Fast and environmentally friendly determination of salicylic acid in plant materials by sequential injection chromatography

Abstract

An improved procedure for determination of salicylic acid in plant materials is proposed. The phytohormone is extracted with water under microwave-assisted heating and the extract is directly analyzed by sequential injection chromatography with fluorimetric detection, thus avoiding time-consuming and wasteful sample clean-up steps. Isocratic elution (7 : 93 v/v acetonitrile/water) of the analyte was carried out in ca. 5 min, thus reducing the consumption of the organic solvent to 210 μL. A linear response was achieved from 0.5 to 8.0 mg L⁻¹, which corresponds to 10 to 160 μg g⁻¹ in the samples. The detection limit was estimated as 0.4 μg g⁻¹, with a coefficient of variation of 1.2% (n = 20). The procedure was successfully applied to soybean, jackfruit, and sugarcane leaves, and results were in agreement with those obtained by HPLC at the 95% confidence level. The procedure is a fast and greener alternative for answering the high demand for this analysis in agronomical studies.