Spectroscopic techniques have been extensively used in the petroleum
industry for the characterization of crude oils. The present article shows the results of
the application of fluorescence techniques for the analysis of the density of Brazilian
crude oil samples. Fluorescence emission spectra of crude oil consist of relatively broad
bands in the visible region (from ca. 350 to 650 nm), the intensities of which tend to
accompany the API grade. Synchronous Fluorescence Spectroscopy (SFS) was
performed with a wavelength interval of 50 nm starting the excitation at 450 nm. Time-
Resolved Fluorescence Spectroscopy (TRFS) showed that the fluorescence lifetime is
related to the API value, lighter oils with higher API exhibiting a longer lifetime. The
present results demonstrate that fluorescence spectroscopy is useful in the
characterization of complex samples like crude petroleum.