Comparisons of N, N-dimethylformamide and 90% acetone as an extraction solvent for fluorometric determination of chlorophyllα from natural phytoplankton communities in the SouthernOcean

Abstract

Algal chlorophyllous pigments were extracted with two different solvents, N, N-dimethylformamide (DMF) and 90% acetone, using natural phytoplankton communities in the Southern Ocean. Concentrations of chlorophyll α and phaeopigments were determined fluorometrically. The former solvent was employed during the 33rd Japanese Antarctic Research Expedition (JARE-33) while the latter has been used during previous JAREs. Statistical analyses showed that chlorophyll α concentrations were equivalent although the solvents were different. No significant difference was observed between concentrations of phaeopigments extracted with the different solvents either. The correlation coefficient obtained between phaeopigments concentrations was significantly lower than that between chlorophyll α concentrations. Phaeopigment concentrations extracted with DMF tended to be higher than those with 90% acetone. Total chlorophyllous pigments (chlorophyll α plus phaeopigments) were about 10% higher in the former solvent than in the latter, considering the slope of the regression line (=1.088).