Sodium Poroxide Fusion
The sample is fused at 700ºC with Sodium Peroxide. The fused material is dissolved in Hydrochloric acid, diluted with water and analysed by ICP-OES or ICP-MS. The fusions are typically carried out in Alumina crucibles, although Zirconium crucibles can be used if Aluminium is a required analyte.
All minerals are extracted using this technique, however it has the following disadvantages:
Some volatiles are lost due to the high temperatures of the fusion. The resulting digest must be additionally diluted to get the total salt level (Sodium Peroxide plus sample) to a level acceptable to the instruments. Consequently, detection limits are usually 10 times higher than those achieved by the acid digest techniques.
With all of the above procedures, difficulties may be experienced if certain element levels are very high in the sample. Lead and Barium for example may re-precipitate at high levels (over 1 or 2 percent) unless special precautions are taken. Communication between the laboratory and the sample supplier of the suspected presence of high levels of specific elements will enable the laboratory to provide appropriate modifications to analytical methods to ensure correct results are achieved.
Detection Limits by ICP-OES (Method Code : ICP104)
| Al (100 ppm) |  As (100 ppm) |
B (10 ppm) |
Ba (20 ppm) |
Ca (0.1%) |
| Co (20 ppm) | Cr (50 ppm) |
Cu (50 ppm) |
Fe (100 ppm) |
K (100 ppm) |
| Mg (100 ppm) | Mn (10 ppm) |
Mo (50 ppm) |
Ni (50 ppm) |
P (100 ppm) |
| Pb (50 ppm) | S (100 ppm) |
Sc (10 ppm) |
Si (100 ppm) |
Sr (100 ppm) |
| Ti (100 ppm) | V (50 ppm) |
Zn (20 ppm) |
Zr (10 ppm in Alumina Crucibles) |
|
Detection Limits by ICP-MS (Method Code : ICP304)
| Ag (5 ppm) | As (5 ppm) |
Ba (10 ppm) |
Be (10 ppm) |
Bi (2 ppm) |
| Cd (10 ppm) | Ce (0.5 ppm) |
Cs (1 ppm) |
Dy (0.5 ppm) |
Er (0.5 ppm) |
| Eu (0.2 ppm) | Ga (2 ppm) |
Gd (2 ppm) |
Ge (20 ppm) |
Ho (0.2 ppm) |
| In (0.2 ppm) | La (0.5 ppm) |
Li (1 ppm) |
Lu (0.2 ppm) |
Mo (5 ppm) |
| Nb (5 ppm) | Nd (0.5 ppm) |
Ni (20 ppm) |
Pr (0.2 ppm) |
Rb (0.2 ppm) |
| Re (1 ppm) | Sc (20 ppm) |
Sm (0.5 ppm) |
Sn (10 ppm) |
Sr (1 ppm) |
| Ta (0.5 ppm) | Tb (0.2 ppm) |
Th (0.5 ppm) |
Tl (2 ppm) |
Tm (0.2 ppm) |
| U (0.5 ppm) | W (5 ppm) |
Y (1 ppm) |
Yb (0.5 ppm) |
Zr (10 ppm) |