| Element(ppm max) | Grade FND-1 | Grade FND-2 | Grade FND-3 |
| Ta |
30 |
50 | 80 |
| O | 80 | 150 | 250 |
| N | 30 | 40 | 50 |
| C | 20 | 50 | 100 |
| H | 10 | 10 | 30 |
| Si | 30 | 50 | 50 |
| Fe | 20 | 30 | 50 |
| W | 20 | 30 | 30 |
| Mo | 10 | 20 | 30 |
| Ti | 10 | 20 | 30 |
| Cu | 10 | 20 | 20 |
| Cr | 10 | 20 | 20 |
| Ni | 20 | 20 | 30 |
|
Al |
20 | 20 | 30 |
