Simultaneous determination of acidic phytohormones in cucumbers and green bean sprouts by ion-pair stir bar sorptive extraction-high performance liquid chromatography

A simple, sensitive and inexpensive method of ion-pair stir bar sorptive extraction (IP-SBSE) combined with high performance liquid chromatography -ultraviolet (HPLC-UV) detection was developed for the simultaneous determination of three acidic phytohormones (salicylic acid (SA), indole-3-acetic acid (IAA), and abscisic acid (ABA)) in vegetables. With the addition of cationic surfactant-cetyltrimethylammonium bromide (CTAB) in sample solutions, ion pair between CTAB and target phytohormones were formed, leading to an improvement of the extraction efficiency for target phytohormones by C 18 silica coated SBSE. The factors affecting the extraction efficiency of three target phytohormones by IP-C 18 coated SBSE were optimized, and the optimal experimental conditions were established. Under the optimal conditions, the limits of detection for SA, IAA and ABA obtained by IP-C 18 -SBSE-HPLC-UV were 2.7, 2.1 and 0.3   μg   L −1 , with the relative standard deviations of 6.0%, 5.0% and 8.3%, respectively, and the enrichment factor was 32–49-fold. The developed method was applied to the determination of SA, IAA and ABA in cucumbers and green bean sprouts, and the recoveries of SA, IAA and ABA for the spiked samples were between 72.8% and 109.5%.