Rapid preparation of robust polyaniline coating on an etched stainless steel wire for solid-phase microextraction of dissolved bisphenol A in drinking water and beverages

Abstract

A new approach for rapid preparation of porous polyaniline (PANI) coating on a stainless steel (SS) wire was developed in nitric acid containing aniline. The SS wire was first etched in hydrofluoric acid and then used as a working electrode for electrodeposition of PANI coating. The etching procedure on a SS wire provides porosity necessary for higher extraction capability of PANI coating and for the extraction phase to hold firmly onto the SS fiber. The porous structure of the PANI coating prepared in nitric acid (PANI–NO₃) was more uniform than that prepared in sulfuric acid (PANI–SO₄). These PANI coatings were applied to solid-phase microextraction (SPME) of bisphenol A (BPA) coupled with high performance liquid chromatography with ultraviolet detection (HPLC-UV). Their SPME performance was compared and SPME conditions based on the PANI–NO₃ coating were further optimized. The linear range was 0.01–100 ng mL⁻¹ with a correlation coefficient of 0.9996. The relative standard deviation was 2.36% for a spiked sample with BPA of 10 ng mL⁻¹ (n = 5) and the limit of detection was 0.005 ng mL⁻¹. The fiber-to-fiber reproducibility of 6.41% was achieved for three PANI–NO₃ coated fibers prepared under the same conditions. Finally, the porous PANI–NO₃ coating was used for the selective and efficient preconcentration of dissolved BPA in drinking water and beverages. The recoveries of spiked BPA in the real samples ranged from 90.56% to 108.2%. The prepared PANI–NO₃ coated fibers have high mechanical strength and chemical stability, long lifetime, high extraction efficiency and good selectivity for the extraction of BPA in complex matrices.