<Original Paper>The Effect of Acid Concentration on the Emission Intensity of Transition Metal Lines in ICP-AES

In order to obtain reliable results by the technique of Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES), it is imperative to avoid or correct for interferences caused by the matrix of the solution samples. Differences in the acid concentration between the samples and the standards can significantly affect the analytical results. This effect has been investigated by analyzing several series of solution samples. The increase in the acid concentration is obviously accompanied by an increase in the viscosity, resulting in an initial decrease of the analytical signal. Further increasing the acid concentration, however, brings about a positive effect, which is largely enhanced by applying higher HCl concentrations in the washing solution and is efficiently reduced by purging the solution feeding line of the system. The positive effect is presumably related to the enhancement of excitation. This interpretation is suggested by the comparison of results obtained by two different instruments and different kinds of acid in the samples. The obtained relative intensity functions are suitable for the mathematical correction of matrix-induced interferences, provided the conditions of washing are standardized

Reduction of Copper Chloride with Hydrogen

Investigations have been carried out to establish the practicable working conditions of reducing unhydrous copper chloride material with hydrogen gas. The reduction process is made especially difficult by the low melting points and the high vapor pressures of the chloride material. The results of a comprehensive thermodynamic study revealed the probable reactions in the Cu-Cl-H system and pointed out the feasibility of the direct reduction of CuCl_2 in two consecutive operational steps. In order to find out the practical reduction rates and effective recovery levels, the process was tested at different temperatures. The first step of reduction, which results in the conversion of CuCl_2 to CuCl, is readily executable at temperatures slightly below the CuCl-CuCl_2 eutectic point with no evaporative losses. The second step of the reduction procedure, which results in the metallic product, requires higher temperatures, though safely below the melting point of CuCl. Kinetic analysis of the critical second step provided an activation energy of 138kJ mol^, which compared reasonably well with the scarcely available literature references, and could be interpreted in terms of a chemical reaction dominated mixed mechanism