Purogold S992 has a macroporous structure and a styrenic backbone which is cross-linked with divinylbenzene (DVB). This means that it contains a network of pores within a gel matrix. Light is scattered by the pores, making the Purogold S992 extractant appear opaque. Proprietary functional groups that are attached to the backbone and located throughout the Purogold S992 extractant interact with Au ions in solution. The rate of reaction (kinetics) between Au ions in solution and the Purogold S992 extractant is controlled by the rate of ion diffusion through the thin film of H2O surrounding each individual bead of the Purogold S992 extractant (film diffusion) and through each bead of the Purogold S992 extractant itself (particle diffusion). In a dilute solution/ during the adsorption phase, the rate of film diffusion is slower than the rate of particle diffusion. However, during the subsequent stripping/ elution phase, the rate of film diffusion is faster than the rate of particle diffusion. It is important to note that in the present study, resin beads of Purogold S992 are suspended within a PVC matrix. Hence, a PVC layer is present over the surface of each individual S992 resin bead in the Au-IEM employed. This PVC layer increases the diffusion path length of ions, and as a result, may interfere with and reduce the rate of ion diffusion, since ions must travel through the outer PVC later before they can interact with the S992 resin beads and their outer H2O film. Furthermore, it is possible that when the S992 resin beads were mixed in PVC, their outer H2O film may have been damaged, thus resulting in further interference and reduction of ion diffusion rate.