Application of a robust solid-phase microextraction fiber consisting of NiTi wires coated with polypyrrole for the determination of haloanisoles in water and wine

Abstract

In this study, the application of a solid-phase microextraction (SPME) fiber which was fabricated by electrolytically depositing polypyrrole (PPy) on a NiTi alloy support was investigated. The NiTi alloy was used as the support due to its superelasticity and shape memory properties and PPy is a suitable coating material since it offers facile synthesis and is a polar compound. Some parameters related to fiber fabrication, including the potential used for the electrodeposition, amount of electric charge and type of counterion, were subjected to multivariate optimization taking into account the uniformity, porosity and the adhesion of the fiber and, also the coating thickness on the support. In relation to method development for the determination of haloanisoles, the factors that affect the analyte uptake were also subjected to multivariate optimization using full factorial and response surface designs. The developed method exhibited correlation coefficients higher than 0.996, relative standard deviations lower than 16% and limits of detection ranging from 1 to 6 ng L⁻¹. The matrix effect caused by complex samples was overcome with the use of acetylated-halophenols as the internal standards, allowing the use of standard aqueous solutions for calibration. The proposed NiTi–PPy fiber exhibited equal or superior performance compared to some commercially available SPME fibers. Therefore, the presented fiber is an attractive alternative due to its high robustness and ease of preparation.