| Electrocorrosion and spark ablation are described for rapid dissolution of metals in aqueous solution. When current is applied between two metal samples in de-ionized water at close proximity (0.5 mm), spark ablation occurs in a discrete area. Low-powered spark ablation was characterized using rates of ablation of various metal samples, demonstrating similar ablation rates for all metals, ranging from 20 mug s-1 to 60 mug s -1 over a period of 60 to 120 s. Low-powered spark ablation was also used as a method of Au analysis with experiments focusing on methodology and quantification of Cu and Ag in Au bullion reference material (BRM-1, BRM-2, BRM-3) from the Royal Canadian Mint. A method for dissolving Ag in gold samples was developed as an alternative to dissolution by aqua regia. Experimental results demonstrated that HNO3 was sufficient to dissolve the small aliquots of ablated metal, without matrix interferences using GFAAS.; Electrocorrosion utilises a conductive solution to carry charge, preventing spark formation.; Electrocorrosion of the metal surface appeared to be less damaging in appearance, indicating a less heterogeneously sampled surface. Energy dispersive x-ray fluorescence (ED-XRF) spectra of the spark-ablated surfaces indicated some elemental variability when high-powered spark ablation was used but not for low-powered spark ablation or electrocorrosion. (Abstract shortened by UMI.)... |
