CN102749318A - Device and method for detecting formaldehyde - Google Patents
Device and method for detecting formaldehyde Download PDFInfo
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- CN102749318A CN102749318A CN2012102514922A CN201210251492A CN102749318A CN 102749318 A CN102749318 A CN 102749318A CN 2012102514922 A CN2012102514922 A CN 2012102514922A CN 201210251492 A CN201210251492 A CN 201210251492A CN 102749318 A CN102749318 A CN 102749318A
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Abstract
An embodiment of the invention provides a device and a method for detecting formaldehyde. The device comprises a sampling system, a light source, a spectrometer and a control processor; the sampling system is used for collecting an air sample to be detected, the air sample is prepared into a formaldehyde solution sample, and the formaldehyde solution sample is excited by the light source to generate Raman scattering light; the light source is used for providing illumination for measuring a Raman spectrum of the formaldehyde solution sample; the spectrometer is used for splitting the Raman scattering mixed light to generate the Raman spectrum of the sample and converting light signals into computable electric signals; and the control processor is used for transmitting instructions for other portions of the device, controlling operations of the other portions of the device and processing the obtained Raman spectrum of the sample to measure the concentration of the formaldehyde in the air sample.
Description
Technical field
The present invention relates to field of spectral analysis technology, the apparatus and method that particularly a kind of formaldehyde detects.
Background technology
Formaldehyde (HCHO) is a kind of colourless at normal temperatures, and the gas of penetrating odor is arranged, soluble in water, pure and mild ether.Formaldehyde all has strong harm, Long contact time can cause the tissue distortion to people's eyes, respiratory system, nervous system etc. and causes canceration, so it is a kind of potential dangerous carcinogenic substance and important environmental contaminants, and is seriously harmful to human body.
A lot of art works all contain formaldehyde like scale board, core-board, polyfoam and paint and some chemical fibre carpet, coating.So the room of just having fitted up generally all can exist formaldehyde to exceed standard, this also is the topic of being discussed warmly by the people when next; Also can contain the formaldehyde composition in some cosmetics in addition.Owing to being in the too high indoor case that causes pathology of formaldehyde for a long time, report is also arranged in recent years repeatly, especially for the more weak children of immunity, influence even more serious.In a word in daily life, the control to content of formaldehyde in the environment is to guarantee one of key of healthy living.This also just make people in daily life or commercial production in, need carry out real-time detection to airborne content of formaldehyde.
The GB detection method of formaldehyde mainly contains chemical method and instrumental method two big classes at present.Chemical method mainly contains phenol reagent process, acetylacetone method, variable color acid system, hydrochloric para-rosaniline method etc.Instrumental method mainly comprises vapor-phase chromatography, the chromatography of ions, oscillographic polarography determination method etc.These methods have advantage separately, all satisfy degree of certainty height, the requirement that measurement range is wide generally.But these methods all are to belong to offline inspection, analyze after just the laboratory being gone back in the gaseous sample collection; So carry out according to the method described above that sense cycle is long, cost is high, complex steps, can not directly carry out at scene to be detected, can't reflect room air formaldehyde pollution degree in real time and satisfy the monitoring needs of on-the-spot large quantities of measuring points.
Also has a kind of method of utilizing the spectral detection system to detect content of formaldehyde in the prior art.This system is based on phenol reagent and divides the luminosity principle, obtains the spectrogram of formaldehyde analytic liquid, is reference with the absorption maximum intensity of canonical reference liquid, tries to achieve concentration of formaldehyde.This to utilize the advantage of the method for spectral detection be that efficient is higher, can realize this requirement of fast detecting.But traditional spectral analysis technique needs chemical reagent to participate in detecting after the corresponding reaction again, is to detect bringing back the laboratory after the sample collection equally.And chemical reagent itself is harmful, and this method to the conforming requirement of surrounding environment and measuring condition than higher, therefore using in actual detection has certain limitation.Therefore the exploitation of formaldehyde pick-up unit fast and accurately is very important.
Summary of the invention
In view of this, the object of the present invention is to provide a kind of formaldehyde pick-up unit and method, said apparatus and method realize online real-time on-site fast detecting content of formaldehyde based on the Raman spectrum principle.
For realizing above-mentioned purpose, the present invention has following technical scheme:
A kind of formaldehyde pick-up unit, said device comprises:
Sampling system is used to gather air sample to be detected, and air sample is processed the formalin sample, and makes the formalin sample under the exciting of excitation source, produces Raman diffused light;
Light source, the raman spectroscopy measurement that is used to the formalin sample provides illumination, excites it that Raman scattering takes place;
Spectrometer is used to gather Raman diffused light, utilizes said Raman scattering photogenerated sample Raman spectrum, and its light signal is changed into electric signal;
Processor controls is used for other parts of said device are sent instruction, controls the workflow of whole device, and receives the sample Raman spectrum and analyze, and records the concentration of formaldehyde in the air sample.
Said sampling system specifically comprises:
Air pump is used to extract air sample to be measured;
Sample cell is used to take up deionized water, and the formaldehyde in the air sample is dissolved in the deionized water, processes the formalin sample;
Sampling probe is used to conduct the light that light source produces, and makes light drop on the formalin sample surface and produces Raman diffused light; And with conducting to spectrometer after the Raman diffused light collection.
Said device also comprises:
Output Display Unit is used for obtaining from processor controls the measurement result and the demonstration of concentration of formaldehyde.
Said device also comprises:
Supply unit is used to other parts of said device electric energy is provided.
A kind of concentration of formaldehyde detection method said method comprising the steps of:
Gather air sample to be detected, air sample is processed the formalin sample;
Utilize light source PARA FORMALDEHYDE PRILLS(91,95) solution sample to excite, produce Raman diffused light;
Gather Raman diffused light, utilize said Raman scattering photogenerated sample Raman spectrum;
Raman spectrum is analyzed, recorded the concentration of formaldehyde in the air sample.
Saidly air sample processed formalin be specially:
Air pump extracts the air in certain amount sample, through corresponding conduit air sample is contacted with deionized water, and the formaldehyde in the air sample is dissolved in the deionized water fully, obtains the formalin sample.
The said sampling system acquisition formalin Raman diffused light that utilizes is specially:
The illumination line focus lens that said continuous wave laser sends converge to the surface of formalin sample, and the Raman scattering light intensity that makes the formalin sample be excited to produce is maximum.Thereby improve the signal to noise ratio (S/N ratio) of Raman spectrum.
Said method also comprises:
The concentration of formaldehyde that utilizes Output Display Unit to demonstrate to record.
A kind of method through Raman spectrum quantitative test calculating concentration of formaldehyde said method comprising the steps of:
Standard formalin to different concentration known is carried out the Raman spectrum collection, obtains corresponding Raman spectrum;
Utilize the concentration Raman spectrum corresponding of said different standard formalin to set up calibration model with it;
Adopt method, instrument and the parameter setting identical to carry out the Raman spectrum collection to the formalin sample that utilizes air sample to process, obtain the sample to be tested Raman spectrum with standard formalin;
With sample to be tested Raman spectrum substitution calibration model, calculate the concentration of formaldehyde of formalin sample.
Saidly utilize the known formalin concentration of the said difference standard Raman spectrum corresponding to set up calibration model to be specially with it:
The Raman spectrum of each master sample is carried out noise reduction process, and utilize independent principal component analytical method to calculate the weight matrix of the pure raman spectral signal that does not carry background and other interference of the master sample behind the noise reduction;
Utilize known formalin concentration and said weight matrix to set up calibration model.
Can know through above technical scheme; The beneficial effect that the present invention exists is; The mode that this Design of device is especially combined by air pump and sampling system is applied to the online detection of content of formaldehyde in the air with the Raman spectrum quantitative analysis tech, and gasmetry is converted into liquid measure; Alleviated influence greatly, increased the service life detector.In addition,, need not, can realize the airborne content of formaldehyde of quick test of real-time on-site by chemical reagent based on the Raman diffused light of Raman spectrum analysis principle analysis formalin.And the present invention adopts independent PCA in the middle of spectral analysis, got rid of the interference of background context and other information, has avoided interference and the limitation of environment to measurement result, makes measurement result more accurate.
Description of drawings
In order to be illustrated more clearly in the embodiment of the invention or technical scheme of the prior art; To do to introduce simply to the accompanying drawing of required use in embodiment or the description of the Prior Art below; Obviously, the accompanying drawing in describing below is some embodiments of the present invention, for those of ordinary skills; Under the prerequisite of not paying creative work, can also obtain other accompanying drawing according to these accompanying drawings.
Fig. 1 is the said formaldehyde pick-up unit of an embodiment of the invention structural representation;
Fig. 2 is the said formaldehyde pick-up unit of an another embodiment of the present invention structural representation;
Fig. 3 is the said formaldehyde detection method of an embodiment of the invention process flow diagram;
Fig. 4 is the said formaldehyde detection method of an another embodiment of the present invention process flow diagram;
Fig. 5 is the said method flow diagram that calculates concentration of formaldehyde through Raman spectrum analysis of the embodiment of the invention;
Fig. 6 is the said method flow diagram that calculates concentration of formaldehyde through Raman spectrum analysis of another embodiment of the present invention.
Embodiment
For the purpose, technical scheme and the advantage that make the embodiment of the invention clearer; To combine the accompanying drawing in the embodiment of the invention below; Technical scheme in the embodiment of the invention is carried out clear, intactly description; Obviously, described embodiment is the present invention's part embodiment, rather than whole embodiment.Based on the embodiment among the present invention, those of ordinary skills are not making the every other embodiment that is obtained under the creative work prerequisite, all belong to the scope of the present invention's protection.
The definition of Raman scattering (Raman scattering) is, light during through medium because Ramam effect is claimed in the scattering that the frequency that incident light and molecular motion interaction cause changes again.The characteristics of molecule self are only depended in the variation displacement of this frequency, and certain confirms that the light scattering intensity of frequency displacement place is directly proportional with corresponding molecular conecentration.The Raman spectrum analysis method is based on above-mentioned Ramam effect, scattering spectrum analyze different with the incident light frequency is obtained molecular vibration, rotation aspect information, and can be applied to the quantitative test that some infrared absorption is not a material clearly.The present invention provides fundamental basis according to the analysis of Raman scattering and Raman spectrum just, obtains concentration of formaldehyde thereby PARA FORMALDEHYDE PRILLS(91,95) solution sample carries out spectral analysis.
With reference to shown in Figure 1, be the specific embodiment of formaldehyde pick-up unit according to the invention.In the present embodiment, said device comprises:
Sampling system is used to gather air sample to be detected, and air sample is processed the formalin sample, and makes the formalin sample receive exciting of light source, produces Raman diffused light;
Light source, the raman spectroscopy measurement that is used to the formalin sample provides exciting light to shine;
Spectrometer with the Raman diffused light beam split and the opto-electronic conversion that collect, obtains the Raman spectrum of sample;
Processor controls is used for other parts of said device are sent instruction, the work of other parts of control device, and the sample Raman spectrum that receives analyzed, calculate the concentration of formaldehyde in the air sample.
Present embodiment is the basic embodiment of formaldehyde pick-up unit according to the invention.The beneficial effect that device exists described in the present embodiment is: utilize Raman scattering effect to carry out quantitative spectrochemical analysis in the present embodiment; Need not by various virulent chemical reagent; Also need not to carry out complicated chemical reaction; Said collection air sample all can be accomplished by real-time on-site with the step of making the formalin sample, no longer receives the limitation of environment, has realized that online concentration of formaldehyde detects; So the said device of present embodiment promptly possesses spectral detection advantage efficiently, having solved traditional spectral method of detection again can only offline inspection, and poisons serious technical disadvantages.
With reference to shown in Figure 2, be another specific embodiment of formaldehyde pick-up unit according to the invention.In the middle of the present embodiment, said device specifically comprises:
Sampling system is used to gather air sample to be detected, and air sample is processed the formalin sample, and makes the formalin sample accept raman spectroscopy measurement, produces Raman diffused light;
Sampling system described in the present embodiment specifically comprises air pump, conduit, sample cell and sampling probe four parts;
Air pump is used to gather air sample; Just utilize air pump to extract in the space to be measured air in certain amount as sample air.The air pump of choosing in the present embodiment is specially diaphragm type air pump DA60DC-TH, and the flow of air is 12L/min.
Conduit, the air sample that air pump is extracted is transported to sample cell.
Sample cell is used to take up deionized water, and the formaldehyde in the air sample is dissolved in the deionized water, processes the formalin sample;
The air sample that in the present embodiment air pump is extracted contacts with deionized water in the sample cell through conduit, and is soluble in water owing to formaldehyde, so the formaldehyde in the air sample can be dissolved in the deionized water automatically, processes the formalin sample thus.Select for use the purpose of deionized water to be to make formaldehyde dissolving more completely more fast in the present embodiment.
Sampling probe is used to conduct the illumination that light source produces, and makes illumination drop on the formalin sample surface and produces Raman diffused light; And Raman diffused light conducted to spectrometer;
Sampling probe connects light source and spectrometer through optical fiber in the present embodiment.Sampling probe makes light directly drop on the top layer of formalin sample from the light that light source conduction carrying out raman spectroscopy measurement needs.In the present embodiment in order to make the concentration of energy of light; Front end at sampling probe has been installed condenser lens; And the distance of adjustment sampling probe and solution surface, the focus of light is just dropped on the surface of formalin sample, strengthen Raman scattering intensity thus; Increase the signal to noise ratio (S/N ratio) of spectrum, be convenient to follow-up analysis and calculating.What the formalin sample received light source excites the generation Raman diffused light, and sampling probe is collected this Raman diffused light and through optical fiber it conducted on the spectrometer.
Light source, the generation Raman scattering effect that is used to the formalin sample provides excitaton source; For continuous coverage, said light source has specifically been chosen continuous wave laser in the present embodiment, and the centre wavelength of laser instrument is chosen to be 785nm.Choosing of laser center wavelength need be complementary with the model and the function of spectrometer, so under other concrete environment, also can change the centre wavelength of laser as required.Generally need possess higher energy and good unicity but carry out the required light source of raman spectroscopy measurement, so general first-selection is a laser.
Spectrometer is used to gather Raman diffused light, utilizes said Raman scattering photogenerated sample Raman spectrum; The principle of work of spectrometer can be concise and to the point be summarised as; The Raman diffused light that collects is carried out light-splitting processing; And light signal changed into electric signal, again through follow-up A/D conversion circuit and signal amplification circuit, obtain being output to the high-quality digital signal of follow-up system.Certainly, spectrometer described in the present embodiment belongs to conventional instrument and equipment of present stage, gives unnecessary details so no longer make for its process of making the sample Raman spectrum.The spectrometer model of selecting for use in the present embodiment is the QE65000 spectrometer of marine optics, also can select other can carry out the portable spectrometer of communication with microprocessor in the practical application.
Processor controls is used for other parts of said device are sent instruction, the workflow of other parts of control device, and receive the sample Raman spectrum and analyze, record the concentration of formaldehyde in the air sample.
In the present embodiment, processor controls plays the effect of hinge in single unit system.Said processor controls plays control action to whole testing process, and can carry out data processing.The control action aspect of processor controls comprises the instruction for duty between each each building block of device, each other the control and management of the signal of communication and measurement flow process; Also be provided with IO interface on the processor controls and be connected, to realize receiving functions such as user's steering order, output demonstration measurement result with peripheral input-output device.Aspect data processing, the sample Raman spectrum that processor controls receiving spectrum appearance generates carries out pre-service and concentration prediction to it, finally obtains concentration of formaldehyde to be measured.Comprise dsp chip or CPU in the said as required processor controls.
Output Display Unit is used for obtaining from processor controls the measurement result and the demonstration of concentration of formaldehyde; Increased Output Display Unit in the present embodiment, be used for reflecting the net result that processor controls detects more intuitively, said Output Display Unit is connected with processor controls, can obtain testing result and demonstration that processor controls is calculated.
Supply unit is used to other parts of said device electric energy is provided; Supply unit can convert civilian 220V alternating current to direct current of voltage regulation that the device each several part can directly use; Perhaps said supply unit also can be the accumulator that satisfies the relevant voltage current class.
Present embodiment is a preferred embodiment of said formaldehyde pick-up unit.Provide more concrete description and explanation for each several part in the present embodiment, and increased a part of preferred technical characterictic.Present embodiment is on embodiment illustrated in fig. 1, and the beneficial effect that further possesses is, the design through the refinement sampling probe in the present embodiment; The Raman scattering light intensity is increased; Spectral signal-noise ratio improves, thereby the Raman spectrum quality that obtains is higher, so the result of its detection is also inevitable more accurate; Demonstrate testing result intuitively through Output Display Unit in the present embodiment, can improve user's experience impression.Technical scheme is more complete in the present embodiment on the whole, more perfect function.
With reference to shown in Figure 3, be the specific embodiment of formaldehyde detection method according to the invention.Said method comprising the steps of:
Present embodiment is a basic embodiment of said method, the device embodiment that its substantive technical characterictic is corresponding shown in Figure 1.So the beneficial effect that method described in the present embodiment exists is: utilize Raman scattering effect to carry out substance quantitative analysis in the present embodiment; Need not by various virulent chemical reagent; Also need not to carry out complicated chemical reaction; Said collection air sample all can be accomplished by real-time on-site with the step of making the formalin sample, no longer receives the limitation of environment, has realized that online concentration of formaldehyde detects; So the said method of present embodiment promptly possesses spectral detection advantage efficiently, having solved traditional spectral method of detection again can only offline inspection, and poisons serious technical disadvantages.
With reference to shown in Figure 4, be another specific embodiment of the method for the invention.Method may further comprise the steps described in the present embodiment:
Step 401, power-on, booster air pump utilizes air pump to extract in the space to be measured air in certain amount as air sample;
Step 402, in sample cell, inject deionized water, air sample is contacted with deionized water, the formaldehyde in the air sample is dissolved in the deionized water fully, process the formalin sample; Select for use the purpose of deionized water to be to make formaldehyde dissolving more completely more fast in the present embodiment.
Step 403, light source send continuous laser,,, drop on the surface of formalin sample after the condenser lens through the sampling probe front end focuses on to sampling probe through fiber optic conduction, excite the formalin sample to produce Raman diffused light;
The Raman diffused light that step 404, sampling probe collection generate, through fiber optic conduction to spectrometer;
Step 405, spectrometer carry out light-splitting processing with the Raman diffused light that collects, and light signal is changed into electric signal, again through follow-up A/D conversion circuit and signal amplification circuit, generate the sample Raman spectrum;
Step 406, spectrometer are sent to processor controls with the sample Raman spectrum, by processor controls Raman spectrum are carried out pre-service and spectral analysis, calculate the concentration of formaldehyde in the sample air.
Need to prove that processor controls is the concentration of formaldehyde of formalin sample through the concentration of formaldehyde that spectral analysis directly obtained in the present embodiment, final also need the concentration of formaldehyde of formalin sample the conversion becomes the concentration of formaldehyde in the sample air; Utilize the concentration of formaldehyde of formalin sample can calculate the content of formaldehyde in the formalin sample, the amount of this content of formaldehyde and sample air is being asked ratio, can draw the concentration of formaldehyde of sample air.The amount of said content of formaldehyde, sample air is in volume or the molar weight that can choose on the physical unit under quality, the normal temperature and pressure; The ratio of the two also can be mass ratio, volume ratio or mol ratio.
The said method of present embodiment is corresponding with device embodiment shown in Figure 2 in fact.And present embodiment has provided more concrete description and explanation on the basis of method embodiment shown in Figure 3, and has increased a part of preferred technical characterictic.So present embodiment is except possessing central beneficial effect embodiment illustrated in fig. 3; Its beneficial effect that further obtains is: the design through the refinement sampling probe in the present embodiment; The Raman scattering light intensity is increased, and spectral signal-noise ratio improves, thereby the Raman spectrum quality that obtains is higher; Demonstrate testing result intuitively through Output Display Unit in the present embodiment, can improve user's experience impression.Technical scheme is more complete in the present embodiment on the whole, more perfect function.
In the middle of 4 embodiment of Fig. 1-shown in Figure 4, all be to utilize processor controls that the sample Raman spectrum is carried out spectral analysis, and obtain the numerical value of concentration of formaldehyde.When carrying out said spectral analysis, need set up calibration model in advance among the present invention, and calibration model is stored in the processor controls, just can the sample to be tested Raman spectrum be brought in the middle of the calibration model then.So with reference to shown in Figure 5, the present invention discloses a kind of method through Raman spectrum analysis calculating concentration of formaldehyde especially, below is the specific embodiment of this method:
In the present embodiment, the main thought of said method can be interpreted as: the formalin of the multiple variable concentrations of preparation is as standard formalin earlier, and the concentration of standard formalin is known.Formalin according to same light source activation variable concentrations; The Raman spectrum that the obtains ultimate principle that light intensity is directly proportional with concentration of formaldehyde at the characteristic peak place; Earlier the standard formalin of variable concentrations is carried out raman spectroscopy measurement, obtain the standard Raman spectrum under the variable concentrations.This also just can confirm the spectral signature under some concentration of formalin, utilizes these concentration to set up calibration model with the relation between the corresponding spectral signature (peak intensity or peak area) again.For the formalin of unknown concentration, only need can calculate the concentration of this formalin with in its spectrum substitution calibration model.
Method may further comprise the steps described in the present embodiment:
In the present embodiment, make bright specifically as follows for the method for setting up calibration model:
As far as the Raman spectrum analysis of routine, described modeling process can be used common chemical metrology method and realize.Said conventional chemical metrology method is the known method in this area, its principle is not carried out unnecessary description at this.The Raman spectrum quantitative analysis method relatively is suitable for the quantitative test of the WS, because it can avoid the influence of moisture.Traditional Raman spectrum quantitative analysis method utilizes position, the peak at Raman scattering peak concentration parameter strong or that peak area combines to be correlated with to set up calibration model; But than the influence that is easier to receive measuring condition and environment, so that its defective is the degree of accuracy of model is not ideal enough.If want to improve degree of accuracy, the background deduction of sample cell will be by the improvement on the entity apparatus and remove background in necessary part, and this design for device and instrument has proposed very high requirement.
Introduce independent PCA in the present embodiment again on this basis and carried out spectral analysis and modeling.Utilize the step of independent major component modeling following:
Step 521, the standard Raman spectrum is carried out denoising; Denoising described in the present embodiment adopts the window smoothing method to carry out;
Step 522, the standard Raman spectrum after utilizing independent PCA to denoising are handled, and according to the characteristic scattering wave long of ethanol, remove the background that the sample cell scattering causes, and obtain the weight matrix of the pure spectrum information of formaldehyde molecule scattering;
Said independent PCA is the method that a kind of blind source signal of the eighties of last century proposition nineties separates, and has obtained good effect at aspects such as various feature extractions, medical science identifications afterwards.Present embodiment is applied in it in the middle of quantitative test of Raman spectrum, to the substantial change that do not have of this algorithm itself.Only make an explanation in the accessible effect of the present invention for independent PCA; Raman spectrum after the denoising is carried out independent principal component analysis (PCA); Can obtain a pure spectrum matrix and a weight matrix relevant through corresponding calculated with material concentration; The prior imformation of the Raman scattering characteristic through formaldehyde; Only choose the corresponding weight matrix of the pure spectrum of formaldehyde scattering, so in fact all interference that bring of background and noise all can be included in the middle of the not selected part, so utilize weight matrix and concentration to set up the influence that model can be eliminated interfere information at last.This shows that this algorithm application can be got rid of measurement environment and measure the influence of background for measurement result in the present embodiment.Utilize said independent major component modeling no longer need remove the background of sample cell, realized under the situation that does not change instrument and device, improve the degree of accuracy of model.
Step 523, utilize the said weight matrix standard formalin concentration corresponding to set up calibration model with it; Said calibration model belongs to multiple linear regression model;
Saidly set up the mathematical method that calibration model can adopt and mainly contain: multiple linear regression analysis method (Multiple Linear Regression; MLR), partial least-squares regression method (Partial Least Square; PLS) or the least square method supporting vector machine Return Law (Least Square Support Vector Regression, SVR).Adopted partial least-squares regression method in the present embodiment; Said partial least-squares regression method is a modal modeling method in the Chemical Measurement field; Be conventionally known to one of skill in the art, only provide simple explanation at this: PLS is the mode through the extraction latent variable, in the time of dimensionality reduction; With simulating straight line between latent variable and the aimed concn, make it minimum in the quadratic sum of the distance on the coordinate system and between the given data.The standard formalin concentration that said weight matrix is corresponding with it is through the mode modeling of PLS, and the calibration model that draws belongs to multiple linear regression model.This calibration model has been got rid of the influence and the interference of contextual factor, and its degree of accuracy is significantly improved with respect to traditional mathematical model degree of accuracy of utilizing the Raman quantitative analysis method to set up.
In following examples, complete provided above spectral analysis process, with reference to shown in Figure 6:
The denoising method of step 606, corresponding standard Raman spectrum, selected identical denoising parameter is carried out denoising to the sample Raman spectrum;
In the present embodiment, the denoising process need of sample Raman spectrum and standard Raman spectrum is consistent on effect, thus method that relates in the denoising process and parameter the two must be identical.
The independent principal component analytical method of step 607, corresponding standard Raman spectrum obtains correlation parameter, and the sample Raman spectrum after adopting identical parameter to denoising carries out independent principal component analysis (PCA), obtains the corresponding weight matrix of sample to be tested;
The same, the independent principal component analysis (PCA) of sample Raman spectrum also need keep consistency with the standard Raman spectrum in the present embodiment, thus the parameter that relates in this process the two need choose identical value equally.
Said calibration model has promptly reflected the relation between weight matrix and the concentration, so this model of weight matrix substitution that unknown sample is corresponding, the result who draws has promptly reflected its concentration.
Utilize the concentration of formaldehyde of formalin sample can calculate the content of formaldehyde in the formalin sample, then the amount of content of formaldehyde and sample air is asked ratio, can draw the concentration of formaldehyde of sample air, this computation process belongs to conventional mathematical algorithm.The amount of said content of formaldehyde, sample air is in volume or the molar weight that can choose on the physical unit under quality, the normal temperature and pressure; The ratio of the two also can be mass ratio, volume ratio or mol ratio.
Fig. 5 and two embodiment shown in Figure 6, the method that obtains concentration of formaldehyde is analyzed and detected to detailed disclosing to the sample air Raman spectrum.The beneficial effect that above-mentioned two embodiment exist is, concrete realization for the detection of concentration of formaldehyde.And in the modeling process of spectral analysis, can adopt conventional Raman quantitative analysis method or independent PCA.Adopted independent PCA in embodiment illustrated in fig. 6, its beneficial effect is to have got rid of the interference of background for calibration model, has improved the degree of accuracy of calibration model.
The above only is a preferred implementation of the present invention; Should be pointed out that for those skilled in the art, under the prerequisite that does not break away from the principle of the invention; Can also make some improvement and retouching, these improvement and retouching also should be regarded as protection scope of the present invention.
Claims (10)
1. a formaldehyde pick-up unit is characterized in that, said device comprises:
Sampling system is used to gather air sample to be detected, and air sample is processed the formalin sample, and makes the formalin sample under the exciting of excitation source, produces Raman diffused light;
Light source, the raman spectroscopy measurement that is used to the formalin sample provides illumination, excites it that Raman scattering takes place;
Spectrometer is used to gather Raman diffused light, utilizes said Raman scattering photogenerated sample Raman spectrum, and its light signal is changed into electric signal;
Processor controls is used for other parts of said device are sent instruction, controls the workflow of whole device, and receives the sample Raman spectrum and analyze, and records the concentration of formaldehyde in the air sample.
2. according to the said device of claim 1, it is characterized in that said sampling system specifically comprises:
Air pump is used to extract air sample to be measured;
Sample cell is used to take up deionized water, and the formaldehyde in the air sample is dissolved in the deionized water, processes the formalin sample;
Sampling probe is used to conduct the light that light source produces, and makes light drop on the formalin sample surface and produces Raman diffused light; And with conducting to spectrometer after the Raman diffused light collection.
3. according to claim 1 or 2 said devices, it is characterized in that said device also comprises:
Output Display Unit is used for obtaining from processor controls the measurement result and the demonstration of concentration of formaldehyde.
4. according to claim 1 or 2 said devices, it is characterized in that said device also comprises:
Supply unit is used to other parts of said device electric energy is provided.
5. a concentration of formaldehyde detection method is characterized in that, said method comprising the steps of:
Gather air sample to be detected, air sample is processed the formalin sample;
Utilize light source PARA FORMALDEHYDE PRILLS(91,95) solution sample to excite, produce Raman diffused light;
Gather Raman diffused light, utilize said Raman scattering photogenerated sample Raman spectrum;
Raman spectrum is analyzed, recorded the concentration of formaldehyde in the air sample.
6. according to the said method of claim 5, it is characterized in that, saidly air sample is processed formalin be specially:
Air pump extracts the air in certain amount sample, through corresponding conduit air sample is contacted with deionized water, and the formaldehyde in the air sample is dissolved in the deionized water fully, obtains the formalin sample.
7. according to the said method of claim 5, it is characterized in that the said sampling system acquisition formalin Raman diffused light that utilizes is specially:
The illumination line focus lens that said continuous wave laser sends converge to the surface of formalin sample, and the Raman scattering light intensity that makes the formalin sample be excited to produce is maximum.Thereby improve the signal to noise ratio (S/N ratio) of Raman spectrum.
8. according to any said method of claim 5-7, it is characterized in that said method also comprises:
The concentration of formaldehyde that utilizes Output Display Unit to demonstrate to record.
9. the method through Raman spectrum quantitative test calculating concentration of formaldehyde is characterized in that, said method comprising the steps of:
Standard formalin to different concentration known is carried out the Raman spectrum collection, obtains corresponding Raman spectrum;
Utilize the concentration Raman spectrum corresponding of said different standard formalin to set up calibration model with it;
Adopt method, instrument and the parameter setting identical to carry out the Raman spectrum collection to the formalin sample that utilizes air sample to process, obtain the sample to be tested Raman spectrum with standard formalin;
With sample to be tested Raman spectrum substitution calibration model, calculate the concentration of formaldehyde of formalin sample.
10. according to the said method of claim 9, it is characterized in that, saidly utilize the known formalin concentration of the said difference standard Raman spectrum corresponding to set up calibration model to be specially with it:
The Raman spectrum of each master sample is carried out noise reduction process, and utilize independent principal component analytical method to calculate the weight matrix of the pure raman spectral signal that does not carry background and other interference of the master sample behind the noise reduction;
Utilize known formalin concentration and said weight matrix to set up calibration model.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103396458A (en) * | 2013-08-12 | 2013-11-20 | 宁波大学 | Compound with electrochemical response to formaldehyde and preparation method thereof |
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