AgNO3 was purchased from Sigma-Aldrich ( Ireland ). Gum Arabic was purchased from both Sigma Aldrich and from Amazon.co.uk. The commercial mineral water was purchased from local shopping market. The real river sample was collected from the local river Lee, Cork, Ireland. Samples were prepared using ultra-pure Mili-Q water (18.2 MΩ•cm -1 , Mili-Q). Electrochemical depositions were undertaken with an Ivium pocketSTAT handheld potentiostat operating under computer control.