Ref. No. [UMCES] CBL 2013-020
ACT VS12-03
SUMMARY of INSTRUMENT RESPONSE ACROSS ALL TEST APPLICATIONS
The CDOM, Crude Oil, and Refined Fuel sensors on the Turner C3 in situ fluorometer all
exhibited the expected linear signal response to challenge analyte concentration with the
response slope (sensitivity) mapping to the overlap of the compound’s fluorescence properties to
the optical configuration of the instrument package (Figs. 42-44). Focusing on EEM
QSE
intensities corresponding to the 0-1000 ppb range of dissolved analyte, the differential response
of the suite of sensors provided in the Turner C3 package is evident. While the CDOM and
Crude Oil sensors readily track changes in QS, traditionally used as the calibrant for CDOM,
they were insensitive to components of refined fuels (carbazole, NDSA, #2 Diesel Fuel). In
contrast, the Refined Fuel sensor exhibited a dampened response to QS but readily detected
concentration changes in NDSA, #2 Diesel and crude oils in various dispersion states.
Additionally, the Refined Fuel sensor exhibited lower sensitivity to environmental background
which was readily detected by the CDOM and Crude Oil sensors albeit with different
sensitivities. From the comparison of fluorescence sensor performance with respect to optically
relevant EEM
QSE
space, it should be evident that an understanding of ambient water conditions
and choice of calibrant compound are critical for robust interpretation of hydrocarbon-specific
fluorescence patterns in natural waters.
In general,
care should be taken in specific
interpretation of environmental fluorescence signals in absence of analytical reference
samples.
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