FLUOROMETRIC ANALYSIS OF CHLOROPHYLL-A IN THE PRESENCE OF CHLOROPHYLL-B AND PHEOPIGMENTS

A fluorometric method is described which provides sensitive measuremen ts of extracted chlorophyll a free from the errors associated with con ventional acidification techniques. Fluorometric optical configuration s were optimized to produce maximum sensitivity to Chl a while maintai ning desensitized responses from both Chl b and pheopigments. Under th e most extreme Chl b :Chl a ratio likely to occur in nature (1 : 1 mol ar), the new method results in only a 10% overestimate of the true Chl a value, while estimates from older acidification methods are 2.5-fol d low. Under conditions of high pheopigment concentrations (pheo a : C hl a = 1 : 1 molar), the new method provides Chl a estimates that are equivalent to those determined from the acidification technique. The n ew simple method requires a single fluorescence determination and prov ides adequate sensitivity for small sample sizes (<200 ml) even in the most oligotrophic marine and freshwater environments.