Ref. No. [UMCES]CBL 2013-015
ACT VS12-02
EEM fluorescence maps of each of the five challenge compounds, dosed at a
concentration of 50 ppb, are presented along with the region of the optical window of the
UviLux-CDOM (Figure 1) and UviLux-HC (Figure 2) filter sets. Excitation and Emission
maximums of the challenge compounds varied by over 100 nm, with Quinine Sulfate mapping
most closely with the optical window UviLux-CDOM filter set and Carbazole mapping most
closely with the optical window of the UviLux-HC filter set. Response curves for both
fluorometers were generated against each of the challenge compounds over concentrations
ranging from 1 – 1000 ppb (see Fig. 3 for the UviLux-CDOM and Fig. 4 for the UviLux-HC).
Results show instrument response (in mV) presented against both concentration and estimated
EEM
QSE
(Quinine Sulfate equivalent) fluorescence intensity for each challenge compound.
Baseline signal in deionized water was approximately 375 mV for the UviLux-CDOM and HC
units. As expected by factory design, the voltage output response to increasing concentration
(panel A) was linear up to detector saturation where ambient overload rejection circuitry
produced an apparent quenching in maximum signal output (see Fig 4, responses to Carbazole
and NSDA). The instrument response to increasing concentration was significantly less for those
compounds with fluorescence maxima outside the optical window wavelength centers of the
instruments filter set and hence lower predicted EMM
QSE
intensities (panel B).
Ancillary water quality conditions for turbidity and CDOM are presented for each
challenge compound at each of the concentrations tested. In general the challenge compounds,
except for BB3, had little effect on turbidity levels and the instrument response reflected the
fluorescence properties of the challenge compound. BB3 additions increased measured turbidity,
but since neither of the UviLux fluorometers were responsive to this particular challenge
compound no obvious quenching effects were evident at the higher challenge concentration
levels. Spectroscopically derived CDOM levels were compound specific (Fig. 5, panel B) and
reached asymptotes above 10 ppb additions, well below the instruments’ response capacity
(>100 ppb for QS and #2 diesel fuel oil).
12
