Qualitative Analysis And Quantitative Analysis Of Multicomponent Mixed System Based On Subspace Angle And Angle Measurement Method

Chemometrics methods could extract “interesting informations” in datas of modernanalytical instruments through analyzing measured datas and farthest obtaining chemicaland related informations to solve some problems that traditional methods can not deal with.A component or multiple components of mixed system under unknown interference can beanalyzed qualitatively and analzed quantificationally when modern analytical instrumentsare combined with chemometrics to replace “mathematical separation” with “chemicalseparation” in “interesting informations” of mixed system.1. Basic principle, calculation method of subspace angle, qualitative analysis steps ofapplying “the mixed spectral pattern recognition of judging the subspace coincidence” toqualitiative analysis of mixed system, and feasibility, basic principle, quantitative analysissteps of “multivariable analysis regression method based on angle measurement” areintroduced in detail.Multicomponent mixed system are analyzed qualitatively and analyzedquantificationally through Raman fiber spectrometer combining with above two methods.In this study, the main research contents are presented as follows:2.“The mixed spectral pattern recognition of judging the subspace coincidence” wascompiled and applied in the qualitative detection of eleven mixed alcohol solution ofdifferent proportion. And compared with the results of characteristic peak intercomparisonmethod and “similarity” judging method, the method was successfully complete thequalitative recognition of all eleven mixed alcohol solution of different proportion. Thedetection rate of the method is100%. Also the method have lots of merits such as accurate,simple, rapid, sensitive and time saving, which is suitable for qualitative detection ofmulitcomponent mixed system such as not typical peak of peak shifting and peak overlap.3.“The multivariable analysis method based on angle measurement” was applying in.detecting mixed alcohol solution systems of three and five kinds for quantitative analysisunder fixed and no fixed distance, after that, and compared with the result of the Ramanspectra of three and five kinds mixed alcohol using PLS directly. The results show thatPLS could not express the accurate quantitative relationship under no fixed distancemeasurement, but the analysis method, which based on angle measurement, couldobviously reduce demand for environment in process, could accomplish quantitativeanalysis under situation with unstable signal intensity, could satisfy the requirement ofRaman spectra in noninvasive quantitative analysis.4. How to detect the alcohol content of fermentation liquid simply, efficiently,accurately is a key problem.“The multivariable analysis method based on anglemeasurement” and PLS was used to detect the alcohol degree of cassava fermentationliquid. When compared with results of traditional “distiller alcohol densimeter” method,the residual error of results of PLS and “distiller alcohol densimeter” method is -3.84%-1.63%, and that of angle measurement and “distiller alcohol densimeter” methodis-0.90%-0.74%. Above results infer that predictions of angle measurement is accurate,but that of PLS is not accurate. The angle measurement method could complete unknowncomponent analysis in multiple components of mixed system under the different factorsinfluence such as light quantity, light path, refractive index and background absorbtion.This method could complete quantitative analysis only to detect the spectral informationsof mixed components system and the spectral information of under test of pure componentwithout knowing kind and amount of system. The advantages of this method are simple,efficient.