Digestion of Insoluble Fluorides in Geochemical Samples by Ammonium Fluoride

Abstract

The ability of ammonium fluoride attacking insoluble fluorides was studied. Ammonium fluoride was used to digest some geochemical certified reference materials instead of hydrofluoric acid. Inductively coupled plasma optical emission spectrometry and inductively coupled plasma mass spectrometry were employed to determined major, minor, and trace elements, respectively. By testing CRMs and a large number of real samples, it was determined that the effects on those elements, which easily formed insoluble fluorides, were better by ammonium fluoride than by hydrofluoric acid. Furthermore, it was more secure for operators using ammonium fluoride than hydrofluoric acid. A possible mechanism was also proposed.

Keywords:

• Ammonium fluoride
• ICP-AES
• ICP-MS
• Insoluble fluorides
• XRF

Notes

Note. The times of determination is five; the unit is % to the elements noted “*”.