Determination of trace elements in seawater by neutron activation analysis and electrochemical separation

Abstract

The combination of neutron activation analysis and electrolysis at a constant, controlled potential has proved itself to be a useful multielement method for the determination of 28 elements in seawater. After freeze-drying and irradiation, the samples are dissolved and electrolyzed for 1 h. The radioactive species deposited on the mercury cathode allow determination of 14 elements (Ag, As, Au, Cd, Co, Cr, Fe, Ga, Hg, La, Mo, Sb, Se, Zn). Another 14 elements (Ba, Br, Ca, Ce, Cs, Eu, Na, Rb, Sc, Sm, Sr, Th, U, Yb) are quantitatively determined by measuring the activities in the residual solution. To obtain a reproducible electrolysis, radioactive tracers have been used to study the decrease of element concentrations in solution as a function of time of electrolysis, the influence of the initial element concentration on the rate constant k, the effect of cathode material and of the pH in the solution. 4 figures, 4 tables.