POLAROGRAPHY OF MARINE PARTICLES - A MODEL STUDY

A simple polarographic method for direct measurement of surface active constituents of seawater was used to investigate the effect of variab le levels of dissolved surfactants on the detection of attachment sign als of surface active particles at the artificial interface. A mixture of dextran solutions and dispersion of insoluble squalene droplets si mulates electrochemical signals in natural samples and allows predicti on of the behaviour of natural organic particles. For the same distrib ution of particles in the aqueous dispersion, attachment signals frequ ency decreases exponentially with an increasing bulk. concentration of dissolved molecules. Attachment rate of particles at the dropping mer cury electrode (DME) depends on the extent of surface coverage with ad sorbed molecules (theta). At full coverage of the electrode, no partic le attachment signals can be detected. The actual distribution of surf ace active particles can be determined by direct measurement of attach ment signals when theta < 0.5, which is the case of the majority of se awater samples. For theta < 0.5, dilution with organic free electrolyt e and/or sampling within the initial part of the DME life-time should be used.