Determination of Gold in e-Waste Dust Samples and Geological Matrices by ICP-MS after Extraction by an HClO4-HBr-HI-Aqua Regia Mixture
Abstract
This study describes two methods (Procedures-1 and -2) for the direct extraction of Au by an inorganic acid mixture (HClO4-HBr-HI-aqua regia) from complex sample matrices. Standard PTFE jars at 200 degrees C were used to decompose test portions of 0.5-1 g, with subsequent precise and accurate analysis by ICP-MS without any other preconcentration or separation.
Procedure-1 decomposed samples effectively without the necessity of leaching with HF and was developed for dust samples from e-waste (electronic waste) processing; however, testing on geological reference materials showed very good results. The analyses of replicate decompositions (n = 5) from both procedures yielded very good precision (< 5% RSD) for most of the reference materials.
The accuracy achieved was better than +/- 10%, with the exception of NIST SRM 2782 data from Procedure-1. Two unknown samples of dust from e-waste processing (P-1 and VM-1) exhibited elevated concentrations of Au (21.31-61.64 mu g g(-1)) with precision better than 10% (n = 5).
The proposed techniques are simple, sensitive and sparing in the use of chemicals, and are designed for a variety of e-waste dust samples. No significant influences were observed for the predicted spectral interferences on mass Au-197.