On‐Chip Electromembrane Solid‐Phase Microextraction Using a Polypyrrole/Zirconium‐Based Metal–Organic Framework/Ti 3 C 2 T x Titanium Carbide Composite Coating for the Determination of Phenoxyacetic Acid Herbicides in Environmental and Food Samples

ABSTRACT In this study, a miniaturized electromembrane‐surrounded solid‐phase microextraction (EM‐SPME) device was integrated into a microfluidic chip. It was employed for the extraction of phenoxyacetic acid herbicides, including 2‐methyl‐4‐chlorophenoxyacetic acid (MCPA) and 2,4‐dichlorophenoxyacetic acid (2,4‐D), in environmental and food samples. The separation and determination of the analytes was performed by GC‐MS. A nanostructured polypyrrole/zirconium‐based metal–organic framework/Ti 3 C 2 T x titanium carbide (MXene) fiber, synthesized electrochemically, was used as the acceptor adsorbent and also electrode. The simultaneous application of an electric field and nanocomposite‐based adsorption enabled efficient preconcentration of the analytes within a compact and low‐solvent system. Effective parameters on the extraction of the analytes were investigated and optimized. Under optimized conditions, the developed EM‐SPME–GC‐MS method exhibited limits of detection of 0.3 µg L −1 for both analytes and linear ranges of 1–1000 µg L −1 for MCPA and 2,4‐D ( R 2 ≥ 0.9934). Intraday and interday RSDs% were below 7.6% and 10.2% respectively, demonstrating satisfactory precision. The method was validated through real sample analysis in river water, cucumber, and rice extracts, achieving recoveries from 89% to 119%. The chip consumes 10 µL of 1‐octanol as SLM and 250 µL of methanolic tetrabutylammonium bromide for derivatization per analysis (total < 0.26 mL organic solvent), which is markedly lower than conventional liquid–liquid extraction/solid phase extraction workflows.