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Chemical Stability and Compatibility - Hydrofluoric acid (HF) and glass volumetric flasks

 
After microwave digestion of an ash sample using 1.5ml HF ( with 3.5ml HCl and 2 ml HNO3), can I use the borosilicate volumetric flask of 100ml to make up the sample for measurement by ICP-OES? I do not know if this concentration of HF will attack the flask. Also my standard prep requires a similar matrix, is this concentration of HF safe to use in the volumetric flask? My method also suggests adding 40ml of a 1.5% Boric acid solution, but the preparation of the Boric acid solution is given as 1.5 g boric acid powder to HF in a plastic flask....The person who wrote the procedure left the company before I came and I don't think this is right. Please advise, thank you!
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The presence of HF will attack your borosilicate glass volumetric flask, and the more HF that is present the greater the effect on the flask. If the solution is in the flask for only a few moments, the damage is likely to be almost negligible; the greater concern, however, is the leaching of contaminant elements such as Si, Al, B, etc. that could compromise your results. As for the boric acid solution you describe, it’s not clear what the exact preparation is. If the procedure is to add boric acid to a solution containing hydrofluoric acid then this will create fluoroboric acid, which can still attack glass, and is the likely reason that use of a plastic flask is described.

Posted: 08/30/18 23:22:01

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