Development of an electrochemical sensor for detecing polycyclic aromatic hydrocarbons in water

Policiklički aromatski ugljikovodici (PAH) organska su zagađivala široko rasprostranjena u vodenom okolišu. Zbog opasnosti koju predstavljaju za zdravlje i život vodenih organizama i čovjeka, javlja se sve veća potreba za brzim i jeftinim metodama koje bi omogućile ranu detekciju ovih spojeva u okolišu. Policiklički aromatski ugljikovodici utječu na strukturu i organizaciju sloja lipida elektrostatski adsorbiranog na površini živine elektrode, a spomenuta se interakcija može pratiti metodom brze cikličke voltammetrije. Ovaj rad opisuje razvoj elektrokemijskog senzora sa živinom mikroelektrodom modificiranom elektrostatski adsorbiranim miješanim slojem fosfolipida i triglicerida, kao dio djelomično automatiziranog protočnog sustava za ranu detekciju policikličkih aromatskih ugljikovodika u vodama.Polycyclic aromatic hydrocarbons (PAH) are organic pollutants ubiquitous in the aquatic environment. Considering the danger PAH-s pose to the health of aquatic organisms and humans, there is an increasing need for fast and reliable methods enabling early detection of these compounds in the environment. PAH-s influence the structure and organisation of a lipid layer electrostatically adsorbed on the surface of a mercury electrode, which can be monitored electrochemically using fast cyclic voltammetry. This work shows the development of an electrochemical sensor with a mercury microelectrode modified by a mixed lipid layer of phospholipids and triglycerides as a part of a semi-automated flow system for the early detection of polycyclic aromatic hydrocarbons in natural waters

In-situ electrochemical method for detecting freely dissolved polycyclic aromatic hydrocarbons in waters

A new sensing system for polycyclic aromatic hydrocarbons (PAH) in waters is being developed. The system consists of a wafer based device with chip-based mercury (Hg) on platinum microelectrode as working electrode and platinum auxiliary electrode, incorporated in to a flow cell system with an external reference electrode. Hg microelectrode was coated with a phospholipid/triglyceride mixed layer and interactions between anthracene, phenanthrene, pyrene and fluoranthene and the layer were monitored using rapid cyclic voltammetry (RCV). The layer proved sensitive to interactions with PAHs in “organic matter free” seawater, with the detection limits of 0.33 μg/L for phenanthrene, 0.35 μg/L for pyrene, 0.15 μg/L for anthracene and 0.32 μg/L for fluoranthene. Tested interferences, such as sodium humate, dextran T–500 and bovine serum albumin, representative humic substances, polysaccharides and proteins, did not have an influence on the layer response. The system was also tested with a river water sample where concentrations of PAHs were determined using the standard addition method and compared to the results obtained by using gas chromatography–mass spectrometry (GC–MS). The concentration of total PAH obtained by the standard addition method is about 80% lower compared to the results obtained by GC MS analysis. The difference is explained by the fact that the electrochemical method measures water-soluble and free PAHs while chromatographic methods measures both dissolved and particulate/organic PAH

Dissolved trace metals and organic matter distribution in the northern Adriatic, an increasingly oligotrophic shallow sea

We report a monthly distribution of Zn, Cd, Pb, Cu, Ni and Co, biologically relevant trace metals (TMs), within one year, in the productive surface layer at two stations with different trophic characters in the northern Adriatic (NA). The TM data was accompanied by a multivariable dataset, including dissolved organic carbon (DOC), surface- active organic substances (SAS), nitrogen containing polymeric organic material (N-POM), nutrients, pH, dissolved O2 , chlorophyll a (Chl a), seawater temperature, and the Po River discharge rate. At the eu- to mesotrophic station 108, the concentrations of dissolved TMs were 5– 116 nM for Zn, 0.04–0.18 nM for Cd, 0.05–0.63 nM for Pb, 3–17 nM for Cu, 4–11 nM for Ni, and 0.2– 1.2 nM for Co, while at the oligotrophic station 107, they were 6–224 nM for Zn, 0.03–0.16 nM for Cd, 0.05–1.25 nM for Pb, 3–17 nM for Cu, 4–19 nM for Ni, and 0.1–0.7 nM for Co. The characterization of organic matter (OM) in conjunction with the analysis of correlations with TMs indicated that the OM–TMs interactions differed between the two stations ; namely, the freshly produced OM detected at station 108 was probably involved in the complexation of Cu, Co, Cd, and Ni, whereas at station 107, such complexation processes were not present. Accumulation of DOC was observed during the summer months at both stations. Our results present a significant contribution to biogeochemical studies in the NA by focusing on the complexity of TM–OM interactions, which is a prerequisite for interpretation of their responses to local and global changes