Carbonized polydopamine as coating for solid-phase microextraction of organochlorine pesticides.

A facile preparation route for coating a stainless steel fiber with carbonaceous material derived from polydopamine is reported in this work. The self-oxidation induced polymerization of dopamine in alkaline solution enables growth of polydopamine on the inert surface of the fiber. The robust adhesion of dopamine to metal oxides ensured sufficient stability of the polymer coating. After carbonization of the polymer coating, the obtained carbon coated fiber was utilized for solid-phase microextraction and exhibited effectiveness in the extraction of organochlorine pesticides (OCPs) from aqueous solution. Extraction time, agitation speed and salt addition were optimized. The possible interference of humic acid on the extraction of these analytes was also investigated. The results showed that most of the analytes could be detected efficiently in the presence of humic acid at a concentration of 20mg/L. Under the optimized conditions, enrichment factors of 102-757 were obtained for the selected OCPs in aqueous solution. The proposed method provided low limits of detection (1.4-15 ng/L), good linearity (correlation coefficients>0.9971) and acceptable precision (relative standard deviations<16.3%).