Leaching Conditions for the Determination of Mobile Forms of Copper in Deep-penetrating Geochemical Samples and Its Preliminary Application

Deep-penetrating geochemistry is one of the exploration techniques to detect elemental information contained in the surface soils and transported through the covering of the concealed deposit. The selective leaching of mobile forms of elements is one of the most popular techniques. Since the contents of mobile forms of elements are always at the trace level, valuable information is easily concealed by the analytical errors caused from the complex leaching and determination procedures. At present, research on the leaching conditions is limited, and the degree of standardization of methods is poor. Experiments have been conducted for leaching conditions of determination for mobile forms of copper in deep-penetrating geochemical samples and are described here. The analytical parameters include solid-liquid mixing ratio, extraction time, pH, solid-liquid separation method and extraction temperature, as well as the determination method for extraction solution. The copper in leached solution was determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) with detection limit of 0.03 μg/g and RSD of 4.95%-7.39%. The method was simple and highly accurate. The method was applied in one buried Cu-Ni deposit in Henan Province and the results were obtained from the contents of total Cu and mobile Cu, showing that the delineated anomalies were consistent with the actual ore bodies.