248 samples were analyzed for copper, zinc, cobalt, nickel, cadmium and chromium using Inductively Coupled Plasma. 299 samples were analyzed for gold, silver, lead, antimony and molybdenum using Atomic Absorption Spectroscopy. 298 samples were analyzed for arsenic using Atomic Absorption Spectroscopy. 247 samples were analyzed for iron and manganese using Inductively Coupled Plasma. The published analytical methods are ambiguous but to the best of our knowledge: 297 samples were analyzed for tin using Atomic Absorption after aqua regia digestion and hydride generation. 297 samples were analyzed for tungsten using colorimetric methods. Some results in this publication appear to be incorrect or typos. Obvious mistakes have been fixed [...]
