A solid-phase microextraction platinized stainless steel fiber coated with a multiwalled carbon nanotube-polyaniline nanocomposite film for the extraction of thymol and carvacrol in medicinal plants and honey

A mechanically hard and cohesive porous fiber, with large surface area, for more strong attachment of the coating was provided by platinizing a stainless steel wire. Then, the platinized stainless steel fiber was coated with a multiwalled carbon nanotube/polyaniline (MWCNT/PANI) nanocomposite using electrophoretic deposition (EPD) method and applied for the extraction of thymol and carvacrol with direct-immersion solid-phase microextraction (DI-SPME) method followed by high-performance liquid chromatography-ultraviolet detection (HPLC-UV) quantification. To provide a larger coarse surface for the tightened attachment of coating on the fiber, a stainless steel wire was platinized using a suitable optimized EPD method. Different experimental parameters were studied and the optimal conditions were obtained as: pH of the sample solution: 2; extraction time: 60 min; salt content in the sample solution: 1% w/v NaNO3; desorption time: 60 min; type and volume of the desorption solvent: acetonitrile, 100 mu L. Under the optimized conditions, limits of detection (LODs) were 0.6 and 0.8 mu gmL(-1) for thymol and carvacrol, respectively. Linear dynamic range (LDR) for the calibration curves of both analytes were 1-80 mu g mL(-1). Relative standard deviation (RSD%, n = 6) was 6.8 for thymol and 12.7 for carvacrol. The proposed fiber was successfully applied for the recovery and determination of thymol and carvacrol in thyme, savory, and honey samples. (C) 2015 Elsevier B.V. All rights reserved.