The analysis of solid sample can be performed using X-Ray fluorescence. The other method is to analyze the sample using SEM-EDS or EPMA, but it will give the concentrations in microregions, not the bulk sample.

The most trusted way to obtain bulk sample metal concentrations is to send it to certified lab (e.g. Bureau Veritas Minerals), where the sample will be prepared and analyzed. The method they use is tetraborate fusion with nitric acid leaching of the residue and the leachate is analyzed with ICP-ES/MS and XRF. However, if you wanna do the digestion yourself, the aqua regia is not really helpful, because it gives quasi-total amounts of metals present in the sample. Therefore, you will need to digest your sample in stronger acids (e.g. 4-acid method).

In case of organic acid leaching, all of methods used to analyze liquid samples have problems with interferences. In my opinion, the most suitable method to analyze Au and Cu in the leachate would be AAS or ICP-MS, or ICP-OES as a last resort.

1. Wet chemical analysis by ICP-MS/OES gives the most accurate metal content of e-waste for a wide range of metals and their concentration. Since liquid samples are required for ICP analysis e-waste must be dissolved prior to the analysis. Depending on e-waste various reagents are used for dissolving e-waste. Aqua regia is suitable for dissolving Precious metals, Cu, Ni, Co from PCBs where as e-waste containing rare earths are subjected to caustic soda roasting prior to dissolving in acid. Other techniques like XRF and EDS are also available, however they are comparatively less accurate.

2. An extra attachment that can purchased be from the supplier of ICP can enable it to determine metal content in metal solutions. Please check with the supplier.

Thank you very much for your kind answers.

Bartosz Mikoda, Can AAS analysis obtain how much metal contained in E-waste?

And I asked ICP supplier as Amit Anand mentioned, they have 'organic kits' for quantitative analysis of metal concentration in organic acid what can use with ICP-OES.

Thank you guys again,

The AAS analysis will capture only the dissolved metal in a solution. The concentration of a given metal is dependent on a lixiviant. For example, the 4-acid method would extract more metal than aqua regia.

Bartosz Mikoda Thank you, I will try it! Always good luck to you.

ICP-MS has been applied to the determination of over 60 elements in various matrices and it is the best way for Identification of metals particularly trace metals

By ICP - MS technique

Bartosz Mikoda Hi again, I would liked to prepare 4-acid solution what you suggested before.

Multi-acid digestion uses a combination of HCl (hydrochloric acid), HNO3 (nitric acid), HF (hydrofluoric acid) and HClO4 (perchloric acid).

Do i combine these acids in 1:1:1:1 ratio?

Please let me know a certain ratio of 4-acid solution.

Thank you very much!

Dear Bahram Hosseini Monjezi and Nadia Sadiq Majeed ,

Thanks for your comment. By the way, I heard that organic acid sample is difficult to analyze by ICP-MS because organic acid contains carbon. Carbon may result in critical effects on conditions of ICP-MS. Thus, the additional accessory should be necessary e.g., Oxygen gas.

Jong-Won Choi I never have used this method, but some authors write that they used 2:3:2:1 ratio of HCl:HNO3:HF:HClO4 (namely 10:15:10:5 ml for 500 mg sample, but sometimes more HF and HClO4 has to be used). However, HClO4 is used mainly for organic parts, which are lacking in PCBs for sure. Then, maybe 3-acid method would be suitable with ratio 3:1:1 HNO3:HCl:HF (or H2O2 instead of HF since PCBs are also lacking silicate minerals which HF is used for).

Bartosz Mikoda, Thank you for your great assistance!