APPLICATION OF THE ELIMINATION PRINCIPLE IN SPECTRAL EXPERIMENTS
| Authors | |
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| Year of publication | 2020 |
| Type | Article in Proceedings |
| Conference | XX. Workshop of Biophysical Chemists and Electrochemists |
| MU Faculty or unit | |
| Citation | |
| Web | https://www.sci.muni.cz/labifel/files/soubory/sbornik_2020.pdf |
| Keywords | Rhodamine 6G; UV-VIS spectra; elimination principle |
| Description | The elimination principle is based on the fact that certain parts of the overall experimental result show different dependencies on one of the set experimental parameters. The principle of elimination was developed and widely applied in electrochemistry (Elimination Polarography - EP and Elimination Voltammetry with Linear Scan - EVLS) in order to study electrode processes and create sophisticated platform for electroanalytical approaches [1-13]. While the chosen experimental parameter in EP is time and the elimination procedure uses linear combinations of time derivatives and integrals, in EVLS, the changing parameter is the polarization rate and elimination is the solution of the elimination function, expressed as linear combinations of total voltammetric currents measured at different scan rates [1,4,6,7]. The concept of a linear combination gave rise to the use of the elimination principle in spectral experiments as well. The basic attributes of the elimination principle are also preserved in spectral applications, i.e.: (i) in general n different parts of the experimental result can be eliminated by a linear combination of n+1 results, (ii) one experimental result is chosen as reference and other records registered with changed parameter they are related to it (normalized values), (iii) elimination coefficients or increment of values in appropriate linear combinations - functions play a significant role in the elimination procedure and (iv) the solution of functions provides other, very important and often hidden information. The elimination principle was applied to a spectral system, in which both a monomer and a dimer are present in equilibrium. Based on normalized spectra measured at three different analyte concentrations, where the concentration dependence of absorbance or molar ellipticity is linear (UV-Vis or CD spectra), theories for the calculation of the dimerization constant were theoretically derived. In addition, the proportion of spectra increments with reference, half and twice the analyte concentration gave the possibility to calculate the ratio RES (ratio), which should be independent of the wavelength monomer-dimer in the case of wavelength. The possible dependence of RES on wavelength may be proof that the studied system is more complicated and does not correspond to the model for which the theoretical relations were derived. The theoretical apparatus of elimination spectroscopy is now tested on known calibration system (Rhodamine 6G) [14-16], since we assume its application to a group of biologically important molecules, such as purines and pyrimidines, or their higher structures. |
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