Determination of copper complexation in seawater using flow injection analysis with chemiluminescence detection

Flow injection analysis with chemiluminescence detection (FIA-CL) via the r eaction of copper with 1,10-phenanthroline was used for the determination o f copper complexation in seawater. A detection limit of 0.1 nM Cu in undilu ted seawater without sample preconcentration was obtained. Copper speciatio n was assessed by titrating natural seawater ligands with added copper. Thi s method was used to measure copper complexation throughout the water colum n in Monterey Bay, California. Two ligand classes were identified: a strong ligand (L-1), ranging in concentration from 1.3 to 3.1 nM, and a weaker li gand (L-2), ranging from 9.4 to 25.6 nM. The average conditional stability constant for the strong ligand was log K-1' 13.1+/-0.4 and for the weaker l igand log K-2' 9.4+/-0.6. These measurements are in good agreement with com plexation studies previously performed using established methods. This tech nique may eventually be adapted for in situ complexation measurements that can be used to monitor natural spatial and temporal variations in copper co mplexation, as well as coastal ecosystem responses to urban and industrial change. (C) 1998 Elsevier Science B.V. All rights reserved.