Chemical bonding of cross-linked glutaraldehyde/chitosan on surface of a titanium wire to prepare a robust biocompatible SPME fiber for analysis of phytohormones in plants

A robust biocompatible solid-phase microextraction (SPME) fiber, so-called Ti/APTS/GA/CS, was prepared by chemical bonding of cross-linked glutaraldehyde-chitosan to the surface of a titanium wire using APTS. The fiber was applied for sampling of phytohormones in plant tissues, followed by HPLC-UV analysis. The structure and morphology of the fiber coating was investigated by FT-IR, SEM, EDX, XRD, and TGA techniques. A Box-Behnken design was implemented to optimize the experimental variables. The calibration graphs were linear over a wide linear range (0.5–200 μg L−1) with LODs over the range of 0.01–0.06 μg L−1. The intra-day and inter-day precisions were found to be 1.3–6.3% and 4.3–7.3%, respectively. The matrix effect values ranged from 86.5% to 111.7%, indicating that the complex sample matrices had an insignificant effect on the determination of phytohormones. The fiber was successfully employed for the direct-immersion SPME (DI-SPME-HPLC) analysis of the phytohormones in cucumber, tomato, date palm, and calendula samples.