Determination of copper in seawater by anodic stripping voltammetry using ethylenediamine

Abstract

The complexlng properties of ethylenediamine (en) were Investigated as a means of performing the analysis of ligandexchangeable and labile (I.e., directly reducible at pH 8) Cu In seawater at trace levels. Stripping polarographic or pseudopolarographlc determinations show that the Cu-en complex behaves reversibly In seawater, exchanging two electrons at the mercury drop electrode (HMDE). The role of chloride Ions In competitive reactions with en for copper during the stripping step was also studied. In seawater made 2 X 10'3 M In en, Cu(II) can be detected at the HMDE by differential pulse anodic stripping voltammetry (DPASV) at the 5 X 10"1°M level with a deposition time of 10 min. A new procedure for measuring pH 8 labile copper in seawater Is obtained by coupling DPASV with a medium alteration method. Addition of en at the end of the electrolysis increases peak height by more than twice by doubling the current yield per mole of Cu and by removing Interferences associated with the oxidation of Cu In Cl" media. This procedure facilitates the voltammetrlc study of Cu In seawater under natural conditions.

Copper Concentration and CuII Activity in San Diego Bay

“…The pCu of the samples was measured immediately with the Orion 94-29 electrode calibrated against Cu-ethylenediamine and Cu-glycine buffers prepared in artificial seawater [16,20]. The samples were then refrigerated and analyzed within two days according to a speciation scheme developed earlier [21]. For each sample, the labile and ethylenediamine (EN) exchangeable fractions were measured.…”

A voltammetric study of copper-ion binding to the cell surface of the marine alga

“…Total and labile copper were determined using ethylenediamine (EN) as reagent and matrix modifier respectively as previously described (Scarano et al, 1990). The use of EN improves the sensitivity by doubling the current yield per mole of eu and removes the interferences associated with the oxidation of eu in multi-ligand chloride media.…”

Copper complexation capacity in surface waters of the Venice Lagoon

“…The working electrode was a thin mercury film electrode (TMFE), the reference electrode was a Ag/AgCl electrode and a Pt-wire was used as the auxiliary electrode. Briefly, 10 mL samples were aliquoted in a Teflon™ cell and acidified to pH <2 by addition of 200 µL of Ultrex Grade HCl (Scarano et al, 1990). After first purging the sample for 6-8 min with ultrapure nitrogen, the…”