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Developing an Electrochemical Sensor for the Detection of Dissolved Polycyclic Aromatic Hydrocarbons in Water

Increasing amounts of pollutants in the aquatic environment urge the development of simple and low cost methods for early detection of these dangerous substances. Such pollutants include polycyclic aromatic hydrocarbons (PAHs), hydrophobic molecules with potentially cargenogenic and mutagenic effects on the aquatic organisms. PAHs which are more hydrophobic usually adsorb and associate with organic particles in the aquatic environment, while PAHs which are less hydrophobic can be present in the dissolved form, which makes them more available for uptake by aquatic organisms. We are thus developing an electrochemical sensor which would be used for early detection of the dissolved fraction of PAHs present in waters. It has been found that PAHs can interact with phospholipid monolayers on a mercury electrode surface, causing a disruption of the monolayer fluidity and structure. This interaction can be monitored electrochemically by means of rapid cyclic voltammetry using a semi-automated flow cell system which incorporates a chip – based mercury microelectrode[1]. A mixed layer of palmitoyl-2-oleoyl-sn-glicero-3-phosphocholine and triolein, an oleic acid triglyceride, in 3:1 molar ratio, adsorbed onto a mercury microelectrode, was used as a sensing element for PAH detection. The system proved sensitive to the presence of four different PAH molecules, namely anthracene, phenanthrene, pyrene and fluoranthene, in different matrices, with a limit of detection of 0.3 ug L-1[2]. The performance of the system was tested on a natural river sample, in order to compare the sensitivity of the electrochemical sensor with a conventional GC – MS method used for determination of PAHs in natural samples. Further optimisation of the system is being carried out in order to improve sensitivity and enable subsequent use of the system in-situ. References: 1. Z. Coldrick, A. Penezic, B. Gasparovic, P. Steenson, J. Merrifield, A. Nelson, High throughput systems for screening biomembrane interactions on fabricated mercury film electrodes. J. Appl. Electrochem. 2011, 41. 939-949 2. A. Penezić, B. Gašparović, D. Stipaničev, A. Nelson. In-situ electrochemical method for detecting freely dissolved polycyclic aromatic hydrocarbons in water, Environmental Chemistry 2014, 11. 173-180

Polycyclic aromatic hydrocarbons; Sensor; Voltammetry

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