In order to measure the amount of Li in the rocks, 0.5 g of homogenized specimen powder (50 – 100 µm) were digested with 10.5 ml of 36 % HCL and 3.5 ml of 96 % HNO3 and heated for hours at 95°C. After cooling, 35 ml of ultra-pure water was added and filtered with a pleated filter. The filtrate was exactly filled up to 50 ml. The measurements were conducted using ICP-AES.
After the analysis, I got 10 - 30 ppm Li.
However, due to the big amount of acid residue (~95 %) I am wondering how much Li has remained in threacid residue??
Can Li be leached from glass or the silicate solely or does it dissolve together with the silica phases?
Thank you for your comments!
Why did you use aqua regia here? The oxidizing HNO3 is not an advantage for dissolving silicates. Cold solutions of HCl or H2SO4 would have had the same effect on volcanic glass.
Volcanic glass and basalts do not dissolve completely in strong mineral acids such as HCl, HNO3 and H2SO4. You can not rule out that part of lithium remains in filter after all. Only hydrofluoric acid (suffices a cold concentrated solution) dissolves silicates completely.
Thanks for your quick response Vadim Verlotski. I did not conduct the analysis by myself. I just have to deal with the consequences now. I am looking for the primary li source of the ignimbrite. Therefore, I am trying to roughly estimate the portion of dissolved Li.
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