| Fluorescence spectroscopy is an attractive alternative to chromatographic techniques for determination of dissolved polycyclic aromatic hydrocarbons (PAHs). The high sensitivity of fluorescence spectroscopy permits low ppb detection limits of dissolved PAHs, the most bio-available fraction, without time and labor intensive preconcentration and extraction. Two principal disadvantages associated with fluorescence spectroscopy are overcome by combining instrumentation advances with chemometric data analysis. An entire excitation-emission matrix (EEM) fluorescence spectrum is imaged on a charged coupled device (CCD) chip and analyzed in conjunction with previously collected standard spectra by “three-way” methods such as Parallel Factor Analysis (PARAFAC). PARAFAC based analysis of the collected EEM data permit mathematical resolution of the analyte signature from most fluorescent backgrounds. This alleviates the need to find a single excitation and emission wavelength set that is unique to the analyte of interest. Furthermore, collection of single measurement EEM fluorescence spectra is quicker than collection of scanning excitation emission matrix fluorescence or synchronous fluorescence for a given signal to noise level. Application of a fiber-optic based, single measurement spectrophotometer for determination of targeted PAHs will be demonstrated and the speed, accuracy, and detection limit of EEM fluorescence will be compared to that of chromatographic methods following solid phase extraction. |
