A strategy to enhance the antifouling property of coating for direct immersion solid phase microextraction

•A Nafion modified polyaniline coating was prepared.•It showed improved selectivity and stability.•It exhibited enhanced robustness in direct contact with complex matrix.•It had high extraction capacity to parabens.

This paper presents a new approach for improving the antifouling property of solid-phase microextraction (SPME) coating. The SPME fiber was fabricated by electrodeposition of polyaniline (PANI) on stainless steel wire, followed by covering with an external layer of Nafion. The Nafion layer was able to block the interfering components in the matrix while the fiber was used for the direct extraction of several parabens. At the same time, the selectivity and stability of the SPME fiber was also improved. The adsorption coefficient and saturation-adsorption amount were determined, which showed that the extraction capability of the resulting fiber was similar to that of the original PANI fiber toward parabens. In addition, the fiber exhibited enhanced robustness in direct contact with complex matrix such as orange juice. After it was used for 110–150 adsorption–desorption cycles, its extraction efficiency decreased by 14–16% compared with the maximum measured value. This was a dramatic improvement when compared with the PANI fiber. Hence, the fiber was suitable for direct immersion SPME.