Cell suspension as a model system for electrochemical analysis

Cell suspensions of marine phytoplankton Dunaliella tertiolecta in 0.1 M Na Cl solution are proposed as a suitable model monodispersed system (particle diameter 6-10 mu m) for the calibration of electrochemical response in nat ural aquatic samples containing organic surface-active particles. The elect rochemical analysis is performed by direct recording of chronoamperometric curves of oxygen reduction in suspensions using a fast dropping mercury ele ctrode. The electrode acts as adhesion sensor. The adhesion of individual s urface-active particles suspended in natural seawater, analogously to Dunal iella tertiolecta cells in model suspensions, results in well resolved atta chment signals in amperometric curves. The calibration curve presents depen dence of attachment frequency on cell densities in the concentration range 10(6) to 2.5 x 10(7) particles L-1 and it can be used for the determination of particle abundance in a seawater sample. The advantage of the electroch emical approach over more conventional methodologies for particle analysis is discussed.