THE USE OF ULTRASOUND IN THE ENHANCEMENT OF THE DEPOSITION AND DETECTION OF METALS IN ANODIC-STRIPPING VOLTAMMETRY

The fast electrochemical deposition of both mercury and amalgam films, a crucial step in analytical anodic stripping voltammetry, is demonst rated to occur in the presence of power ultrasound emitted from an imm ersion horn probe which was placed opposite the working electrode in a conventional three electrode cell. Due to considerably enhanced mass transport the rate of deposition is strongly increased compared to 'si lent' conditions. The total amount of mercury adhering to a glassy car bon electrode surface, however, is limited to a 'thin film' of microsc opically small droplets of mercury as shown by atomic force microscopy and voltammetry. Due to surface forces induced by ultrasound, abrasio n of some of the deposit occurs and after a certain period of time the parallel electro-deposition and abrasion processes reach a 'steady st ate'. The deposition of mercury in the presence of Pb2+ or Cu2+ result s in the formation of an amalgam and well-defined, very sharp 'strippi ng' responses for the oxidation process of the corresponding amalgam w ere detected. The merit of insonation in analytical electrode preconce ntration techniques is discussed.