Synthesis of a novel COF and its composite with PPY during cyclic voltammetric electropolymerization to prepare a new thin film microextraction device.

Abstract

<h4>Background</h4>Covalent organic frameworks (COFs) are new promising materials for separation purposes due to their high porosity, significant thermal and chemical stability, and tunable structures. Conductive polymers, such as polypyrrole (PPY), can further enhance sorbent performance by providing the capability of electrodeposition of COFs, as composites, on the surface of metallic substrates and creating additional adsorption sites, enabling the development of novel microextraction sorbents. Herein, a novel COF, COF-LU2, was synthesized and composited with PPY using an in-situ cyclic voltammetry (CV) electrodeposition method on a stainless-steel mesh, forming a thin-film microextraction (TFME) device with enhanced hydrophobicity and π-π interactions for improved sorption of aromatic analytes.<h4>Results</h4>The morphology and structure of the PPY@COF-LU2 composite were characterized using FT-IR, NMR, XRD, SEM, EDX, and BET techniques. The developed TFME technique, coupled with GC-FID, was applied for the direct-immersion sampling of BTEX in water samples. The extraction conditions were optimized using a Box-Behnken design. Under the optimal conditions, the procedure exhibited wide linear dynamic ranges (2-10000 μg L^-1), low limits of detection (0.5-1.0 μg L^-1), and excellent precision with intra- and inter-day RSDs of 2.6-5.0 % and 3.4-6.1 %, respectively. The procedure provided high recovery values (89.2-103.8 %) in real samples, highlighting the robustness and efficiency of the sorbent.<h4>Significance</h4>The facile fabrication of the PPY@COF-LU2-based TFME device demonstrates the feasibility of the in-situ CV electropolymerization strategy for preparing COF-polymer composites. This opens a new avenue for cost-effective fabrication of diverse microextraction devices incorporating various COFs and conductive polymers, with broad potential for analytical chemistry applications.