The Application Researches Of Tchebichef Moment Methods In The Analysis Of Chemical Spectra

Along with the rapid development of modern analytical methods and related instrumentations,it allows researchers to obtain the rich information of a large number of analytical samples in a short time.However,it is still difficult to directly and accurately analyze multi-target components in the complex systems by conventional analytical techniques,and it is difficult to obtain satisfactory results.Therefore,how to extract useful target information from the large amount of data obtained from these analytical instruments has become an urgent problem for researchers.The development of chemometrics has provided a convenience in the study of complex system.Image moments have many advantages,such as the image description capability,multi-resolution ability and invariance property in translation,scaling and rotation,owning to these advantages,the image moments can be applied to quantitative determination of multiple target compounds in complex samples on the basis of 3D chemical spectra,even in the presence of multiple interferences.In addition,we first proposed the curve moment method to meet the needs for the analysis of conventional 2D chemical spectra.The curve moment was extended from the image moment and its properties are the same as those of the image moment.We refer to the image moments and curve moments collectively as chemical moments.The application of Tchebichef moment methods based on the conventional chemical spectra(3D/2D)was studied,and the main researches of this dissertation are as follows:Chapter 1 The introduction mainly summarizes the development of chemometrics and its application in the analysis of conventional spectra(3D spectra,2D spectra),the development of moment methods and its application in analytical chemistry.At last,the research work of this dissertation introduced briefly.Chapter 2 The quantitative analysis of curcuminoids in turmeric and curry based on excitation-emission(EEM)fluorescence spectroscopy with Tchebichef image momentsCurcuminoids,the main active components of turmeric and curry,have exhibited extensive therapeutic benefits.The similar chemical structures of curcuminoids result in the overlapped peaks in their spectral domains,apart from this,uncalibrated spectral interferences also pose a practical problem and complex pretreatments are necessary.In the presented work,a Tchebichef image moment approach was proposed for the simultaneous quantitative analysis of three major curcuminoids(curcumin,DMC and BDMC)in turmeric and curry based on the EEM 3D spectra.Tchebichef image moments was directly calculated on the grayscale images of their original EEM 3D spectra,and the linear quantitative models for the three curcuminoids were established by stepwise regression,respectively.The performance of the obtained quantitative linear models was evaluated by means of the statistical parameters in terms of correlation coefficient and root mean squared error.The effectiveness of the approach was evaluated using intra and inter-day precision and recovery.In comparison to the N-way Partial Least Squares(N-PLS),the TM-Stepwise approach presents the better performance.This study indicates that the proposed approach can reduce the analysis steps and analyses can be much simpler,which is expected to be a potential tool to rapidly quantify multi-target components in mixture without complex pretreatments.Chapter 3 Tchebichef image moment approach to the prediction of protein secondary structures based on circular dichroismCircular dichroism(CD)spectroscopy is a widely used technique for the evaluation of protein secondary structures that has a significant impact for the understanding of molecular biology.However,the quantitative analysis of protein secondary structures based on CD spectra is still a hard work due to the serious overlap of the spectra corresponding to different structural motifs.In this chapter,Tchebichef image moment combined with CD spectra has been proposed to quantitative determination of the protein six secondary structures for the first time.Furthermore,several specialized programs(SELCON3?CDSSTR?CONTIN?SSNN?K2D3)were used on the same reference set for a reliable analysis.Then the obtained results were compared with proposed method.For further proving the universality characteristics of the Tchebichef image moment approach,we also used another commonly large reference set(SP175)for a series of analysis.This study confirms that Tchebichef image moment approach improved the secondary structure determination of proteins in general,especially for proteins with turns and unordered structures,which is where many other methods are faulty.In addition,the proposed approach is not limited by the reference sets size,it can be trained with pretty much any reference set for which structures are available.Therefore,the Tchebichef image moment approach could be regarded as a useful tool to the quantitative analysis of protein secondary structures based on CD spectra.Chapter 4 An effective approach to the quantitative analysis of the skin-whitening agents in cosmetics with different substrates based on conventional UV-Vis determinationAlthough UV-Vis spectra have been applied to many fields,it still encounters some challenges in multi-component mixtures analysis due to serious spectral overlapping and different interferences.Tchebichef curve moment approach was developed and proposed for the quantitative analysis of the five skin-whitening agents in several cosmetic products with different substrates based on conventional UV-Vis determination for the first time.Tchebichef curve moment was extended from Tchebichef image moment and can be applied directly to the analysis of conventional chemical curve spectra.Furthermore,as comparison,MCR-ALS and PLS methods were also carried out to demonstrate the potential excellent abilities of our approach to the quantitative analysis of multi-component with UV-Vis spectra.The obtained results suggest that the proposed approach is more accurate and reliable,and it presents the higher ability of anti-interferences especially for overlapping signals and the unknown components derived from different substrates,which is not only expected to be an analytical technology applied to the quality assessment of cosmetic products,but also extends the application of moment methods and conventional 2D spectra in quantitative analysis of complex system.Chapter 5 Including main conclusions and outlook.