Oxidation of Copper(I) in seawater at nanomolar levels

The oxidation and reduction of copper in air-saturated seawater and NaCl solutions has been measured as a function of pH (7.17-8.49), temperature (5-35ºC) and ionic strength (0.1-0.7 M). The oxidation rate was fitted to an equation for sodium chloride and seawater valid at different pH and media conditions: k . . pH- . /T- . I . I k . . pH- . /T- . I . I (sw) (NaCl) log 5 036 0 514 1764 915 1101 0 233 log 5 221 0 609 1915 433 1818 0 408 = + + = + + The reduction of Cu(II) was studied in both media for different initial concentration of copper(II). When the initial Cu(II) concentration was 200 nM, the copper(I) produced was 20% and 9% for NaCl and seawater, respectively. Considering the copper(I) reduced from Cu(II), the speciation and the contribution of these species to the kinetic process was studied. The Cu(I) speciation is dominated by the CuCl2 - species. On the other hand, the neutral chloride CuCl species dominates the Cu(I) oxidation in the range 0.1 M to 0.7 M chloride concentrations.

Assessment of the presence of pharmaceutical compounds in seawater samples from coastal area of Gran Canaria Island (Spain)

[EN]This study presents the evaluation of seven pharmaceutical compounds belonging to different commonly used therapeutic classes in seawater samples from coastal areas of Gran Canaria Island. The target compounds include atenolol (antihypertensive), acetaminophen (analgesic), norfloxacin and ciprofloxacin (antibiotics), carbamazepine (antiepileptic) and ketoprofen and diclofenac (anti-inflammatory). Solid phase extraction (SPE) was used for the extraction and preconcentration of the samples, and liquid chromatography tandem mass spectrometry (LC-MS/MS) was used for the determination of the compounds. Under optimal conditions, the recoveries obtained were in the range of 78.3% to 98.2%, and the relative standard deviations were less than 11.8%. The detection and quantification limits of the method were in the ranges of 0.1–2.8 and 0.3–9.3 ng·L−1, respectively. The developed method was applied to evaluate the presence of these pharmaceutical compounds in seawater from four outfalls in Gran Canaria Island (Spain) during one year. Ciprofloxacin and norfloxacin were found in a large number of samples in a concentration range of 9.0–3551.7 ng·L−1. Low levels of diclofenac, acetaminophen and ketoprofen were found sporadically.

Chemistry of Fe(II) in the presence of organic exudates from phytoplankton and of copper in seawater

Programa de doctorado de Oceanografía ; 2006-2008