Development and application of reference and routine analytical methods providing SI-traceable results for the determination of technology-critical elements in PCB from WEEE

Abstract

The recovery and reprocessing of Technology-Critical Elements (TCE) present in printed circuit boards (PCB) from electrical and electronic waste is essential both for recycling valuable materials subject to supply risk and for reducing the environmental impact. Although the quantitative knowledge of TCE amounts in end of life PCB plays a key role, there are neither matrix certified reference materials nor harmonized analytical methods available to establish the traceability of the results to the International System of Units. To fill these gaps, we developed and applied reference analytical methods based on ICP-MS standard addition calibrations and INAA k₀- and relative calibrations suitable to certify reference materials. In addition, we developed and tested analytical methods based on more commonly used ICP-MS external standard calibrations to provide routine methods. Sample preparation methods and measurement procedures accounting for issues due to the high heterogeneity of the PCB material and interferences arising from the matrix components are described. TCE mass fraction results obtained with reference and routine methods are compared to highlight possible discrepancies.