this is only partly true. It is correct that HNO3 and NH4F separately are probably safer to handle but since HNO3 is a much stronger acid than HF, upon mixing the two you basically end up with a solution of NH4NO3 in HF and it doesn't take heating for that to happen. The advantage is therefore that you don't have a bottle of HF sitting around in your lab, but you are still creating it, albeit out of less harmful ingredients, and that is what gives the mixture its reactive properties. Once the two are mixed, the hazard and your precautions should be the same.
"[...] more than half the banana genome is shared with humans (a fact more
evident among some of my acquaintances than others)" - Sir Robert May
Dr. Johan Schijf
Assistant Professor, Aquatic Environmental Geochemistry
UMCES/Chesapeake Biological Laboratory
P.O. Box 38, 1 Williams Street
Solomons, MD 20688-0038
Tel. (410) 326-7387 (office) 7392 (lab)
Fax (410) 326-7341
e-mail: [log in to unmask] "Ph. De Raeve" <[log in to unmask]>:
> Dear HF users,
> I have been told by a microwave digestion apparatus manufacturer that
> digestion involving HF may be conveniently replaced by NH4F + HNO3.
> According to him, NH4F is much safer than HF (doesn't go through the
> skin !) and when heated in presence of acid, it generates HF in the
> closed vessel, ensuring safe digestion of siliceous compounds
> Does anybody have experience with it ?
> Is it as efficient as HF ?
> Philippe De Raeve
> Quality Assistance SA
> Technoparc de thudinie,1
> 6536 Donstiennes