Dendritic copolymer electrode for second harmonic alternating current voltammetric signalling of pyrene in oil-polluted wastewater.

A sensitive dendritic star copolymer-based sensor for pyrene (PY), was developed by in situ electrosynthesis of generation 3 poly(propylene thiophenoimine)-co-poly(3-hexylthiophene) (G3PPT-co-P3HT) on a gold disk electrode (Au). The electrochemical reactivity and the signal transduction properties of the Au|G3PPT-co-P3HT co-polymer electrode were studied by second harmonic alternating current voltammetry (SHACV) and alternating current voltammetry (ACV), respectively. SHACV analysis confirmed the occurrence of Faradaic electrode process (with a standard rate constant, k0 value of 3.36 cm s-1), possibly originating from the surface-confined thiophene groups of the co-polymer electrode. The ACV responses of the Au|G3PPT-co-P3HT electrode to pyrene gave a linear range (LR) of 2.73-26.86 nM and a limit of detection (LOD) of 1.34 nM PY. The low LOD value suggests that the PY sensor has promise for monitoring compliance to the World Health Organization (WHO) approved limit for polyaromatic hydrocarbons (PAHs) in wastewater, which is 3.93 nM. The sensor was used to determine PY levels in oil-polluted wastewater samples, which were found to contain 4.93-23.49 nM PY, depending on how far into the sea the samples were collected. The high recovery rate obtained for the oil-polluted seawater samples, indicate that ACV signalling protocol makes the Au|G3PPT-co-P3HT electrode very suitable for application in samples that have complex matrices.