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Total Scanning Fluorescence
Total Scanning Fluorescence (TSF) is a semi-quantitative
analytical technique that is selectively sensitive to
aromatic compounds and, as such, is a valuable tool
for detecting the presence of petroleum related hydrocarbons
in sediment extracts. Increasing TSF intensity (expressed
in arbitrary intensity units) generally corresponds
to increasing aromatic hydrocarbon concentrations in
sediment extracts.
High Level Oil Sample
Sediments containing upward-migrated oil contain a
higher concentration of larger aromatic compounds (3
or more benzene rings) and fluoresce at longer wavelengths,
whereas sediment extracts containing upward-migrated
gas or condensate fluoresce at shorter wavelengths.
TSF patterns are typically insensitive to bacterial
alteration except in severely biodegraded samples.
Low Level w/ Perylene
The TSF parameter R1 gives an estimate of the ratio
of three and four-ring aromatics to two-ring aromatics.
For extracts with high TSF maximum intensity, R1 values
greater than 2 typically indicate the presence of mature
hydrocarbons.
A three-dimensional spectrum is acquired using software
written for Perkin-Elmer Model LS 50B Fluorometers.
A sample extract is placed in the pre-calibrated fluorometer,
and scanned over a specified range of excitation wavelengths
while measuring the resulting fluorescence emission
intensities over a specified range of emission wavelengths.
The resulting data is used to evaluate the sample extract
for the presence of petroleum related aromatic hydrocarbons.
