Effective Solvents and Extraction Periods Employed in Phytoplankton Carotenoid and Chlorophyll Determinations

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Abstract
High-performance liquid chromatography (HPLC) showed that spectrophotometric determinations of algal lipophilic pigments are often biased by the choice of extraction solvent. Several commonly used extraction solvents and extraction periods were tested on diverse phytoplankton species isolated from the Neuse River, NC [North Carolina, USA]. Extraction solvents included 100% acetone, 90% acetone-10% distilled deionized water (DDW), 50% acetone-50% methanol, and 90% methanol-10% DDW. Extraction efficiencies varied significantly among genera. For the diatom Cyclotella meneghiniana, at least 3 solvents extracted all lipophilic pigments with equal efficiency, but 50:50 acetone-methanol was clearly superior for the chlorophycean Chlorella vulgaris. A host of differences in extraction efficiencies and extraction times were observed when eukaryotic and prokaryotic (blue-green algae) phytoplankton were compared. A single extraction technique that could consistently provide quantitative and uniform pigment yields from diverse phytoplankton communities could not be found. HPLC techniques can be rapidly and routinely employed to determine appropriate extraction protocols for lipophilic pigments of interest in specific aquatic ecosystems.