Time-resolved fluorescence polarization anisotropy of multimodal samples: the asphaltene case |
| |
Authors: | A Bruno M Alfè A Ciajolo C de Lisio P Minutolo |
| |
Institution: | (1) Centro di Ricerca e Sviluppo “Coherentia”, CNR-INFM, Unità di Ricerca di Napoli, and Dipartimento di Scienze Fisiche, Università di Napoli “Federico II”, Complesso di Monte S. Angelo, Via Cintia, 80126 Napoli, Italy;(2) Centro Regionale di Competenza “Analisi e Monitoraggio del Rischio Ambientale” (CRdC-AMRA), Via Nuova Agnano 11, 80125 Napoli, Italy;(3) Istituto di Ricerche sulla Combustione, CNR, P. le Tecchio 80, 80126 Napoli, Italy |
| |
Abstract: | In this work we describe an application of the time-resolved fluorescence polarization anisotropy (TRFPA) technique to the
analysis of asphaltenes, complex mixtures of high-molecular weight compounds, typically present in petroleum oils. Our asphaltene
samples consist of nanometer-sized polydispersed particles, whose lighter fraction showed a relatively high fluorescence quantum
yield. Most of the fluorescence intensity observed from the complex sample originated from a well defined sample fraction
presenting a large fluorescence yield. Consequently, the TRFPA analysis only provided the average size of more fluorescing
particles, that, in our case, were the smaller ones. Larger and less fluorescing aggregates did not significantly contribute
to the TRFPA signal. Hence, to overcome intrinsic limitations of the TRFPA technique in characterizing multimodal samples,
we preliminarily fractionated our complex samples by means of size exclusion chromatography (SEC), thus obtaining nearly monomodal
fractions of the original samples. This procedure allowed to estimate also the size of less fluorescing and larger particles.
A comparison of particle size estimate by means of TRFPA and SEC methods was also used to acquire information about occurrence
of aggregation phenomena, and about the kind and strength of the chemical bonds linking chromophores to each other or to their
parent particle.
PACS 82.53.Uv; 82.80.Bg; 47.57.E- |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|