Determination of L-ascorbic acid in Lycopersicon fruits by capillary zone electrophoresis

This study shows an improved method for the determination Of L-ascorbic aci d (L-AA) in fruits of Lycopersicon by capillary zone electrophoresis (CZE). Two backgrounds electrolytes (BGEs) have been tested: (i) 400 mM borate at pH 8.0 and 1 x 10(-2)% hexadimethrine bromide, for the separation of Eulyc opersicon subgenus species; and (ii) as in BGE(i) but supplemented with 20% (v/v) acetonitrile, for the separation of species of the Eriopersicon subg enus. The present procedures were compared with two routine methods enzymat ic assay and potentiometric titration with 2,6-dichlorophenol-indophenol. W hile these routine methods presented some difficulties in quantifying L-AA in several Lycopersicon fruits, CZE was successfully applied in all the ana lyzed samples. The proposed CZE protocols give lower detection limits (<0.4 mug ml(-1)); are cheaper, quicker, and highly reproducible; and can be app lied to analyze large series of samples (ca. 50 samples per day) which is u tmost importance, not only in screening trials for internal quality and tom ato breeding programs, but also in systematic and routine characterization of Lycopersicon fruits. (C) 2001 Academic Press.