Fluorescence contouring analysis of DOC Intercalibration Experiment samples: a comparison of techniques
Paula G. Coblea, Christopher A. Schultzb and Kenneth Mopperb
aDepartment of Oceanography, University of Washington, Seattle, WA 98195, USA
bChemistry Department, Washington State University, Pullman, WA 99164-4630, USA
Summary
This paper presents a comparison of calibration techniques prior to analyzing the dissolved organic matter. Two techniques have been compared and found whether or not the information about dissolved organic matter is correct? Unconcentrated water samples were used were used. Four replicate acidified samples of each water type and two unacidified replicates were used.
Method 1
SPEX Industries Fluorolog 2 was used to obtain excitation emission spectra. Excitation and emission wavelength ranges were from 260 and 455 nm and from 270 to 510 nm with an interval of 5 nm for both. The data was normalized to the intensity of water Raman scatter peak at (Ex/Em) = 275/303. The water Raman peak was also used to calibrate fluorescence and distilled water was subtracted to eliminate water Raman scatter peaks.
Method 2
Hitachi Model F3010 scanning spectrofluorometer was used to obtain EEMs. Excitation spectra were recorded with wavelengths ranging from 220 to 440 nm at 2 nm interval. The emission spectra were recorded in the range of 240 to 540 nm with a gap of 1 nm. All the spectra were corrected using 1 ppb Quinine sulfate solution at (Ex/Em) = 350/450.
Results and Discussion
Two types of fluorescence were observed. Humic like at 230, 340/440 was observed in deep water, river, and oxygen minimum samples. Protein like fluorescence was observed at 275/305 in surface water samples. The position of maximum was not same for humic like matter in method 1. The surface sample was dominated by protein like fluorescence. Method 1 also gave protein like fluorescence in river samples. Protein like fluorescence was much more intense using method 2. The comparisons of fluorescence intensities for the two methods are given in the table (Table 1) below.
Reviewer: Aamir Alaud Din