Dear Sir. Concerning your issue about the acid digestion of Ag and Sb for the ICP analysis. Ultra high-purity or equivalent acids must be used in the preparation of standards and for sample processing. Redistilled acids are recommended because of the high sensitivity of ICP-MS. Nitric acid at less than 2% (v/v) is necessary for ICP-MS to minimize damage to the interface and to minimize isobaric molecular-ion interferences with the analytes. Many more molecular-ion interferences are observed when hydrochloric and sulfuric acids are used (Refs. 3 and 4). The use of 1% (v/v) HCl is necessary for the stability of antimony and silver concentrations in the range of 50 - 500 µg/L. For concentrations greater than 500 µg/L silver, additional HCl will be needed. As a consequence, the accuracy of analytes that need significant chloride molecular-ion corrections (e.g., As and V) will degrade. For more details, I think the following below link may help you in your analysis:

https://www.epa.gov/sites/production/files/2015-12/documents/6020b.pdf

Thanks

Hi Nargess,

by using HCl (s. here https://clu-in.org/download/ert/1811-r30.pdf)

Regards Markus

Aqua Regia.

Dear Sir. Concerning your issue about the acid digestion of Ag and Sb for the ICP analysis. Ultra high-purity or equivalent acids must be used in the preparation of standards and for sample processing. Redistilled acids are recommended because of the high sensitivity of ICP-MS. Nitric acid at less than 2% (v/v) is necessary for ICP-MS to minimize damage to the interface and to minimize isobaric molecular-ion interferences with the analytes. Many more molecular-ion interferences are observed when hydrochloric and sulfuric acids are used (Refs. 3 and 4). The use of 1% (v/v) HCl is necessary for the stability of antimony and silver concentrations in the range of 50 - 500 µg/L. For concentrations greater than 500 µg/L silver, additional HCl will be needed. As a consequence, the accuracy of analytes that need significant chloride molecular-ion corrections (e.g., As and V) will degrade. For more details, I think the following below link may help you in your analysis:

https://www.epa.gov/sites/production/files/2015-12/documents/6020b.pdf

Thanks

Dr. Elgailani, Toner and Toner,

Many thanks for your perfect answers and valuable time.

I think Ag will precipitate by using HCl or Aqua Regia, doesn't it?

Isam gave a very detailed answer.

Yes i think it is possible. Ues the 5%HNO3 for this purpose. To maintain the stability of sb to use 1%HCl

Thank you very much for all the valuable comments.

I test the antimonite sample by once using HNO3+HCl (2:1) and once using Aqua Regia and heating. First the sample was perfectly turned into a clear yellow solution. But when I diluted them to 50cc with distilled water, both of them turned into a white insoluble deposit!

I guess it should be AgCl and/or antimonic acid (?).

How do you think?

Thank you.

P.S: I want to measure Sb and Ag by ICP-OES.

Use a mixture of acids. HNO3 + HCl, as mentioned above.

"As a consequence, the accuracy of analytes that need significant chloride molecular-ion corrections (e.g., As and V) will degrade." Absolutely! Had a boss once who thought the corrections fixed everything, but as Isam says, they don't. That's why we must avoid HCl unless necessary.