Nitric acid AsO, SbO, and TiO respectively. Some precious metals, such as pure gold and platinum-group metals do not react with nitric acid, though pure gold does react with "aqua regia", a mixture of concentrated nitric acid and hydrochloric acid. However, some less noble metals (Ag, Cu, ...) present in some gold alloys relatively poor in gold such as colored gold can be easily oxidized and dissolved by nitric acid, leading to colour changes of the gold-alloy surface. Nitric acid is used as a cheap means in jewelry shops to quickly spot low-gold alloys (< 14 carats) and to rapidly assess the
Simultaneously extracted metals and Acid-volatile sulfide Simultaneously extracted metals and Acid-volatile sulfide Simultaneously extracted metals/Acid-volatile sulfide (SEM-AVS) is an approach used in the field of aquatic toxicology to assess the potential for metal ions found in sediment to cause toxic effects in organisms dwelling in the sediment. In this approach, the amounts of several heavy metals in a sediment sample are measured in a laboratory; at the same time, the amount of acid-volatile sulfide (sulfide which can be liberated from the sediment by treatment with hydrochloric acid) is determined. Based on the chemical interactions between heavy metals (SEM) and acid-volatile sulfide (AVS), the concentrations of these