Preparation and characterization of “exhausted electrowinning electrolyte” reference material

The number of available reference materials of complex matrices is continuously growing but it is still far from ideal. There are too many different matrices which are of interest for too many different analytes. The certified reference materials are expensive and are intended for the validation of methods or for the assurance of traceability of the analytical result. However, many determinations are carried out on a daily basis and the quality control for these determinations requires the use of reference materials, although not certified but laboratory reference materials. These materials are not certified but must be homogeneous and stable with respect to the concentration of the analytes of interest and they must have a similar matrix compared to the samples to be analysed, in order to be able to perform the quality control of the analytical determinations. The reference material herein presented is an exhausted electrowinning electrolyte from a local copper producing company. The analytical determination of the metals in the solution was performed using ICP-AES with a multivariate calibration procedure. The analytes are the following : As, Ca, Cu, Fe, Na, Ni, Sb and Zn