Electrochemical preparation of zinc oxide/polypyrrole nanocomposite coating for the highly effective solid-phase microextraction of phthalate esters.

In this work, zinc oxide/polypyrrole nanocomposite coating was fabricated on stainless steel and evaluated as a novel headspace solid-phase microextraction fiber coating for extraction of ultra-trace amounts of environmental pollutants, namely, phthalate esters, in water samples. The fiber nanocomposite were prepared by a two-step process including the electrochemical deposition of polypyrrole on the surface of stainless steel in the first step, and electrochemical deposition of zinc oxide nanosheets in the second step. Porous structure together with zinc oxide nanosheets with the average diameter of 30 nm were observed on the surface by using scanning electron microscopy. The effective parameters on extraction of phthalate esters (i.e., extraction temperature, extraction time, desorption temperature, desorption time, salt concentration, and stirring rate) were investigated and optimized by one-variable-at-a-time method. Under optimized conditions (extraction temperature, 90°C; extraction time, 40 min; desorption temperature, 270°C; desorption time, 5 min; salt concentration, 25% w/v; and stirring rate, 1000 rpm), the limits of detection were in the range of 0.05-0.8 μg/L, and the repeatability and fiber-to-fiber reproducibility were in the ranges of 6.1-7.3% and 8.7-10.2%, respectively.