Table 7.
Absolute isotopic ratios for the three standard samples
| 204Pb/206Pb | 207Pb/206Pb | 208Pb/206Pb | |
|---|---|---|---|
| Common Lead (SRM 981) | 0.059042 | 0.91464 | 2.1681 |
| Overall limit of errora | ±0.000037 | ±0.00033 | ±0.0008 |
| Uncertainty Components: 95% confidence limits on ratio determination (minimum = 0.00002) | ±0.000020 | ±0.00007 | ±0.0002 |
| Bounds due to possible systematic error in chemical analyses | ±0.000005 | ±0.00007 | ±0.0002 |
| Bounds due to possible systematic error in correction factor (including errors in separated isotopes) | ±0.000012 | ±0.00019 | ±0.0004 |
| Equal-Atom Lead (SRM 982) | 0.027219 | 0.46707 | 1.00016 |
| Overall limit of error | ±0.000027 | ±0.00020 | ±0.00036 |
| Uncertainty Components: 95% confidence limits on ratio determination (minimum = 0.00002) | ±0.000020 | ±0.00006 | ± 0.00007 |
| Bounds due to possible systematic error in chemical analyses | ±0.000002 | ±0.00004 | ±0.00008 |
| Bounds due to possible systematic error in correction factor (including errors in separated isotopes) | ±0.000005 | ±0.00010 | ±0.00021 |
| Radiogenic Lead (SRM 983) | 0.000371 | 0.071201 | 0.013619 |
| Overall limit of error | ±0.000020 | ±0.000040 | ±0.000024 |
| Uncertainty Components: 95% confidence limits on ratio determination (minimum =0.00002) | ±0.000020 | ±0.000020 | ±0.000020 |
| Bounds due to possible systematic error in chemical analyses | ±0.000000 | ±0.000006 | ±0.000001 |
| Bounds due to possible systematic error in correction factor (including errors in separated isotopes) | ±0.000000 | ±0.000014 | ±0.000003 |
a
The overall limit of error is the sum of the 95 percent confidence limits for the ratio determinations and the terms covering effects of known sources of possible systematic error.