas of 2-7, and the final absorbances at 210, 215, and 220 nm are 87.70, 55.18, and 40.68, respectively. The difference between the final spectral overlap and the 1mm spectrum 188.32-87.70=100.62, 107.84-55.18=52.66, 71.83-40.68=31.15 is not a constant, but is related to the size of the absorbance, and there is a significant unidirectional decreasing trend, so this segment is found There may be a linear baseline error, so a linear fit is performed according to the preferred method. The linear correction function of the mean value of the overlapping portion is Y=1.17X-3.28 for the 10mm spectrum and Y=0.41X+11.35 for the 1mm spectrum.

For the spectral value with the maximum optical path length of 100mm, it can be used as the final spectrum by increasing 0.18 (Y=X+0.18). For a spectrum with an optical path of 10mm, a differential correction of Y=X-1.86 at one end and Y=1.17X-3.28 at the other end is required (the correction for the overlapping part of the 10mm optical path and the 100mm optical path is Y=X-1.86, and the 10mm optical path is Y=X-1.86. The correction for the overlapping part with the 1mm optical path is Y=1.17X-3.28), for example, in the 10mm optical path spectrum, the absorbance in the range from 225nm to 250nm needs to be adjusted, then for the absorbance at 245nm, the slope of the adjustment is the slope of the two ends The 5th point between 1 and 1.17 is 1.034 or (1.17-1)/5+1, and the intercept is the 5th point between -1.86 and -3.28 -2.144 which is (-3.28-(-1.86))/ 5+(-1/86), the spectrum after synthesis is shown in the last column of Table 1, and the unitized spectrum before and after synthesis is shown in Figure 3.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that it can still be Modifications are made to the technical solutions described in the foregoing embodiments, or some technical features thereof are equivalently replaced, and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (6)

1. a multi-optical path absorption spectrum spectrogram synthesis method is characterized in that comprising the following content: Select the optical path group to be measured according to the performance of the multi-optical path absorption spectrum detection equipment; According to the selected optical path group, the absorption spectrum is detected by the multi-optical path absorption spectrum detection equipment, and the collected absorption spectrum is unitized; Spectral synthesis is performed on absorption spectra collected based on different optical path lengths. The process includes: Identify the overlap between the optimal ranges of different optical path spectra according to the interval intersection; The overlapping part of the adjacent optical path is weighted and averaged with the optical path Ai and Ai+1 as the weight, and the average value is obtained as the final spectrum of the overlapping part; Using the final spectrum of the overlapping part as a reference, calculate the average value of the spectral overlap part of each optical path after averaging; If there is an extension of the maximum or minimum path length, adjust with the non-overlapping portion of the maximum or minimum path length. 2. The method for synthesizing a multi-optical path absorption spectrum spectrum according to claim 1, wherein the selected optical path group to be measured according to the performance of the multi-optical path absorption spectrum detection equipment comprises: Determine the optimal absorbance detection interval (a, b) of the multi-optical path absorption spectrum detection equipment; Take the ratio b/a of the upper limit and lower limit of the optimal absorbance detection interval as the span; Select several optical paths A1...An between the maximum optical path and the minimum optical path that can be collected by the multi-optical path absorption spectrum detection device, so that the adjacent optical path ratio Ai/Ai+1 is slightly smaller than the span b/a. 3. The method for synthesizing a multi-optical path absorption spectrum spectrum according to claim 2, characterized in that, unitizing the collected absorption spectrum comprises: Adjust the optical path to A1...An and perform absorption spectrum detection respectively, collect the absorption spectrum of each optical path A1...An, and obtain a series of optical path-absorption spectrum diagrams; Eliminate the optical path that does not overlap the measured absorption spectrum and the optimal absorbance detection range; Unitize by dividing the effective spectrum by its optical length. 4. multi-optical path absorption spectrum spectrogram synthesis method according to claim 3, is characterized in that, carry out unitization process according to Beer-Lambert's law, namely divide the spectrum of optimum absorbance detection interval by its optical path to calculate unit light absorption spectrum. 5. multi-optical path absorption spectrum spectrum synthesis method according to claim 1, is characterized in that, for maximum optical path and minimum optical path, can adjust non-overlapping part with the correction value of overlapping part equal amount; The correction parameter of the non-overlapping part of the process is the difference value of the correction parameters at both ends, so that the overlapping part and the non-overlapping part have better continuity in the complete spectrum. 6. multi-optical path absorption spectrum spectrogram synthesis method according to claim 1, is characterized in that, if the error of adjacent optical path overlapping part deviates from constant error, can carry out linear fitting to the numerical value before and after the weighted average of overlapping part, Taking the value before averaging as the independent variable X, and the value after averaging as the dependent variable Y, the slope and intercept are obtained by linear fitting, which are used to correct the non-overlapping part; the maximum optical path and the minimum optical path are directly obtained by fitting The non-overlapping part is corrected by the linear function of ; in the middle optical path, the slope and intercept of the overlapping parts at both ends are differentially calculated to obtain the correction coefficient corresponding to the absorbance of each wavelength.

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