Images of the WPCBs (prior to pulverisation) used in the preparation of the WPCB iodide leachate are shown in Figure . The WPCBs were originally 50 g in mass and 10 cm x 15 cm in size and their metal composition is shown in Table . Metal composition of the WPCBs used was determined by leaching 50 g of pulverised and homogenised WPCBs in aqua regia at a S/L ratio of 25 g/L, for 24 hrs, and then chemically analysing the leachate produced by ICP-OES. It is important to note that the WPCBs used in this study were unpopulated (not covered by a solder) ideal/model boards which were specifically designed for this project by Trax Interconnect. Au Selective Ion Exchange Extractant Membrane (Au-IEM). The Au-IEM used in the laboratory experiment was a heterogenous membrane comprised of 40 wt.% poly-vinyl-chloride (PVC) polymer-backbone and 60 wt.% Purogold S992 extractant carrier. This membrane composition was based on data provided by Křivčík et al. who suggested that extractant membranes with a 40/60 polymer-backbone/ extractant carrier ratio exhibit good selectivity, permselectivity, and conductivity . This is important considering that selectivity determines how well the Au-IEM separates Au ions from competing base metal (BM) impurity ions, permselectivity determines the efficiency (yield) in which the Au-IEM will transport Au ions through its body, and conductivity determines the rate at which Au ions will be transported through the Au-IEM body.