Electrochemical determination of silver sols for sensor developments

Abstract

Characterisation of an electrochemical method for measuring silver sols (aqueous suspensions of nanometer-sized particles) is described. Such particles are receiving much attention by others as valuable components in the development of biosensing systems. The work was centred on the use of screen-printed three-electrode devices to measure the concentration of silver sols by a sequence of processes: (i) dissolution of the silver particles to form silver ions; (ii) accumulation of silver on the working electrode; and (iii) stripping of the accumulated silver. The silver sol concentration was related to the observed stripping peak (peak height or peak area). Carbon electrodes were used throughout and the influence of carbon type, electrode format/arrangement and dissolution potential were examined. A number of interesting observations were made and conclusions arrived at: (a) the arrangement of working, reference and counter electrodes was important and a preferred arrangement was indicated; (b) electrode material and/or format were important – but further work would be necessary to identify whether one or both factors were particularly important; (c) the choice of dissolution potential was crucial – and further work needs to be carried out to ensure that a sufficiently stable reference electrode can be arrived at; and (d) preliminary evidence is presented that indicates that silver contamination of the screen-printed silver electrodes was a limiting factor that needed to be corrected/mitigated in order to arrive at robust/reproducible measurement devices.