Natural water fingerprinting and bioaerosol detection by multidimensional fluorescence spectroscopy.

摘要

Multidimensional fluorescence spectroscopy is a powerful tool for analyzing complex real world samples having inherent fluorescence properties. Steady-state and time-resolved fluorescence methods were used to utilize fluorophores found in natural waters for classification to their location of origin. Steady state three-way date-ordered excitation-emission matrices (DO-EEMs) were recorded for water samples during a regional watershed study and a national three port study. Time-resolved excitation-emission spectroscopy was also conducted on the three port samples to produce four-way data, referred to as time-resolved excitation emission matrices (TREEMs). Such multivariate data are well suited for treatment by multi-way Partial Least Squares Discriminant Analysis (NPLS-DA), a supervised pattern recognition regression method. Classification results are presented for the regional steady state fluorescence fingerprinting study as well as for the three-port fingerprinting study, using both DO-EEM and TREEM data. The identification of geographic origin of water samples was possible without physical or chemical separation of components by NPLS-DA classification of multidimensional fluorescence data. This fingerprinting technique shows great promise as a forensic tool for the enforcement of ballast water exchange regulations.; A novel time-resolved integrated laser-induced fluorescence (TRI-LIF) instrument was designed and constructed for detection of airborne biological materials. This approach focused on improving resolution of aerosols by intrinsic fluorescence decay time. Existing fluorescence-based bioaerosol detection instruments experience high false positive rates in polluted areas, resulting from non-biological fluorescent aerosols. In this work, addition of the decay time dimension was traded for spectral resolution to avoid the interference by emission overlap and reduce the incidence of false alarms by fluorescence lifetime discrimination. Results of instrument characterization and preliminary particle experiments, using pyrene alone and pyrene adsorbed on alumina, are discussed in this text.