Abstract This article addresses the challenge of achieving ultra-high purity standards—"five-nines" (99.999%) or better—in precious metal recycling from electronic waste, where trace amounts of light element impurities (carbon, sulfur, oxygen, nitrogen) can critically impact material performance. Traditional analytical methods are inadequate for detecting contamination at parts-per-million or parts-per-billion levels, prompting the adoption of advanced combustion and inert-gas fusion techniques that rapidly measure impurities by heating samples in controlled atmospheres and detecting evolved gases. A case study using specialized analyzers demonstrated successful implementation and high-precision results. This rapid, non-destructive analytical approach enables accelerated quality assurance, provides definitive purity certification, supports high-throughput operations while preserving valuable material, ultimately making urban mining of precious metals from e-waste an economically viable component of the circular economy.
Michelle N. Sestak (Thu,) studied this question.