Electrochemically controlled in-tube solid phase microextraction of naproxen from urine samples using an experimental design

Abstract

A new in-tube solid phase microextraction approach named electrochemically controlled in-tube solid phase microextraction (EC in-tube SPME) has been reported. In this approach, in which electrochemistry and in-tube SPME were combined, the total analysis time was decreased and the sensitivity was increased. After electropolymerization of pyrrole on the inner surface of a stainless steel tube, the polypyrrole (PPy)-coated in-tube SPME was coupled on-line to high performance liquid chromatography (HPLC) to achieve automated in-tube SPME-HPLC analysis. After the completion of the EC-in-tube SPME-HPLC system, the PPy-coated tube was used as a working electrode for the uptake of naproxen. It was found that the extraction efficiency could be significantly enhanced using the constant potential. Plackett–Burman design was employed for screening, to determine the variables significantly affecting the extraction efficiency. The significant factors were then optimized using a Box–Behnken design. The linear range and detection limit (S/N = 3) were 0.5–1000 and 0.07 μg L⁻¹, respectively. Urine samples were successfully analyzed by the proposed method.