Frequently Asked Questions - Neutralizing HF with triethanolamine

Dea sirs, Thank you for the great online guides and research papers. They are extremely informative. In part 6 of the ICP Operations Guide, Dr. Paul Gaines mentions the use of triethanolamine to neutralize HF. Can you or anybody else provide more detail? For example, how much TEOA should one use after digestion with HF/HNO3? Also, what is the addition of H4EDTA for and is it necessary? Thank you for any assistance.
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We would recommend neutralizing on a 1:1 molar basis, where concentrated HF is 28.8 molar (M) and triethanolamine (TEOA or TEA) is ~6.5 M.  It would therefore take about a 5% solution of TEA to neutralize ~1% HF.  You want the TEA to be in slight excess or just bring the pH up to 7-8. The use of EDTA provides greater complexation capacity and may not be necessary; we’d recommend using TEA to begin with and evaluating the results accordingly.

Posted: 08/30/18 21:06:01

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