Simultaneous quantification of trace gold and platinum in copper alloys recycled from printed circuit boards using SPE coupled with ICP-AES
摘要
Copper (Cu) alloys recycled from printed circuit boards represent an important secondary source of precious metals (PMs), including gold (Au) and platinum (Pt). However, the complex composition of these alloys, particularly the high Cu content relative to PMs, poses significant analytical challenges for the accurate quantification of trace PMs. In this study, a reliable and selective method was developed by coupling solid phase extraction (SPE) with inductively coupled plasma atomic emission spectroscopy (ICP-AES) for the determination of Au and Pt in Cu-rich matrices. The adsorption and elution behavior of a strongly basic (AG1-X8) and a weakly basic (Diaion WA30) anion exchange resin were systematically investigated to optimize the separation of both metals. Both resins exhibited quantitative adsorption of Au and Pt in 0.1 mol L−1 HCl, with negligible Cu uptake. Desorption with 1 mol L−1 thiourea in 0.5 mol L−1 HNO3 efficiently recovered target PMs from metal-loaded resins, enabling their accurate isolation and quantification. Resin reusability was confirmed over multiple adsorption–desorption cycles following sequential washing with Milli-Q water (MQW), 0.75 mol L−1 NaOH, and MQW. A robust digestion protocol employing aqua regia, HF, H2SO4, and H3PO4 was established for the dissolution of Cu alloy and oxide samples, and the adsorption performance of the resin in H2SO4 medium was evaluated for the first time. The method achieved detection limits of 0.15–0.73 µg g−1 for Au and 0.06–0.30 µg g−1 for Pt, demonstrating its suitability for the quantitative determination of sub-µg g−1 levels of PMs in recycled Cu alloys and other Cu-rich secondary resources.