Simultaneous determination of phytohormones containing carboxyl in crude extracts of fruit samples based on chemical derivatization by capillary electrophoresis with laser-induced fluorescence detection.

An efficient and sensitive capillary electrophoresis with laser-induced fluorescence detection (CE-LIF) method has been developed for the simultaneous determination of phytohormones containing carboxyl group, including gibberellic acid, indole-3-acetic acid, abscisic acid, jasmonic acid, indole butyric acid, 1-naphthalene acetic acid and 2,4-dichloro-phenoxy acetic acid, based on the chemical derivatization with 6-oxy-(acetypiperazine) fluorescein. Using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide as the condensing reagent, the derivatization reaction completed at 60°C in 60 min and the derivatization limits could reach 20 nmol L(-1). The formed derivatives of seven phytohormones have been separated and quantified within 20 min. The linearity was found in the range of 0.01-1 μmol L(-1) and the limits of detection were 1.6-6.7 nmol L(-1) (S/N=3). The proposed method has been applied to analyze the crude extract of 0.5 g banana samples directly without further purification and the recoveries varying from 90.7 to 106.1%.