Introduction of electropolymerization of pyrrole as a coating method for stir bar sorptive extraction of estradiol followed by gas chromatography.

In this study, fabrication of a stir bar sorbent is presented by electropolymerization of pyrrole via cyclic voltametry for the first time. The fabricated stir bar was applied as an efficient sorbent for extraction and pre-concentration of trace amounts of estradiol in urine samples through stir bar sorptive extraction (SBSE) method followed by gas chromatography-flame ionization detector. For this purpose, first the surface of stainless steel rod was modified by hyroxide functional group. Then electropolymerization of pyrrole monomers took place on the surface of functionalized steel rod under the optimized conditions including pyrrole concentration of 0.03 mol L, equal concentration ratio of pyrrole to sodium dodecyl sulfate, 10 cycles of cyclic voltammetry and potential scan rate of 10 mV s. Characterization of the produced sorbent was confirmed by scanning electron microscope imaging and energy-dispersive X-ray and infrared spectroscopy. Evantually, under the optimized conditions, the stir bar sorbent was used for extraction of estradiol from human urine samples. The presented SBSE method showed a good linearity range of 50-700 ng mL with coefficient of determination 0.9910, limit of detection 10 ng mL and theoretical limit of quantification 33 ng mL. Moreover, better enrichment factor (87) and extraction recovery (43%) were obtained using the fabricated stir bar compared with two commercial stir bars for estradiol. The intra- and inter-bar relative recoveries were obtained 92.0% and their coefficient of variations were less than 5.4%.