 |
| U.S. Geological Survey Open-File Report 2004-1350 |
Table 2.2 - Method for ultratrace elemental analyses
A 0.5 g sample is digested in aqua regia at 90°C in a microprocessor controlled digestion box for 2 hours. The solution is diluted and analyzed by ICP/MS using a Perkin Elmer SCIEX ELAN 6100. International certified reference materials USGS GXR-1, GXR-2, GXR-4 and GXR-6 are analyzed at the beginning and end of each batch of samples. Internal control standards are analyzed every 10 samples and a duplicate is run for every 10 samples.
| Code Ultratrace-1 Elements and Detection Limits (ppm) |
| Element |
Detection Limit |
Upper Limit |
| Au* |
0.2 ppb |
20,000 ppb |
| Ag* |
0.05 |
200 |
| Cu |
0.1 |
10,000 |
| Cd |
0.1 |
200 |
| Mn* |
1 |
10,000 |
| Mo |
0.01 |
1,000 |
| Pb* |
0.01 |
1,000 |
| Ni* |
0.1 |
5,000 |
| Zn* |
0.1 |
10,000 |
| As* |
0.1 |
10,000 |
| B* |
1 |
5,000 |
| Ba* |
0.5 |
6,000 |
| Sb |
0.02 |
500 |
| W* |
0.2 |
200 |
| Al* |
0.01% |
10% |
| Be* |
0.1 |
1,000 |
| Bi |
0.02 |
2,000 |
| Ca* |
0.01% |
50% |
| Ce* |
0.01 |
200 |
| Co |
0.1 |
500 |
| Cr* |
0.5 |
500 |
| Cs* |
0.1 |
100 |
| Eu* |
0.1 |
100 |
| Fe* |
0.01% |
50% |
| Ga* |
0.02 |
500 |
| Ge* |
0.1 |
500 |
| Hf* |
0.1 |
500 |
| In |
0.02 |
100 |
| K* |
0.01% |
5 |
| La* |
0.5 |
200 |
| Li |
0.5 |
1,000 |
| Lu* |
0.1 |
100 |
| Mg* |
0.01% |
10% |
| Na* |
0.001% |
1% |
| Nb* |
0.1 |
500 |
| Nd* |
0.1 |
200 |
| Rb* |
0.1 |
500 |
| Re |
0.001 |
100 |
| Se |
0.1 |
1,000 |
| Sm* |
0.1 |
100 |
| Sn* |
0.05 |
200 |
| Sr* |
0.5 |
1,000 |
| Ta* |
0.05 |
50 |
| Tb* |
0.1 |
100 |
| Te |
0.02 |
500 |
| Th* |
0.1 |
200 |
| Tl* |
0.02 |
500 |
| U* |
0.1 |
200 |
| V* |
1 |
1,000 |
| Y* |
0.1 |
500 |
| Yb* |
0.1 |
200 |
| Zr* |
0.1 |
5,000 |
0.5 g of sample is digested with aqua regia (0.5 ml H20, 0.6 ml concentrated HNO3 and 1.8 ml concentrated HCl) for 2 hours at 95°C. Sample is cooled then diluted to 10 ml with deionized water and homogenized. The samples are then analyzed using a Perkin Elmer OPTIMA 3000 Radial ICP for the 37 element suite. A matrix standard and blank are run every 13 samples.
A series of USGS-geochemical standards are used as controls. This digestion is near total for base metals however will only be partial for silicates and oxides.
| Code 1E2 Elements and Detection Limits (ppm) |
| Element |
Detection Limit |
Upper Limit |
| Ag* |
0.1 |
100 |
| Al* |
0.01% |
|
| As* |
3 |
|
| B* |
5 |
|
| Ba* |
1 |
|
| Be* |
1 |
|
| Bi* |
2 |
|
| Ca* |
0.01% |
|
| Cd |
0.2 |
2,000 |
| Co* |
1 |
|
| Cr* |
2 |
|
| Cu |
1 |
10,000 |
| Fe* |
0.01% |
|
| Hg |
1 |
|
| K* |
0.01% |
|
| La* |
1 |
|
| Mg* |
0.01% |
|
| Mn* |
1 |
10,000 |
| Mo* |
2 |
10,000 |
| Na* |
0.001% |
|
| Ni* |
1 |
10,000 |
| P* |
0.001% |
|
| Pb* |
2 |
5,000 |
| S* |
0.001% |
20% |
| Sb* |
5 |
|
| Sc* |
0.1 |
|
| Sn* |
5 |
|
| Sr* |
1 |
|
| Te* |
1 |
|
| Ti* |
0.01% |
|
| Tl* |
2 |
|
| V* |
1 |
|
| W* |
1 |
|
| Y* |
1 |
|
| Zn* |
1 |
10,000 |
| Zr* |
1 |
|
