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Method 445.0 In Vitro Determination of Chlorophyll a and Pheophytin ain Marine and Freshwater Algae by Fluorescence
Citation:
Arar, E. J. AND G. B. COLLINS. Method 445.0 In Vitro Determination of Chlorophyll a and Pheophytin ain Marine and Freshwater Algae by Fluorescence. U.S. Environmental Protection Agency, Washington, DC, 1997.
Impact/Purpose:
see description
Description:
This method provides a procedure for low level determination of chlorophyll a (chl a) and its magnesium free derivative, pheophytin a (pheo a), in marine and freshwater phytoplankton using fluorescence detection.(1,2) Phaeophorbides present in the sample are determined collectively as pheophytin a. For users primarily interested in chl a there is currently available a set of very narrow bandpass excitation and emission filters (Turner Designs, Sunnyvale, CA) that nearly eliminates the spectral interference caused by the presence of pheo a and chlorophyll b. The difference between the modified method and the conventional fluorometric method is that the equations used for the determination of chlor a without pheo a correction (uncorrected chlor a), are used instead of the equations for "corrected chlor a". This EPA laboratory has evaluated the modified filters and found the technique to be an acceptable alternative to the conventional fluorometric method using pheo a correction. (3)