Influence of the degree of solvent impurity on the spectrophotometric determination of chlorophylls in 80 % aqueous acetone and dimethyl formamide. Application to non-abrasive extraction of leaves of Citrus aurantium

Chlorophyll. (Chl) a and Chl b absorbances were determined in extracts from leaves of Citrus aurantium L, using the solvents diethyl ether (100 %), bu ffered 80 % aqueous acetone, and N,N'-dimethyl formamide (DMF) (99.83 %). T he respective standard deviations (sigma) and coefficients of variability ( CV) were used to establish the errors obtained when using impure solvents. Buffered 80 % aqueous acetone gave an error of 2.1 % for Chl a and 7.1 % fo r Chl b, while DMF gave errors of 3.5 and 6.7 %, respectively. For current Chl determination we propose a non-abrasive method, which extracts 15 leaf discs (diameter 6 mm) with 10 cm(3) of buffered 80 % aqueous acetone or DMF in hermetically sealed flasks during 24 h in darkness at 4 degrees C.