Application of asymmetric model in analysis of fluorescence spectra of biologically important molecules

• Published in: Journal of fluorescence 2007-05, Vol.17 (3), p.319-329
• Main Authors: Kalauzi, Aleksandar, Mutavdzić, Dragosav, Djikanović, Daniela, Radotić, Ksenija, Jeremić, Milorad
• Format: Article
• Language: English
• Subjects: Algorithms; Aromatic compounds; Asymmetry; Benzene Derivatives - chemistry; Catechol; Catechols - chemistry; Emission spectra; Excitation spectra; Fluorescence; Hydroquinone; Hydroquinones - chemistry; Luminescent Measurements - methods; Mathematical analysis; Mathematical models; Mixtures; Models, Theoretical; Organic chemistry; Phenols - chemistry; Phenylalanine; Phenylalanine - chemistry; Probability; Spectrometry, Fluorescence - methods; Tryptophan; Tryptophan - chemistry
• ISSN: 1053-0509; 1573-4994
• DOI: 10.1007/s10895-007-0175-3

Having a valid mathematical model for structureless emission band shapes is important when deconvoluting fluorescence spectra of complex molecules. We propose a new asymmetric model for emission spectra of five organic molecules containing aromatic ring: catechol, coniferyl alcohol, hydroquinone, phenylalanine and tryptophan. For each molecule, a series of emission spectra, varying in excitation wavelength, were fitted with the new model as well as with two other analytical expressions: log-normal, described previously in the literature, and sigmoid-exponential. Their deconvolution into two, three and four Gaussian components was also performed, in order to estimate the number of symmetric components needed to obtain a better fitting quality than that of the asymmetric models. Four subtypes of the new model, as well as the log-normal one, did not differ significantly in their fitting errors, while the sigmoid-exponential model showed a significantly worse fit. Spectra of two mixtures: hydroquinone-coniferyl alcohol and hydroquinone-tryptophan were deconvoluted into two asymmetric and four Gaussian components. Positions of asymmetric components of mixtures matched those of separate molecules, while Gaussian did not. Component analysis of a polymer molecule, lignin, was also performed. In this more complex case asymmetric and Gaussian components also grouped in alternating positions.