CN109799203A - A kind of wide-range high-precision spectral method of detection of COD in water body concentration - Google Patents
A kind of wide-range high-precision spectral method of detection of COD in water body concentration Download PDFInfo
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Abstract
The invention proposes a kind of wide-range high-precision spectral method of detection of COD in water body concentration, include: with ultraviolet specrophotometer or the spectral measurement device with corresponding function measures N number of standard COD solution example with concentration gradient, calculates absorbance value of the full spectroscopic data of N group at each wavelength；Go out the functional relation of absorbance and COD concentration at each wavelength by least square method the Fitting Calculation；N wavelength appropriate is chosen, as modeling wavelength；It calculates separately at n wavelength, the linear relationship of each wavelength corresponding optimum measurement concentration range internal absorbance and concentration；Absorbance of the survey calculation unknown concentration COD solution at its n wavelength；Select the corresponding optimal measurement wavelength of the COD solution concentration；Calculate the COD concentration value of unknown solution.The present invention handles analytical technology with full spectroscopic data, can be high-precision simultaneously in guarantee, is significantly expanded the measurement of concetration range of COD solution.
Description
Technical field
The present invention relates to the detection methods of Water quality detected field more particularly to COD concentration and environmental optics to detect skill
A kind of art field, and in particular, to wide-range high-precision spectral method of detection of COD in water body concentration.
Background technique
COD (COD) refers under certain condition, when reducing substances are aoxidized by strong oxidizer in water body, is consumed
Oxidant amount, be converted into the concentration of oxygen in terms of mg/L, be characterize water in reducing substances composite target.In recent years,
Chinese national economy is quickly grown, but problem of environmental pollution is also got worse simultaneously, especially water pollution the problem of.COD
Concentration index can be used for judging the relative amount of organic matter in water body, be most important organic contamination overall target in environmental monitoring
One of.Water-quality COD detection in the country's is largely according to the chemical method of national standard or its improved method at present.Its measurement process
Need to heat resolution, titration, required chemical reagent type is more, there are secondary pollution, complicated for operation, time-consuming, analysis speed is slow,
The problem of stability difference.
UV-Visible absorption spectrum is built upon a kind of molecule using measured matter on lambert-Beer law
Or the method that the degree of absorption of ion pair characteristic electromagnetic radiation carries out quantitative analysis, it is a kind of optical detecting method of pure physics,
Without chemical reagent, without secondary pollution.In recent years, having carried out a large amount of related UV absorption water quality inspection technique both at home and abroad
Research.COD concentration is mostly measured using absorbance at 254nm at present, this method is simple and easy, but due to the resolution ratio by instrument
It is not high to generate the factors influence such as non-linear in the measurement of high concentration section with application lambert-Beer law, Single wavelength or spy is used only
The absorbance value for determining multi-wavelength calculates COD concentration, and measurement range is small, and precision is low.
If desired the COD content of low concentration or high concentration is measured, first is that the mode by adjusting light path is realized, it can basis
The sample cell of specific light path is selected in user demand.It is such as small using the apparatus measures range of 10mm path-length cell, it is 10-
200mg/L, precision is higher, accuracy 1mg/L；It is big using the apparatus measures range of 1mm path-length cell, it is 100-
2000mg/L, but precision is lower, accuracy 10mg/L.Method by changing light path can drop while range extension
The detection accuracy of low instrument；And to measure the biggish water quality of concentration span scope, need to increase survey with more instruments
Measure cost.Second is that the mode by adjusting light source power or the flashing times of light source realizes the expansion to measurement range, but this side
Method can not accomplish the spectral absorbance data only obtained by one-shot measurement for the sample of unknown concentration COD, calculate accurately
COD concentration value.
Summary of the invention
For the defects in the prior art, the object of the present invention is to provide a kind of detection speed fastly, is not necessarily to chemical reagent, nothing
The sample cell or adjustment light source, the full spectrum analysis detection method of COD concentration based on ultravioletvisible absorption method of adjustment light path are needed to change,
Measurement range can be expanded while guaranteeing precision.
The spectral method of detection of the wide-range high-precision of a kind of pair of COD in water body concentration is provided according to the present invention, comprising:
Modeling process:
Preparing N group has the COD standard solution of a certain concentration gradient as modeling sample, uses ultraviolet-uisible spectrophotometer
Or spectral measurement device measures the absorbance of each modeling sample (such as 200nm-600nm) within a certain spectral range, referred to as
For full spectroscopic data；
Go out absorbance and COD standard at each wavelength of the modeling sample by the approximating methods the Fitting Calculation such as least square method
The functional relation of solution concentration；
Further according to absorbance and concentration at each wavelength the linearity choose n wavelength therein as model wavelength (n >
2)；The modeling wavelength chooses the COD concentration model that linearly dependent coefficient is greater than 0.99 (can be other values according to required precision)
Enclose as can linear concentration range, by the modeling wavelength of selection according to its it is corresponding can linear concentration range from it is small to
Big number consecutively is λ1, λ2... ..., λn, wherein to ensure λ1The maximum concentration surveyed at wavelength is equal to λ2Being surveyed at wavelength
Minimum concentration, and so on, enable measurement range throughout from small to large；
I.e. wavelength is corresponding most thus for absorbance concentration range corresponding with COD concentration relationship optimum linear section at each wavelength
It is good can linear concentration range；
Each wavelength it is corresponding most preferably can the threshold value of linear concentration range be the minimum concentration of the concentration section and most highly concentrated
Degree, calculate it is described modeling wavelength can linear concentration range maximum concentration absorbance and minimum concentration absorbance, by most
Small square law calculate the modeling wavelength respectively can absorbance and concentration in linear concentration range linear relationship；
Calculate it is described modeling wavelength can linear concentration range maximum concentration absorbance and minimum concentration absorbance, lead to
Over-fitting method the Fitting Calculation go out the modeling wavelength respectively can absorbance in linear concentration range and concentration it is linear
Relationship；
Measure unknown concentration COD solution, comprising: the full spectroscopic data for measuring the unknown concentration COD solution, according to
The n modeling wavelength selected in the modeling sample, calculate absorbance of the unknown concentration COD solution at n wavelength；Choosing
Select the corresponding optimal measurement wavelength of the unknown concentration COD solution concentration；Pass through the concentration and absorbance at the modeling wavelength
Fitting function relationship, calculate the COD concentration value of the unknown solution.
Measurement process:
Measuring unknown concentration COD solution methods includes:
The instrument parameter setting of measurement is identical as modeling process, measures the full spectroscopic data of the unknown concentration COD solution,
According to the n selected in the modeling sample the modeling wavelength, extinction of the unknown concentration COD solution at n wavelength is calculated
Spend A1,A2... ..., An；
Select the corresponding optimal measurement wavelength of the unknown concentration COD solution concentration；By the unknown concentration COD solution
Absorbance A1,A2... ..., AnSuccessively wavelength X is modeled with described in the modeling sample1, λ2... ..., λnThe maximum concentration at place is inhaled
Luminosity is compared, when the absorbance A of the unknown concentration COD solutionmAt modeling wavelength X m (1≤m≤n) wavelength
Maximum concentration absorbance when, the λmWavelength is the optimal measurement wavelength of the solution；
By the fitting function relationship of concentration and absorbance at the modeling wavelength, the COD for calculating unknown solution is dense
Angle value.
Preferably, the absorption spectrum of the template sample, wave-length coverage are measured using UV, visible light spectrophotometric system
200-600nm, spectral bandwidth are less than 10nm, light path 10mm.
Preferably, using the full spectroscopic data of absorbance of modeling sample described in spectral measurement device systematic survey, the light
Spectrometry device includes light source, colimated light system, sample cell, convergence yoke and spectrometer, wherein the light source issues light, passes through
The incident sample cell of the colimated light system, is emitted, using the meeting from the sample cell after being absorbed by the modeling sample
It is divided and detects by spectrometer after poly- system.
Preferably, the different COD concentration gradient solution of configuration N group, which include: that preparation is N number of as modeling sample, has certain C OD
The standard solution of concentration gradient is as modeling sample, and to each described modeling sample duplicate measurements M times, it is dense to obtain the different COD of N group
The full spectroscopic data of degree calculates M average values of the full spectroscopic data at each wavelength in every group, and it is dense to obtain the different COD of N group
The full spectroscopic data of degree.
Preferably, according to formula, light intensity value of the modeling sample at each wavelength described in N group various concentration, which is calculated, is
I,
Wherein A is absorbance value, I0Luminous intensity when for COD concentration being zero；
According to lambert-Beer law, absorbance value of the modeling sample at each wavelength described in N group various concentration is calculated,
A=KCL
Wherein K is absorption constant, and C is COD concentration value, and L is optical path length.
Preferably, the modeling wavelength refers at COD high concentration range, small using absorbance change under comparable sodium gradient
Wavelength, at COD low strength range, using the big wavelength of absorbance change under comparable sodium gradient.
Preferably, it executes according to the following steps:
S1, Potassium Hydrogen Phthalate is selected to be configured to COD standard solution of the N group with a certain concentration gradient as modeling sample
Product measure the absorption spectrum of each modeling sample, and wave-length coverage 200-600nm, spectral bandwidth is less than 10nm, to the modeling
Sample duplicate measurements M times obtains the full spectroscopic data of the different COD concentration of N group；
S2, in every group, M full average values of the spectroscopic data at each wavelength, the spectrum number as this group of COD concentration are calculated
According to；
S3, absorbance value of the modeling sample at each wavelength described in N group various concentration is calculated；
Specifically:
According to formula, it is I that light intensity value of the N group various concentration sample at each wavelength, which is calculated,
Wherein A is absorbance value, I0Luminous intensity when for COD concentration being zero；
According to lambert-Beer law, absorbance value of the N group various concentration sample at each wavelength is calculated；
A=KCL
Wherein K is absorption constant, and C is COD concentration value, and L is optical path length.
As shown in Figure 2, it can be seen that COD solution not only has absorption at 254nm, has suction at wavelength 220nm to 300nm sections
It receives, and wavelength is different, corresponding K value is different, causes the absorbance of each wavelength at the same concentration different.
S4, according to all band absorbance value of various concentration COD standard solution, it is each out by least square method the Fitting Calculation
The functional relation of absorbance and COD concentration at wavelength；
S5, n wavelength is chosen, as modeling wavelength, absorbance and the best line of COD concentration relationship at each modeling wavelength
The property corresponding COD concentration range of section be the modeling wave it is corresponding most preferably can linear COD concentration range, by each modeling
Wavelength according to it is corresponding it is described most preferably can linear COD concentration range to number from small to large be λ1, λ2…λn；Hereby it is achieved that surveying
The expansion of range is measured, while ensure that the precision of measurement.
The modeling wavelength most preferably can linear COD concentration range to refer to that the modeling wavelength chooses linearly dependent coefficient big
COD concentration range conduct in 0.99 can survey concentration range；
S6, it is each it is described modeling wavelength it is corresponding most preferably can linear concentration range threshold value be it is described most preferably can be linear
The minimum concentration and maximum concentration of concentration range, calculate the n modeling wavelength of selection surveys the most highly concentrated of concentration range
Absorbance and minimum concentration absorbance value are spent, calculating the n modeling wavelength by least square method can survey respectively described
The linear relationship of absorbance and concentration in concentration range；
Wherein, by the correspondences of the described modeling wavelength of n can linear concentration range maximum concentration absorbance (Ah1,
Ah2... ..., Ahn) and minimum concentration absorbance (Al1, Al2... ..., Aln), as selection range when detecting unknown COD concentration
Foundation.
S7, using unknown concentration COD solution as test sample, the full spectroscopic data of test sample is measured, according to selected
N modeling wavelength calculate unknown concentration COD solution at its n wavelength using the absorbance calculation formula in S3
Absorbance (A1,A2... ..., An)；
S8, the corresponding optimal measurement wavelength of the selection test specimen C OD solution concentration, refer to the suction of the test sample
Luminosity A1,A2... ..., AnSuccessively wavelength X is modeled with described in the modeling sample1, λ2... ..., λnThe maximum concentration extinction at place
Degree is compared, when the absorbance A of the test samplemLess than the modeling wavelength XmWhen maximum concentration absorbance at wavelength,
The modeling sample λmWavelength is the optimal measurement wavelength of the solution.
S9, according to absorbance in S6 and concentration linear fit function, calculate the COD concentration value of the test sample.
Preferably, the n modeling wavelength are chosen in the S5, refer to that absorbance change rate is not under isoconcentration gradient
Together, cause each wavelength only preferable in the linear relationship of a certain concentration range internal absorbance and concentration；At COD high concentration range,
Using the small wavelength of absorbance change under comparable sodium gradient as the modeling wavelength, at COD low strength range, using same
The big wavelength of absorbance change is as the modeling wavelength under isoconcentration gradient.
It is further preferred that the S8: including choosing the test sample according to n selected in the S5 modeling wavelength
Wavelength, by the wavelength of the test sample according to λ1To λnArrangement, from λ1Start, the test sample is in λ1At wavelength
Absorbance A1Whether λ is greater than1Maximum concentration absorbance A at wavelengthh1If being less than, the COD solution concentration of the test sample
Range is in λ1In the surveyed range of wavelength, if it is greater than or equal to Ah1, then the test sample is in λ2Absorbance A at wavelength2Whether
Greater than the λ2Maximum concentration absorbance A at wavelengthh2, and so on, until finding a certain selected wavelength Xm(1≤m≤n),
Absorbance A of the test sample at the wavelengthmLess than λ in the modeling wavelengthmMaximum concentration absorbance A at wavelengthhm,
That is λmWavelength is the optimal measurement wavelength of the solution.
Compared with prior art, the present invention have it is following the utility model has the advantages that
The present invention only needs unknown sample once to survey by the analysis processing of the full spectroscopic data of spectrum of COD sample solution
Amount saves testing time and cost without repeatedly replacing sample cell or adjusting the power and flicker frequency of light source.
It is measured with data analysing method of the present invention, is measured by experiment, survey concentration Duan Fan at each most optimum wavelengths
Linearly dependent coefficient between the COD concentration enclosed and absorbance is not less than 0.9964, and measurement error is 0.29% or so.As a result
It can be shown that the feasibility of full spectral measurement analysis method of the invention and the present invention can be high-precision simultaneously in guarantee, it is significant to expand
The measurement range of big COD concentration.
Detailed description of the invention
Upon reading the detailed description of non-limiting embodiments with reference to the following drawings, other feature of the invention,
Objects and advantages will become more apparent upon:
Fig. 1 is method flow diagram in one embodiment of the present invention；
Fig. 2 is the full spectrogram of absorbance of each concentration C OD solution in one embodiment of the present invention；
Fig. 3 is the function relation figure of one embodiment of the present invention medium wave strong point COD concentration and absorbance；
Fig. 4 is that wavelength COD concentration and extinction in its optimum measurement concentration range are modeled in one embodiment of the present invention
The linear relationship chart of degree.
Specific embodiment
The present invention is described in detail combined with specific embodiments below.Following embodiment will be helpful to the technology of this field
Personnel further understand the present invention, but the invention is not limited in any way.It should be pointed out that the ordinary skill of this field
For personnel, without departing from the inventive concept of the premise, various modifications and improvements can be made.These belong to the present invention
Protection scope.
As shown in Figure 1, the flow chart of the full spectral method of detection of wide-range high-precision of COD in water body concentration of the invention,
The description of particularly preferred embodiment of the invention is provided below in conjunction with the process.
In following embodiment, sample is the COD solution standard solution for the Potassium Hydrogen Phthalate prepared, and prepares 20
Standard solution with certain C OD concentration gradient is 0.1mg/L~900mg/L as modeling sample, COD concentration range, will be matched
20 modeling samples that system is completed are numbered, and number is respectively 1,2 ..., i ..., and 20.
In following embodiment, the absorption spectrum of each modeling sample is measured using spectral measurement device, device includes light source, standard
Lineal system, sample cell, convergence yoke and spectrometer.Light source issues light, the quartzy sample for being 10mm by colimated light system incidence light path
It in product pond, is emitted after being absorbed by water sample, is divided and detects by spectrometer after convergence yoke.
In following embodiment, light source can be used the wideband light sources such as xenon lamp, xenon flash lamp, deuterium lamp (wave band include 200nm extremely
600nm)；The concave mirror or collimating mirror for plating ultraviolet enhancing reflectance coating can be used in colimated light system；Plating can be used in convergence yoke
The concave mirror or convergent mirror of ultraviolet enhancing reflectance coating；Fiber spectrometer etc., which can be used, in spectrometer can be obtained full spectroscopic data
It is divided detection module.In other embodiments, the selection of above-mentioned light source, colimated light system, convergence yoke, spectrometer, is not limited to
It is above-mentioned several, other selections can be carried out according to application demand.
Based on above content, shown referring to Fig.1, specific step is as follows for embodiment:
Step 1: using experimental provision, measure 20 modeling samples, each modeling sample duplicate measurements 5 times obtains 20 groups
The full spectroscopic data of original spectrum of different COD concentration, every group of 5 full spectroscopic datas of original spectrum.
Step 2: average value of 5 original spectral datas at each wavelength in every group is acquired, as this group of COD concentration
Full spectroscopic data；
Step 3: according to formula, it is I that light intensity value of 20 groups of full spectroscopic datas at each wavelength, which is calculated,.
Wherein A is absorbance value, I0Luminous intensity when for COD concentration being zero.
According to lambert-Beer law, absorbance value of 20 groups of full spectroscopic datas at each wavelength is calculated.
A=KCL
Wherein K is absorption constant, and C is COD concentration value, and L is optical path length.
As shown in Figure 2, it can be seen that COD solution not only has absorption at 254nm, has suction at wavelength 220nm to 300nm sections
It receives, and wavelength is different, corresponding K value is different, causes same concentration different in the absorbance of each wavelength.
Step 4: according to all band absorbance value of 20 groups of various concentration COD standard solution, being fitted by least square method
The functional relation of absorbance and COD concentration at each wavelength is calculated, as shown in Figure 3.
Step 5: choosing 3 wavelength, respectively 224.3nm, 258.0nm and 297.3nm are as modeling wavelength, wherein each
Concentration section conduct of the linearly dependent coefficient greater than 0.99 is only chosen in modeling wavelength can linear concentration range.In 224.3nm wave
Strong point 0.1-10mg/L concentration range section linearly dependent coefficient is 0.9964；The 10-200mg/L concentration model at 258.0nm wavelength
Enclosing section linearly dependent coefficient is 0.9993；200-900mg/L concentration section linearly dependent coefficient is at 297.3nm wavelength
0.9964。
By 3 modeling wavelength of selection according to its it is corresponding can linear concentration range numbered from small to large as λ1, λ2, λ3,
Wherein to ensure λ1The maximum concentration surveyed at wavelength is equal to λ2The minimum concentration surveyed at wavelength, and so on.224.3nm
For λ1, the surveyed maximum concentration of 224.3nm wavelength is 10mg/L, equal to the surveyed minimum concentration of 258.0nm wavelength, 258.0nm wavelength
Surveyed maximum concentration is 200mg/L, equal to the surveyed minimum concentration of 297.3nm wavelength.Enable measurement range throughout from it is small to
Greatly.Hereby it is achieved that the expansion of measurement range, while ensure that the precision of measurement.
Step 6, calculate 3 of selection modeling wavelength correspondence can linear concentration range maximum concentration absorbance difference
For Ah1It is 0.134, Ah2It is 0.700, Ah3It is 0.297, minimum concentration absorbance is respectively Al1It is 0.009, Al2It is 0.050, Al3
It is 0.089, the foundation of selection range when as detection COD concentration.As shown in figure 4, calculating 3 wavelength by least square method
Respectively can absorbance and concentration in linear concentration range linear relationship, fitting function as the concentration section.
Step 7, configuration COD concentration is the standard solution of 46mg/L as test sample.Using the device of step 1 to test
Sample is detected, and the full spectroscopic data of test sample is measured, and according to 3 modeling wavelength selected in step 5, utilizes step
Formula in 3 calculates the absorbance that test sample models at wavelength at its 3, and the absorbance at 3 modeling wavelength is respectively A1
It is 0.344, A2It is 0.170, A3It is 0.021.
Step 8, according to modeling wavelength 224.3nm, 258.0nm and 297.3nm selected in step 5, by wavelength with λ1To λ3
Arrangement, from λ1Start, compares test specimen C OD solution in λ1Absorbance A at wavelength1With λ in modeling sample1At wavelength most
High concentration absorbance Ah1Size, work as A1Greater than Ah1When, continue to compare it in λ2Absorbance A at wavelength2Whether it is greater than and is built
λ in apperance product2Maximum concentration absorbance A at wavelengthh2, work as A2Less than Ah2.That is λ2Wavelength is the optimal measurement wavelength of the solution.
Step 9, gained λ when being modeled according to step 62Absorbance and concentration linear fit function y=at wavelength
293.41x-4.0127 obtaining test specimen C OD solution in λ by measurement2Absorbance value A at wavelength2, it can be calculated
COD concentration value is 45.867mg/L.
Using the above embodiment of the present invention, linear correlation degree is modeled up to 0.9964, measurement error 0.29%.
Experimental result sufficiently proves, compared to the conventional methods such as change optical path length, light source power and flicker frequency, this hair
The method of bright proposition only need to unknown sample carry out one-shot measurement, the full spectral information of the absorption spectrum of acquisition through this data method at
After reason, it can be significantly expanded its measurement range while guaranteeing high-acruracy survey COD concentration, save testing time and cost.
Specific embodiments of the present invention are described above.It is to be appreciated that the invention is not limited to above-mentioned
Particular implementation, those skilled in the art can make various deformations or amendments within the scope of the claims, this not shadow
Ring substantive content of the invention.
Claims (10)
1. a kind of wide-range high-precision spectral method of detection of COD in water body concentration, it is characterised in that: include:
The different COD concentration gradient solution of N group are configured as modeling sample, are measured with ultraviolet specrophotometer or spectral measurement device
Absorbance of each modeling sample in certain spectral region；
Go out the letter of modeling sample absorbance and COD concentration of standard solution at each wavelength by approximating method the Fitting Calculation
Number relationship；
Choose n wavelength therein as wavelength is modeled further according to the linearity of absorbance and concentration at each wavelength, wherein n >
2；The modeling wavelength is used as according to the COD concentration range that corresponding linearly dependent coefficient is chosen in required precision can linear concentration
Range；
Calculate the modeling wavelength can linear concentration range maximum concentration absorbance and minimum concentration absorbance, by quasi-
Conjunction method the Fitting Calculation go out the modeling wavelength respectively can absorbance and concentration in linear concentration range linear relationship；
Measure unknown concentration COD solution, comprising: the full spectroscopic data for measuring the unknown concentration COD solution, according to described
The n modeling wavelength selected in modeling sample, calculate absorbance of the unknown concentration COD solution at n wavelength；Selection institute
State the corresponding optimal measurement wavelength of unknown concentration COD solution concentration；Pass through the quasi- of concentration at the modeling wavelength and absorbance
Functional relation is closed, the COD concentration value of the unknown solution is calculated.
2. a kind of wide-range high-precision spectral method of detection of COD in water body concentration according to claim 1, feature exist
In: the modeling wavelength most preferably can linear COD concentration range, refer to: the modeling wavelength is chosen linearly dependent coefficient and is greater than
0.99 COD concentration range；
By each modeling wavelength according to it is corresponding most preferably can linear COD concentration range numbered from small to large as λ1, λ2…λn,
Number consecutively is λ to COD concentration range from small to large1, λ2... ..., λn, wherein to ensure λ1The maximum concentration etc. surveyed at wavelength
In λ2The minimum concentration surveyed at wavelength, and so on, enable measurement range throughout from small to large.
3. a kind of wide-range high-precision spectral method of detection of COD in water body concentration according to claim 2, feature exist
In: it is described to select the corresponding optimal measurement wavelength of the unknown concentration COD solution concentration, comprising: the unknown concentration COD is molten
The absorbance of liquid successively models wavelength X with described in the modeling sample1, λ2... ..., λnThe maximum concentration absorbance at place is successively
It is compared, when the absorbance of the unknown concentration COD solution is less than the maximum concentration absorbance modeled at wavelength, institute
State the optimal measurement wavelength that modeling wavelength is the solution.
4. a kind of wide-range high-precision spectral method of detection of COD in water body concentration according to claim 1, feature exist
In: the modeling wavelength refers to: at COD high concentration range, using the small wavelength of absorbance change under comparable sodium gradient,
At COD low strength range, using the big wavelength of absorbance change under comparable sodium gradient.
5. a kind of wide-range high-precision spectral method of detection of COD in water body concentration according to claim 1, feature exist
In: there is one or more of feature:
The absorption spectrum of the template sample is measured using UV, visible light spectrophotometric system；
The full spectroscopic data of absorbance of the modeling sample is measured using spectral measurement device, described device includes light source, collimation
System, sample cell, convergence yoke and spectrometer, wherein the light source issues light, passes through the incident sample of the colimated light system
Pond is emitted from the sample cell after being absorbed by the modeling sample, is received using after the convergence yoke by the spectrometer.
6. a kind of wide-range high-precision spectral method of detection of COD in water body concentration according to claim 1, feature exist
In: the different COD concentration gradient solution of the configuration N group are as modeling sample, comprising: preparing N number of has certain C OD concentration gradient
Standard solution as modeling sample, to each described modeling sample duplicate measurements M times, obtain the full light of the different COD concentration of N group
Modal data calculates M average values of the full spectroscopic data at each wavelength in every group, obtains the full light of the different COD concentration of N group
Modal data.
7. a kind of wide-range high-precision spectral method of detection of COD in water body concentration according to claim 6, feature exist
In: it is I that light intensity value of the modeling sample at each wavelength described in the different COD concentration of the N group, which is calculated, according to lambert-ratio
That law calculates absorbance value of the modeling sample at each wavelength described in the different COD concentration of N group.
8. a kind of wide-range high-precision spectral method of detection of COD in water body concentration according to claim 1-7,
It is characterized by: executing according to the following steps:
S1, it selects Potassium Hydrogen Phthalate to be configured to the different COD concentration gradient solution of N group as modeling sample, measures each described
The absorption spectrum of modeling sample obtains the full spectroscopic data of the different COD concentration of N group to described modeling sample duplicate measurements M times；
S2, in every group, M full average values of the spectroscopic data at each wavelength, the spectroscopic data as this group of COD concentration are calculated；
S3, absorbance value of the modeling sample at each wavelength described in N group various concentration is calculated；
S4, according to all band absorbance value of various concentration COD standard solution, each wavelength is gone out by least square method the Fitting Calculation
Locate the functional relation of absorbance and COD concentration；
S5, n wavelength is chosen, as modeling wavelength, absorbance and COD concentration relationship optimum linear section at each modeling wavelength
Corresponding COD concentration range be the modeling wave it is corresponding most preferably can linear COD concentration range, by each modeling wavelength
According to it is corresponding most preferably can linear COD concentration range to number from small to large be λ1, λ2…λn；
The modeling wavelength most preferably can linear COD concentration range refer to that the modeling wavelength chooses linearly dependent coefficient and is greater than 0.99
COD concentration range；
S6, it is each it is described modeling wavelength it is corresponding most preferably can linear concentration range threshold value be it is described most preferably can linear concentration
The minimum concentration and maximum concentration of range, the maximum concentration for surveying concentration range for calculating the n modeling wavelength of selection are inhaled
Luminosity and minimum concentration absorbance value, calculating the n modeling wavelength by least square method respectively can most preferably survey concentration
The linear relationship of absorbance and concentration in range；
S7, using unknown concentration COD solution as test sample, the full spectroscopic data of test sample is measured, according to the modeling sample
Selected n modeling wavelength of product, calculating absorbance of the test sample at the n modeling wavelength is A1,
A2... ... An；
S8, the corresponding optimal measurement wavelength of the selection test specimen C OD solution concentration, refer to the extinction of the test sample
Spend A1,A2... ..., AnSuccessively wavelength X is modeled with described in the modeling sample1, λ2... ..., λnThe maximum concentration absorbance at place
It is compared, when the absorbance A of the test samplemLess than the modeling wavelength XmWhen maximum concentration absorbance at wavelength, institute
State modeling sample λmWavelength is the optimal measurement wavelength of the solution.
S9, according to absorbance in S6 and concentration linear fit function, calculate the COD concentration value of the test sample.
9. a kind of wide-range high-precision spectral method of detection of COD in water body concentration according to claim 7, feature exist
In: in the S5, the n modeling wavelength are chosen, refer to that absorbance change rate is different under isoconcentration gradient, leads to each wavelength
It is only preferable in the linear relationship of a certain concentration range internal absorbance and concentration；At COD high concentration range, using comparable sodium ladder
The small wavelength of lower absorbance change is spent as the modeling wavelength, at COD low strength range, using inhaling under comparable sodium gradient
The big wavelength of light varience is as the modeling wavelength.
10. a kind of wide-range high-precision spectral method of detection of COD in water body concentration according to claim 7, feature
It is: the S8, comprising: the wavelength that the test sample is chosen according to n selected in the S5 modeling wavelength, by the survey
The wavelength of sample sheet is according to λ1To λnArrangement, from λ1Start, the test sample is in λ1Absorbance A at wavelength1It is whether big
In λ1Maximum concentration absorbance A at wavelengthh1If being less than, the COD solution concentration range of the test sample is in λ1Wavelength institute
It surveys in range, if it is greater than or equal to Ah1, then the test sample is in λ2Absorbance A at wavelength2Whether the λ is greater than2Wavelength
The maximum concentration absorbance A at placeh2, and so on, until finding a certain selected wavelength Xm, the test sample is at the wavelength
Absorbance AmLess than λ in the modeling wavelengthmMaximum concentration absorbance A at wavelengthhm, i.e. λmWavelength be the solution it is described most
Excellent measurement wavelength.
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| CN117554314A (en) * | 2024-01-11 | 2024-02-13 | 奥谱佳测(江苏)信息科技有限公司 | Method for eliminating COD concentration deviation based on TSS independent spectrum reconstruction |
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