Method for detecting multiple components in water based on ultraviolet-visible spectrophotometer

Abstract

This invention relates to the field of water quality component detection technology, specifically to a method for detecting multiple water components based on a UV-Vis spectrophotometer. The method includes: acquiring the left and right spectral curves of a dominant absorption peak; analyzing the proximity and smoothness of the wavelengths of the dominant absorption peaks to obtain the preferred side spectral curve for each peak; selecting pure absorption peaks based on the asymmetry of each peak and the difference between its non-preferred side spectral curve and the constructed standard spectral curve; obtaining the difference spectrum between the spectral curve and the standard spectral curve of the pure absorption peak, and repeating this process to obtain all pure absorption peaks; and performing qualitative and quantitative analysis based on the standard spectral curve to obtain the concentration of each component. This invention aims to solve the problem of overlapping absorption peaks of multiple components in the spectral images acquired by a UV-Vis spectrophotometer, thereby improving the accuracy of water quality component detection.

Description

Technical Field

[0001] This invention relates to the field of water quality component detection technology, specifically to a method for detecting multiple water components based on an ultraviolet-visible spectrophotometer. Background Technology

[0002] The UV-Vis spectrophotometer for multi-component water quality detection is based on the fact that when composite light passes through a water sample, each component in the water produces absorbance at a characteristic wavelength according to its concentration and characteristics, based on the Lambert-Beer law (i.e., absorbance is proportional to concentration). The instrument obtains a superimposed mixed absorbance spectrum by scanning multiple wavelengths, and then compares it with a pre-established standard spectral library. The spectral library stores the standard absorbance of each individual component at different wavelengths and its relationship curve with concentration. By comparing the absorbance and concentration of each individual component with those in the water to be tested, the concentration of each component in the water to be tested can be obtained.

[0003] When various components are mixed in the water to be tested, the absorption peaks of these components overlap significantly during the full-spectrum scan because each substance has its own specific absorption spectrum. This results in the composite spectrum curve actually measured by the UV-Vis spectrophotometer being a linear superposition of multiple single spectra. This causes the characteristic absorption peaks that were originally clear and independent in the standard spectral library to be masked or distorted by the absorption of neighboring components, manifesting as peak position shift, peak broadening, or the appearance of shoulder peaks in the measured absorption peaks. When an algorithm is used to match this complex mixed spectrum with a standard library storing curves of single pure components, the deconvolution process cannot accurately separate the superimposed signals that interfere with each other, resulting in fitting errors. This leads to confusion in the qualitative identification of the target components or inaccurate concentration allocation during quantitative calculations, ultimately introducing systematic errors in the detection of multiple components in water quality. Summary of the Invention

[0004] This invention provides a method for detecting multiple components of water quality based on a UV-Vis spectrophotometer to solve existing problems.

[0005] The water quality multi-component detection method based on ultraviolet-visible spectrophotometer of the present invention adopts the following technical solution: One embodiment of the present invention provides a method for detecting multiple components of water quality based on a UV-Vis spectrophotometer, the method comprising the following steps: The spectral curve of the solution to be tested was obtained using a UV-Vis spectrophotometer, and all the main convex absorption peaks and their absorption curves in the spectral curve were obtained. The absorption curves of each convex absorption peak are divided according to its wavelength, resulting in a left and right spectral curve for each peak. The approximation of the left spectral curve to the wavelength of each peak and its smoothness in the rising direction are analyzed to obtain the shape ideality coefficient of the left spectral curve for each peak. The shape ideality coefficient of the right spectral curve is also obtained. The left and right spectral curves are then selected using the shape ideality coefficients to obtain the preferred spectral curve for each peak. A standard spectral curve for each convex absorption peak is constructed based on the preferred side spectral curve; the purity priority of each convex absorption peak is obtained based on the asymmetry of each convex absorption peak and the difference between its non-preferred side spectral curve and the standard spectral curve; the convex absorption peaks are screened using the purity priority to obtain pure absorption peaks. Obtain the difference spectrum between the spectral curve of the test solution and the standard spectral curve of all pure absorption peaks, and record it as the first residual curve of the test solution. Use the first residual curve of the test solution as the new spectral curve, and obtain the new pure absorption peak and the second residual curve. Continue in this way until there exists a constant N such that there is no main convex absorption peak in the Nth residual curve, and obtain the standard spectral curve of all pure absorption peaks. The UV-Vis spectrophotometer performs qualitative and quantitative analysis based on the standard spectral curves of all pure absorption peaks to obtain the concentration of all components in the test solution.

[0006] Preferably, the specific method for obtaining all main convex absorption peaks and their absorption curves in the spectral curve is as follows: The ultraviolet-visible spectrophotometer acquires all the maxima and minima of the spectral curve and marks them as absorption peaks, thus obtaining several main convex absorption peaks of the spectral curve. The spectral curve between the two minimum wavelengths on either side of each dominant absorption peak is denoted as the absorption curve of each dominant absorption peak.

[0007] Preferably, the method for dividing the absorption curve by the wavelength of each main convex absorption peak to obtain the left and right spectral curves of each main convex absorption peak includes the following specific methods: For the i-th dominant convex absorption peak, a standard coordinate system for the i-th dominant convex absorption peak is constructed with the first wavelength of the absorption curve of the i-th dominant convex absorption peak as the origin, the horizontal axis as the wavelength, and the vertical axis as the absorbance. The curve is segmented from the leftmost wavelength of the absorption curve of the i-th convex absorption peak to the wavelength including the i-th convex absorption peak, and then projected onto the standard coordinate system of the i-th convex absorption peak to obtain the left spectral curve of the i-th convex absorption peak. The absorption curve of the i-th convex absorption peak is segmented into sections from the wavelength following the convex absorption peak to the rightmost wavelength. After coordinate reversal, these segments are projected onto the standard coordinate system of the i-th convex absorption peak to obtain the right spectral curve of the i-th convex absorption peak.

[0008] Preferably, the method for analyzing the approximation of the left spectral curve to the wavelength of each main convex absorption peak and its smoothness in the ascending direction to obtain the shape ideality coefficient of the left spectral curve for each main convex absorption peak includes: After calculating the absorbance-wavelength integral of the left spectral curve at the wavelength of the i-th convex absorption peak, the maximum and minimum values ​​of the absorbance-wavelength integral of the left spectral curve at the wavelength of the i-th convex absorption peak are normalized using the integral results of the left spectral curves of all convex absorption peaks, thus obtaining the half-peak area of ​​the left spectral curve at the wavelength of the i-th convex absorption peak. ; Perform a first-order difference calculation on the left spectral curve of the i-th dominant convex absorption peak wavelength to obtain the increment of each wavelength in the left spectral curve of the i-th dominant convex absorption peak wavelength. Based on the increment of each wavelength in the left spectral curve of the i-th dominant convex absorption peak wavelength, obtain the smoothing coefficient of the i-th dominant convex absorption peak wavelength. ; The ideality coefficient of the left spectral curve for the wavelength of the i-th dominant convex absorption peak is calculated as follows: in, The maximum peak value of the left spectral curve is the wavelength of the i-th principal convex absorption peak. λ is the first wavelength of the absorption curve of the i-th dominant convex absorption peak; exp is an exponential function with the natural constant as the base.

[0009] Preferably, the smoothing coefficient is obtained using the following method: Smoothing coefficient of the wavelength of the i-th dominant convex absorption peak The calculation method is as follows: in, The left spectral curve of the i-th principal convex absorption peak wavelength An increment of one wavelength; The left spectral curve of the i-th principal convex absorption peak wavelength Increment of each wavelength, denoted as the number of wavelengths in the left spectral curve corresponding to the wavelength of the i-th dominant convex absorption peak; norm is a linear normalization function.

[0010] Preferably, the method for obtaining the morphological ideality coefficient of the right spectral curve includes: Based on the method for obtaining the shape ideality coefficient of the left spectral curve of the i-th dominant convex absorption peak wavelength, the shape ideality coefficient of the right spectral curve of the i-th dominant convex absorption peak wavelength is obtained.

[0011] Preferably, the method for using the morphological ideality coefficient to screen the left and right spectral curves to obtain the dominant side spectral curve for each main convex absorption peak is as follows: The spectral curve with the larger shape ideality coefficient between the left and right spectral curves of the i-th dominant convex absorption peak wavelength is denoted as the dominant side spectral curve of the i-th dominant convex absorption peak.

[0012] Preferably, the method for determining the purity priority of each dominant absorption peak based on its asymmetry and the difference between its non-preferred side spectral curve and the standard spectral curve includes the following specific methods: Purity priority of the i-th dominant convex absorption peak The calculation method is as follows: in, Let be the first wavelength of the absorption curve of the i-th dominant convex absorption peak. The wavelength maximum value of the dominant side spectrum curve of the i-th main convex absorption peak; denoted by , where is the degree of asymmetry of the i-th dominant convex absorption peak; exp is an exponential function with the natural constant as its base. In order to be in Absorbance within the range A function for finding the minimum value.

[0013] Preferably, the degree of asymmetry is obtained by the following method: The expression for the standard spectral curve of the i-th principal convex absorption peak is denoted as: ; The method for calculating the asymmetry of the i-th dominant convex absorption peak is as follows: in, The number of wavelengths in the non-preferred side spectrum of the i-th dominant convex absorption peak; The non-preferred side spectrum of the i-th principal convex absorption peak Absorbance at each wavelength The standard spectrum of the i-th principal convex absorption peak Absorbance at each wavelength; This is the function for taking the absolute value.

[0014] Preferably, the difference spectrum between the spectral curve of the test solution and the standard spectral curves of all pure absorption peaks is denoted as the first residual curve of the test solution; the first residual curve of the test solution is used as the new spectral curve to obtain new pure absorption peaks and a second residual curve, and so on until there exists a constant N such that the Nth residual curve no longer contains a dominant convex absorption peak, thus obtaining the standard spectral curves of all pure absorption peaks. The specific method includes: The standard spectral curve of the main convex absorption peak corresponding to each pure absorption peak is denoted as the standard spectral curve of each pure absorption peak. The difference spectrum between the spectral curve of the test solution and the standard spectral curve of all pure absorption peaks is obtained to obtain the first residual curve of the test solution. The first residual curve of the test solution is used as the new spectral curve. The new pure absorption peaks of the new spectral curve are obtained, and the difference spectrum between the first residual curve of the test solution and the standard spectral curves of all the new pure absorption peaks is obtained; the second residual curve of the test solution is obtained. This process continues until there exists a constant N such that the Nth residual curve can no longer yield a pure absorption peak. All pure absorption peaks and their standard spectral curves were obtained.

[0015] The beneficial effects of the technical solution of this invention are as follows: This application uses a UV-Vis spectrophotometer to obtain the spectral curve of the solution to be tested, and obtains all the main convex absorption peaks and their absorption curves in the spectral curve; divides the absorption curve by the wavelength of each main convex absorption peak to obtain the left and right spectral curves of each main convex absorption peak; divides the absorption curve into left and right parts by the peak value, thereby evaluating whether the peak value is pure; analyzes the proximity of the left spectral curve to the wavelength of each main convex absorption peak and the smoothness in the rising direction to obtain the shape ideal coefficient of the left spectral curve of each main convex absorption peak; according to the spectral curve that is not affected by the overlap of multiple peaks, it approximately presents a Gaussian function shape, that is, it is smooth and approaches the wavelength of the main convex absorption peak, thereby evaluating the shape of the main convex absorption peak; obtains the shape ideal coefficient of the right spectral curve; uses the shape ideal coefficient to screen the left and right spectral curves to obtain the dominant side spectral curve of each main convex absorption peak; constructs a standard spectral curve of each main convex absorption peak based on the dominant side spectral curve; based on the asymmetry of each main convex absorption peak, and its non-dominant side spectral curve and the... The differences in standard spectral curves are used to determine the purity priority of each dominant absorption peak. After constructing a standard spectral curve for the dominant absorption peak, the approximation between the preferred side spectral curve and the standard spectral curve is analyzed. Combined with the asymmetry of the non-preferred side spectral curves, the purity priority of the preferred side spectral curve of the dominant absorption peak, unaffected by multi-peak overlap, is then determined. The purity priority is used to screen dominant absorption peaks to obtain pure absorption peaks. The difference spectrum between the spectral curve of the test solution and the standard spectral curves of all pure absorption peaks is obtained and denoted as the first residual curve of the test solution. Using the first residual curve of the test solution as a new spectral curve, new pure absorption peaks and a second residual curve are obtained, and so on, until a constant N exists such that the Nth residual curve no longer contains a dominant absorption peak, thus obtaining the standard spectral curves of all pure absorption peaks. By subtracting the pure absorption peaks from the spectral curves and repeating the above operation with the remaining peak values, all pure absorption peaks are obtained. A UV-Vis spectrophotometer performs qualitative and quantitative analysis based on the standard spectral curves of all pure absorption peaks to obtain the concentrations of all components in the test solution. The present invention aims to solve the problem of overlapping absorption peaks of multiple components in the spectral images obtained by ultraviolet-visible spectrophotometers, thereby improving the accuracy of water quality component detection. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1This is a flowchart of the steps of the water quality multi-component detection method based on ultraviolet-visible spectrophotometer of the present invention. Detailed Implementation

[0018] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of the water quality multi-component detection method based on an ultraviolet-visible spectrophotometer proposed according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0020] The following description, in conjunction with the accompanying drawings, details the specific scheme of the water quality multi-component detection method based on an ultraviolet-visible spectrophotometer provided by this invention.

[0021] Please see Figure 1 The diagram illustrates a flowchart of a method for detecting multiple components of water quality based on a UV-Vis spectrophotometer, according to an embodiment of the present invention. The method includes the following steps: Step S001: Obtain the spectral curve of the solution to be tested using a UV-Vis spectrophotometer, and acquire all the main convex absorption peaks and their absorption curves in the spectral curve.

[0022] It should be noted that the UV-Vis spectrophotometer is based on the fact that different components in water absorb light only under UV and visible light irradiation at specific wavelengths. By measuring the intensity of the absorbed light, the spectral curve of the test solution is obtained, and then the absorption peaks are obtained from the spectral curve. By comparing the wavelength, shape, and absorbance ratio of the absorption peaks with known substances in a standard spectral library, the substance corresponding to each absorption peak is obtained. By preparing solutions of different concentrations of known substances and measuring their absorbance, and combining the Lambert-Beer law (i.e., absorbance is proportional to concentration), the absorbance of the known concentration solution is compared with the absorbance of the substance in the spectral curve of the test solution to obtain the components and their concentrations in the test solution.

[0023] Based on the above, this embodiment uses a UV-Vis spectrophotometer to obtain the spectral curve of the solution to be tested, and obtains all the main convex absorption peaks and their absorption curves in the spectral curve.

[0024] Specifically, the spectral curve of the test solution is obtained using a UV-Vis spectrophotometer, and all main convex absorption peaks and their absorption curves are acquired, including: Collect raw water samples, quantitatively transfer and dilute the raw water samples tenfold to obtain the test solution; The solution to be tested is injected into a cuvette and placed in a UV-Vis spectrophotometer. A full-band scan is performed using light from 200 to 700 nm to obtain the spectral curve of the solution to be tested. The ultraviolet-visible spectrophotometer acquires all the maxima and minima of the spectral curve and marks them as absorption peaks, thus obtaining several main convex absorption peaks of the spectral curve. The spectral curve between the two minimum wavelengths on either side of each dominant absorption peak is denoted as the absorption curve of each dominant absorption peak.

[0025] It should be noted that the horizontal axis of the absorption curve and the spectral curve represents wavelength, and the vertical axis represents absorbance.

[0026] Step S002: Divide the absorption curve of each convex absorption peak by wavelength to obtain the left and right spectral curves of each convex absorption peak; analyze the proximity of the left spectral curve to the wavelength of each convex absorption peak and the smoothness in the rising direction to obtain the shape ideality coefficient of the left spectral curve of each convex absorption peak; obtain the shape ideality coefficient of the right spectral curve; use the shape ideality coefficient to filter the left and right spectral curves to obtain the preferred side spectral curve of each convex absorption peak.

[0027] It should be noted that the wavelengths absorbed by each component in a mixed solution differ, meaning each absorption peak corresponds to a single component. However, since the spectral curve of a single component exhibits a Gaussian function shape, if the wavelengths of the absorption peaks of multiple components in a mixed solution are similar, the absorption peaks of multiple components will overlap, thus affecting the qualitative analysis of each absorption peak.

[0028] It should be further noted that, since the absorption wavelengths of different components, even if they are similar, still have certain differences, the overlap of absorption peaks tends to be more likely to occur when the non-peak portion of the absorption peak curve overlaps with other absorption peaks. When only two peaks overlap, for any absorption peak, one side of the absorption curve on either side will be less affected by the overlap. When multiple peaks overlap, the absorption curve on the side of the outermost absorption peak is least affected by the overlap. Therefore, this embodiment, based on the principle that the closer to the edge of the overlap, the more realistic it is, gradually subtracts the overlapping absorption peak curves, thereby cyclically splitting the spectral curves of the test solution to obtain the pure spectral curves of all components.

[0029] Based on the above, this embodiment first divides the absorption curve of each main convex absorption peak by wavelength to obtain the left and right spectral curves of each main convex absorption peak.

[0030] Specifically, the method for dividing the absorption curve by the wavelength of each dominant absorption peak to obtain the left and right spectral curves of each dominant absorption peak is as follows: For the i-th dominant convex absorption peak, a standard coordinate system for the i-th dominant convex absorption peak is constructed with the first wavelength of the absorption curve of the i-th dominant convex absorption peak as the origin, the horizontal axis as the wavelength, and the vertical axis as the absorbance. The curve is segmented from the leftmost wavelength of the absorption curve of the i-th convex absorption peak to the wavelength including the i-th convex absorption peak, and then projected onto the standard coordinate system of the i-th convex absorption peak to obtain the left spectral curve of the i-th convex absorption peak. The absorption curve of the i-th convex absorption peak is segmented from the wavelength after the convex absorption peak to the rightmost wavelength. After the coordinates are reversed, the segments are projected onto the standard coordinate system of the i-th convex absorption peak to obtain the right spectral curve of the i-th convex absorption peak. It should be noted that the coordinates of the segments are swapped so that the last wavelength becomes the first wavelength, the second to last wavelength becomes the second wavelength, and so on.

[0031] It should be noted that the absorption peaks at the edge of overlap are less affected by the overlap on one side. Ideally, the waveform of an absorption peak is a bell-shaped curve that approximates a Gaussian function. This bell-shaped curve is smooth as the wavelength increases or decreases. However, when the spectral curves of absorption peaks overlap, the addition of the peak tails of other absorption peaks disrupts the smoothness of the spectral curves. At the same time, if the peak tails of an absorption peak overlap the peak tails of other absorption peaks, then the wavelength distance from the main convex absorption peak is greater at the same absorbance.

[0032] Based on the above, this embodiment analyzes the proximity of the left and right spectral curves of each convex absorption peak to the wavelength of the convex absorption peak and the smoothness in the rising direction to obtain the shape ideal coefficient of the left and right spectral curves of each convex absorption peak. Then, the preferred side spectral curve of each convex absorption peak is selected using the shape ideal coefficient.

[0033] Preferably, the approximation of the left spectral curve to the wavelength of each convex absorption peak and its smoothness in the ascending direction are analyzed to obtain the shape ideality coefficient of the left spectral curve for each convex absorption peak; the shape ideality coefficient of the right spectral curve is obtained; the left and right spectral curves are screened using the shape ideality coefficients to obtain the preferred side spectral curve for each convex absorption peak, including: By integrating the absorbance and wavelength of the left spectral curve at the wavelength of the i-th principal convex absorption peak, the half-peak area of ​​the left spectral curve at the wavelength of the i-th principal convex absorption peak is obtained. ; After calculating the absorbance-wavelength integral of the left spectral curve at the wavelength of the i-th convex absorption peak, the maximum and minimum values ​​of the absorbance-wavelength integral of the left spectral curve at the wavelength of the i-th convex absorption peak are normalized using the integral results of the left spectral curves of all convex absorption peaks, thus obtaining the half-peak area of ​​the left spectral curve at the wavelength of the i-th convex absorption peak. ; Perform a first-order difference calculation on the left spectral curve of the i-th dominant convex absorption peak wavelength to obtain the increment of each wavelength in the left spectral curve of the i-th dominant convex absorption peak wavelength. Based on the increment of each wavelength in the left spectral curve of the i-th dominant convex absorption peak wavelength, obtain the smoothing coefficient of the i-th dominant convex absorption peak wavelength. ; Smoothing coefficient of the wavelength of the i-th dominant convex absorption peak The calculation method is as follows: in, The left spectral curve of the i-th principal convex absorption peak wavelength An increment of one wavelength; The left spectral curve of the i-th principal convex absorption peak wavelength Increment of each wavelength, is the number of wavelengths in the left spectral curve of the i-th dominant convex absorption peak; norm is the linear normalization function; The ideality coefficient of the left spectral curve for the wavelength of the i-th dominant convex absorption peak is calculated as follows: in, The maximum peak value of the left spectral curve is the wavelength of the i-th principal convex absorption peak. is the first wavelength of the absorption curve of the i-th dominant convex absorption peak; exp is an exponential function with the natural constant as the base, used to inversely normalize the morphological ideal coefficient; It should be noted that the peak area represents the area of ​​one side of the convex absorption peak. The smaller the area, the greater the variation in the spectral curve of that absorption peak. This indicates that it is more likely to have only the tail of the i-th convex absorption peak, without interference from the tails of other convex absorption peaks. Furthermore, if the difference in absorbance increment between two adjacent wavelengths in the left spectral curve of the convex absorption peak with increasing wavelength is significant... The smaller the value, the smoother the left spectral curve of the i-th main convex absorption peak, the less interference from the peak tails of other absorption peaks, and the more ideal the shape. In other words, the larger the value of the shape ideality coefficient is.

[0034] Furthermore, based on the method for obtaining the shape ideality coefficient of the left spectral curve of the i-th main convex absorption peak wavelength, the shape ideality coefficient of the right spectral curve of the i-th main convex absorption peak wavelength is obtained. Furthermore, the spectral curve with the larger shape ideality coefficient between the left and right spectral curves of the i-th main convex absorption peak wavelength is denoted as the dominant side spectral curve of the i-th main convex absorption peak. It should be noted that if the shape ideality coefficients of the left and right spectral curves of the wavelength of the i-th dominant convex absorption peak are the same, then the left spectral curve of the wavelength of the i-th dominant convex absorption peak is assumed to be the dominant side spectral curve of the i-th dominant convex absorption peak.

[0035] Step S003: Construct a standard spectral curve for each convex absorption peak based on the preferred side spectral curve; obtain the purity priority of each convex absorption peak based on the asymmetry of each convex absorption peak and the difference between its non-preferred side spectral curve and the standard spectral curve; use the purity priority to screen the convex absorption peaks to obtain pure absorption peaks.

[0036] It should be noted that after obtaining the dominant spectral curve of each convex absorption peak, this embodiment is based on the principle that the closer the spectral curve is to the edge in the multi-component overlapping spectral curve, the smaller the degree of overlap and the higher the authenticity. The individual convex absorption peaks are gradually separated from the spectral curve of the test solution to obtain the pure absorption peak and its spectral curve. The spectral curve of each convex absorption peak is approximately a Gaussian function. When the peak value, center and a sufficient number of rising / falling edges of a Gaussian function curve are known, the complete curve of the Gaussian function can be deduced.

[0037] Based on the above, this embodiment reconstructs the standard spectral curve of each convex absorption peak according to the dominant side spectral curve of each convex absorption peak.

[0038] Specifically, the method for constructing the standard spectral curve for each dominant absorption peak based on its dominant-side spectral curve is as follows: The wavelength of the i-th dominant convex absorption peak is taken as the center of the standard spectral curve of the i-th dominant convex absorption peak. The absorbance at the wavelength of the i-th principal convex absorption peak is taken as the peak value of the standard spectral curve of the i-th principal convex absorption peak. ; The standard deviation of the dominant-side spectrum of the i-th dominant absorption peak is calculated using absorbance as a weight, and denoted as the estimated standard deviation of the standard spectrum of the i-th dominant absorption peak. ; The standard spectral curve of the i-th dominant convex absorption peak The expression is: It should be noted that the structure of the above expression is the existing Gaussian function expression, which is a well-known technique, and will not be described in detail in this embodiment.

[0039] It should be noted that, based on the foregoing, when multiple convex absorption peaks overlap, the peak tails of convex absorption peaks closer to the edge are less affected by the overlap. That is, the absorbance of the dominant side spectrum curve of the convex absorption peak closer to the edge is closer to 0, so it is minimally affected by the overlap. When the other side is affected by the overlap, the difference in morphology between the two sides of the convex absorption peak is greater. That is, the difference between the curve shape of the non-dominant side spectrum curve and the reconstructed standard spectrum curve is greater. Therefore, when gradually subtracting the spectrum curve of the edge convex absorption peak, it has a higher priority for being subtracted.

[0040] Based on the above, this embodiment obtains the purity priority of each main convex absorption peak according to the asymmetry of each main convex absorption peak and the difference between its non-preferred side spectral curve and the standard spectral curve.

[0041] Preferably, the purity priority of each convex absorption peak is obtained based on the asymmetry of each peak and the difference between its non-preferred side spectral curve and the standard spectral curve, including: Purity priority of the i-th dominant convex absorption peak The calculation method is as follows: in, Let be the first wavelength of the absorption curve of the i-th dominant convex absorption peak. The wavelength maximum value of the dominant side spectrum curve of the i-th main convex absorption peak; The degree of asymmetry of the i-th dominant convex absorption peak; The number of wavelengths in the non-preferred side spectrum of the i-th dominant convex absorption peak; The non-preferred side spectrum of the i-th principal convex absorption peak Absorbance at each wavelength The standard spectrum of the i-th principal convex absorption peak The absorbance at each wavelength; exp is an exponential function with the natural constant as its base. For the absolute value function, In order to be in Absorbance within the range The minimum value is a function, and the norm function is a linear normalization function. In this embodiment, normalization is achieved by taking the ratio of the calculated result within the function to the maximum absorbance of all main convex absorption peaks.

[0042] It should be noted that the above non-preferred side spectral curve is the other spectral curve besides the preferred side spectral curve among the left and right spectral curves of the i-th main convex absorption peak. It should be noted that, Take the absorbance from the dominant side spectrum of the i-th main convex absorption peak. The function with the minimum value indicates that the spectral curve is less affected by overlapping peaks. In other words, the more likely the spectral curve of the dominant side is located at the edge of the overlapping of the multi-component spectral curves, the higher its priority for being subtracted as a pure absorption peak. Since the standard spectral curve is a Gaussian function, meaning it is perfectly symmetrical on both sides, the symmetry between the non-dominant spectral curve and the standard spectral curve can be indicated by the residual between the non-dominant spectral curve and the dominant spectral curve. The larger the residual, the more asymmetrical the two sides are, meaning the spectral curve of the dominant side is less affected by overlapping peaks, and the higher its priority for being subtracted as a pure absorption peak.

[0043] Furthermore, the specific method for obtaining pure absorption peaks by prioritizing the main convex absorption peaks based on purity is as follows: The purity priority of all main convex absorption peaks is thresholded using the Otsu threshold algorithm to obtain the portions with higher purity priority and the portions with lower purity priority. The dominant convex absorption peak in the portion with higher purity priority is designated as the pure absorption peak.

[0044] It should be noted that the Otsu threshold algorithm is a well-known existing technology, and will not be described in detail in this embodiment.

[0045] Step S004: Obtain the difference spectrum between the spectral curve of the test solution and the standard spectral curve of all pure absorption peaks, and record it as the first residual curve of the test solution; take the first residual curve of the test solution as the new spectral curve, and obtain the new pure absorption peak and the second residual curve, and so on until there exists a constant N such that there is no longer a main convex absorption peak in the Nth residual curve, and obtain the standard spectral curve of all pure absorption peaks.

[0046] It should be noted that the pure absorption peaks obtained above represent the outermost convex absorption peaks when the absorption peaks of multiple components overlap in water, and are least affected by the overlap. The spectral curve of a single component has an approximate Gaussian function shape, i.e., the standard spectral curve obtained above. By subtracting the standard spectral curve of the pure absorption peak from the test solution, the spectral curves of the components affected by the overlap of absorption peaks can be extracted first. The standard spectral curves can then be used to obtain the corresponding substances and concentrations of the components through qualitative and quantitative analysis. After subtracting the pure absorption peaks, other convex absorption peaks that were originally affected by the pure absorption peaks will be exposed. These absorption peaks can then be used as new outermost absorption peaks. By screening for new outermost absorption peaks and subtracting them, and repeating this step, all pure absorption peaks and their standard spectral curves can be obtained.

[0047] Based on the above, this embodiment subtracts the difference spectrum of the standard spectrum of all pure absorption peaks from the spectral curve of the test solution, and uses it as a new spectral curve to screen for new pure absorption peaks, finally obtaining all pure absorption peaks and their standard spectral curves.

[0048] Preferably, the difference spectrum between the spectral curve of the test solution and the standard spectral curves of all pure absorption peaks is obtained and denoted as the first residual curve of the test solution; the first residual curve of the test solution is used as the new spectral curve, and new pure absorption peaks and second residual curves are obtained, and so on, until there exists a constant N such that the Nth residual curve no longer contains a dominant convex absorption peak, thus obtaining the standard spectral curves of all pure absorption peaks, including: The standard spectral curve of the main convex absorption peak corresponding to each pure absorption peak is denoted as the standard spectral curve of each pure absorption peak. The difference spectrum between the spectral curve of the test solution and the standard spectral curve of all pure absorption peaks is obtained to obtain the first residual curve of the test solution. It should be noted that after calculating the difference spectrum between the spectral curve and the standard spectral curve, if there are data points with absorbance less than 0, the absorbance of those data points should be forcibly set to 0. The first residual curve of the test solution is used as the new spectral curve. The new pure absorption peaks of the new spectral curve are obtained, and the difference spectrum between the first residual curve of the test solution and the standard spectral curves of all the new pure absorption peaks is obtained; the second residual curve of the test solution is obtained. This process continues until there exists a constant N such that the Nth residual curve can no longer yield a pure absorption peak. Thus, all the pure absorption peaks and their standard spectral curves were obtained.

[0049] It should be noted that the difference spectrum method for obtaining the spectrum is a well-known existing technique, and will not be described in detail in this embodiment.

[0050] Step S005: The UV-Vis spectrophotometer performs qualitative and quantitative analysis based on the standard spectral curves of all pure absorption peaks to obtain the concentration of all components in the test solution.

[0051] Specifically, the UV-Vis spectrophotometer performs qualitative analysis on each pure absorption peak based on its wavelength, shape, absorbance ratio, etc., against known substances in the standard spectral library to obtain the composition of each pure absorption peak. Standard solutions of different concentrations were prepared from the standard spectral library according to the components of each pure absorption peak. In this example, 0.2 mg / ml, 0.4 mg / ml, 0.6 mg / ml, 0.8 mg / ml, and 1.0 mg / ml were used as examples. All standard solutions of the same concentration were scanned using a UV-Vis spectrophotometer to obtain the absorbance of the standard solution of each concentration of the component. Based on the concentration and absorbance, a standard curve for each component with a pure absorption peak is plotted, with concentration on the horizontal axis and absorbance on the vertical axis. The standard curve is a straight line passing through the origin. The absorbance of each pure absorption peak in the spectral curve of the test solution is compared with the standard curve to obtain the composition of each pure absorption peak in the test solution. Thus, all components and their concentrations in the solution to be tested are obtained.

[0052] It should be noted that the embodiments used in this example The model only represents negative correlations and constraints. The model output results are in... Within the interval, This is the input to this model; in specific implementations, it can be replaced with other models that have the same purpose. This embodiment is merely an example. The description will be based on a model, without making any specific limitations.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for multi-component water quality detection based on ultraviolet-visible spectrophotometer, characterized in that, The method includes the following steps: The spectral curve of the solution to be tested was obtained using a UV-Vis spectrophotometer, and all the main convex absorption peaks and their absorption curves in the spectral curve were obtained. The absorption curves of each convex absorption peak are divided according to its wavelength, resulting in a left and right spectral curve for each peak. The approximation of the left spectral curve to the wavelength of each peak and its smoothness in the rising direction are analyzed to obtain the shape ideality coefficient of the left spectral curve for each peak. The shape ideality coefficient of the right spectral curve is also obtained. The left and right spectral curves are then selected using the shape ideality coefficients to obtain the preferred spectral curve for each peak. A standard spectral curve for each convex absorption peak is constructed based on the preferred side spectral curve; the purity priority of each convex absorption peak is obtained based on the asymmetry of each convex absorption peak and the difference between its non-preferred side spectral curve and the standard spectral curve; the convex absorption peaks are screened using the purity priority to obtain pure absorption peaks. Obtain the difference spectrum between the spectral curve of the test solution and the standard spectral curve of all pure absorption peaks, and record it as the first residual curve of the test solution. Use the first residual curve of the test solution as the new spectral curve, and obtain the new pure absorption peak and the second residual curve. Continue in this way until there exists a constant N such that there is no main convex absorption peak in the Nth residual curve, and obtain the standard spectral curve of all pure absorption peaks. The UV-Vis spectrophotometer performs qualitative and quantitative analysis based on the standard spectral curves of all pure absorption peaks to obtain the concentration of all components in the test solution. The method for determining the purity priority of each dominant absorption peak based on its asymmetry and the difference between its non-preferred side spectral curve and the standard spectral curve includes the following specific methods: Purity priority of the i-th dominant convex absorption peak The calculation method is as follows: in, Let be the first wavelength of the absorption curve of the i-th dominant convex absorption peak. The wavelength maximum value of the dominant side spectrum curve of the i-th main convex absorption peak; denoted by , where is the degree of asymmetry of the i-th dominant convex absorption peak; exp is an exponential function with the natural constant as its base. In order to be in Absorbance within the range A function of minimum value; The degree of asymmetry is specifically obtained as follows: The expression for the standard spectral curve of the i-th principal convex absorption peak is denoted as: ; The method for calculating the asymmetry of the i-th dominant convex absorption peak is as follows: in, The number of wavelengths in the non-preferred side spectrum of the i-th dominant convex absorption peak; The non-preferred side spectrum of the i-th principal convex absorption peak Absorbance at each wavelength The standard spectrum of the i-th principal convex absorption peak Absorbance at each wavelength; This is the function for taking the absolute value.

2. The method for multi-component water quality detection based on a UV-Vis spectrophotometer according to claim 1, characterized in that, The specific method for obtaining all the main convex absorption peaks and their absorption curves in the spectral curve is as follows: The ultraviolet-visible spectrophotometer acquires all the maxima and minima of the spectral curve and marks them as absorption peaks, thus obtaining several main convex absorption peaks of the spectral curve. The spectral curve between the two minimum wavelengths on either side of each dominant absorption peak is denoted as the absorption curve of each dominant absorption peak.

3. The method for multi-component water quality detection based on a UV-Vis spectrophotometer according to claim 1, characterized in that, The method for dividing the absorption curve by the wavelength of each main convex absorption peak to obtain the left and right spectral curves of each main convex absorption peak includes the following specific methods: For the i-th dominant convex absorption peak, a standard coordinate system for the i-th dominant convex absorption peak is constructed with the first wavelength of the absorption curve of the i-th dominant convex absorption peak as the origin, the horizontal axis as the wavelength, and the vertical axis as the absorbance. The curve is segmented from the leftmost wavelength of the absorption curve of the i-th convex absorption peak to the wavelength including the i-th convex absorption peak, and then projected onto the standard coordinate system of the i-th convex absorption peak to obtain the left spectral curve of the i-th convex absorption peak. The absorption curve of the i-th convex absorption peak is segmented into sections from the wavelength following the convex absorption peak to the rightmost wavelength. After coordinate reversal, these segments are projected onto the standard coordinate system of the i-th convex absorption peak to obtain the right spectral curve of the i-th convex absorption peak.

4. The method for multi-component water quality detection based on a UV-Vis spectrophotometer according to claim 1, characterized in that, The analysis of the approximation of the left spectral curve to the wavelength of each main convex absorption peak and its smoothness in the ascending direction yields the shape ideality coefficient of the left spectral curve for each main convex absorption peak. The specific methods include: After calculating the absorbance-wavelength integral of the left spectral curve at the wavelength of the i-th convex absorption peak, the maximum and minimum values ​​of the absorbance-wavelength integral of the left spectral curve at the wavelength of the i-th convex absorption peak are normalized using the integral results of the left spectral curves of all convex absorption peaks, thus obtaining the half-peak area of ​​the left spectral curve at the wavelength of the i-th convex absorption peak. ; Perform a first-order difference calculation on the left spectral curve of the i-th dominant convex absorption peak wavelength to obtain the increment of each wavelength in the left spectral curve of the i-th dominant convex absorption peak wavelength. Based on the increment of each wavelength in the left spectral curve of the i-th dominant convex absorption peak wavelength, obtain the smoothing coefficient of the i-th dominant convex absorption peak wavelength. ; The ideality coefficient of the left spectral curve for the wavelength of the i-th dominant convex absorption peak is calculated as follows: in, The maximum peak value of the left spectral curve is the wavelength of the i-th principal convex absorption peak. λ is the first wavelength of the absorption curve of the i-th dominant convex absorption peak; exp is an exponential function with the natural constant as the base.

5. The method for multi-component water quality detection based on a UV-Vis spectrophotometer according to claim 4, characterized in that, The smoothing coefficient is specifically obtained as follows: Smoothing coefficient of the wavelength of the i-th dominant convex absorption peak The calculation method is as follows: in, The left spectral curve of the i-th principal convex absorption peak wavelength An increment of one wavelength; The left spectral curve of the i-th principal convex absorption peak wavelength Increment of each wavelength, denoted as the number of wavelengths in the left spectral curve corresponding to the wavelength of the i-th dominant convex absorption peak; norm is a linear normalization function.

6. The method for multi-component water quality detection based on a UV-Vis spectrophotometer according to claim 1, characterized in that, The specific method for obtaining the morphological ideality coefficient of the right spectral curve is as follows: Based on the method for obtaining the shape ideality coefficient of the left spectral curve of the i-th dominant convex absorption peak wavelength, the shape ideality coefficient of the right spectral curve of the i-th dominant convex absorption peak wavelength is obtained.

7. The method for multi-component water quality detection based on a UV-Vis spectrophotometer according to claim 1, characterized in that, The method for using the morphological ideality coefficient to screen the left and right spectral curves to obtain the dominant side spectral curve for each main convex absorption peak is as follows: The spectral curve with the larger shape ideality coefficient between the left and right spectral curves of the i-th dominant convex absorption peak wavelength is denoted as the dominant side spectral curve of the i-th dominant convex absorption peak.

8. The method for multi-component water quality detection based on a UV-Vis spectrophotometer according to claim 1, characterized in that, The difference spectrum between the spectral curve of the test solution and the standard spectral curve of all pure absorption peaks is denoted as the first residual curve of the test solution. Using the first residual curve of the test solution as the new spectral curve, new pure absorption peaks and a second residual curve are obtained, and so on, until a constant N exists such that the Nth residual curve no longer contains a dominant absorption peak, thus obtaining the standard spectral curve of all pure absorption peaks. The specific method includes: The standard spectral curve of the main convex absorption peak corresponding to each pure absorption peak is denoted as the standard spectral curve of each pure absorption peak. The difference spectrum between the spectral curve of the test solution and the standard spectral curve of all pure absorption peaks is obtained to obtain the first residual curve of the test solution. The first residual curve of the test solution is used as the new spectral curve. The new pure absorption peaks of the new spectral curve are obtained, and the difference spectrum between the first residual curve of the test solution and the standard spectral curves of all the new pure absorption peaks is obtained; the second residual curve of the test solution is obtained. This process continues until there exists a constant N such that the Nth residual curve can no longer yield a pure absorption peak. All pure absorption peaks and their standard spectral curves were obtained.

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