Good morning Prof. Mnculwane,

I am an Italian researcher who is working on the recovery of REEs and other critical elements from granites.

I’m writing to you to get more information about the procedure described in your work (Rare Earth Elements Determination by Inductively Coupled Plasma Mass Spectrometry after Alkaline Fusion Preparation, Analytica, 2022).

I read with great interest your paper as my aim was to use alkaline fusion with Na peroxide and NaOH to replace the procedure that I usually use (with Li metaborate). I need to change my procedure as I am also interested to analyse lithium!

I tried to apply the procedure that you described in your paper, but I don’t know why the fusion is not complete. After fusion at 600 °C, inside the crucible I get a material only partially melted that I cannot recover, if not partially. Moreover, after the addition of water, tartaric acid and nitric acid inside to crucible it is formed a sort of gel and material partially melted that I can't dissolve. Can you tell me why this happens?

Moreover, I ask you some questions:

- I use pellets of sodium peroxide. Should I pulverize it?

- Why did you place the crucibles into 250 mL beacker?

- I don’t understand this phrase “and thereafter placed into 250 mL beackers containing 10 mL ultrapure water plus tartaric acid”. I understood that 10 mL of ultrapure water and the tartaric acid must be placed inside the crucible; after that I must add 5 ml of nitric acid. Is this correct?

- How do you do leaching with nitric acid? On a magnetic stirrer placing a magnet inside the crucible? Alternatively?

- The crucibles must be mandatory of zirconium or even of another material (i.e. ceramic or platinum?)

- The optimal temperature is 600 °C? Or can I also melt samples at a higher temperature?

Finally I ask you: could I have your procedure with all the steps described in more detail?

I hope to hear from you soon.

Thanks and sorry for disturbing.

Best regards

Dr. Francesco Nannoni