Comparisons of N, N-dimethylformamide and 90% acetone as an extraction solvent for fluorometric determination of chlorophyll a from natural phytoplankton communities in the Southern Ocean

Abstract

Algal chlorophyllous pigments were extracted with two different solvents, N, N-dimethylformamide (DMF) and 90 percent acetone, using natural phytoplankton communities in the Southern Ocean. Concentrations of chlorophyll a 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 a 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 a concentrations. Phaeopigments concentrations extracted with DMF tended to be higher than those with 90 percent acetone. Total chlorophyllous pigments (chlorophyll a plus phaeopigments) were abut 10 percent higher in the former solvent than in the latter, considering the slope of the regression line (= 1.088).

南大洋で採集された天然植物プランクトン群集に対して、N,N-ジメチルホルムアミド(DMF)および90％アセトンの2種類の溶媒を用いて色素の抽出を行い、クロロフィルaおよびフェオ色素濃度を蛍光法によって求めた。前者の溶媒は第33次日本南極地域観測隊が用いたものであり、後者は従来の観測隊で用いられてきたものである。溶媒が異なってもクロロフィルa濃度には統計的に有意な差が認められなかった。フェオ色素に関しても溶媒の違いによる統計的有為差はみられなかった。しかしながら、フェオ色素の場合、クロロフィルaの場合に比べ相関が有意に低く、DMFで抽出したフェオ色素濃度の方が、90％アセトンで抽出した場合よりも高くなる傾向があった。クロロフィルaとフェオ色素を加えた全クロロフィル色素濃度の場合には、溶媒間の回帰直線の傾きを考慮すると、前者で抽出した方が後者よりも約10％ほど高かった。