Cell Suspension as a Model System for Electrochemical Analysis

Cell suspensions of marine phytoplankton Dunaliella tertiolecta in 0.1 M NaCl solution are proposed as a suitable model monodispersed system (particle diameter 6-10 μm) for the calibration of electrochemical response in natural aquatic samples containing organic surface-active particles. The electrochemical analysis is performed by direct recording of chronoamperometric curves of oxygen reduction in suspensions using a fast dropping mercury electrode. The electrode acts as adhesion sensor. The adhesion of individual surface-active particles suspended in natural seawater, analogously to Dunaliella tertiolecta cells in model suspensions, results in well resolved attachment signals in amperometric curves. The calibration curve presents dependence of attachment frequency on cell densities in the concentration range 106 to 2.5 x 107 particles L-1 and it can be used for the determination of particle abundance in a seawater sample. The advantage of the electrochemical approach over more conventional methodologies for particle analysis is discussed.