Table 5.
231Pa reference material uncertainty budget for amount of 231Pa contained in each unit
| Uncertainty component | Description | Assessment type | Ui % |
|---|---|---|---|
| b231Pa | Measurement repeatability; standard uncertainty of 5 independent measurements for 231Pa molality of RM solution. | A | 0.032 |
| b233Pa | Measurement repeatability; standard uncertainty of 8 independent measurements for 233Pa molality of S solution. | A | 0.023 |
| bC112-A | IDMS tracer; standard uncertainty for uranium molality of diluted CRM 112-A solution used as U reverse-spike. | B | 0.090 |
| Decay | Decay correction; uncertainties associated with the 233Pa half-life and the interval between initial 233Pa purification and IDMS measurements. | B | 0.035 |
| Efficiency | Transmission efficiency; uncertainty of correction factor to compensate for differing mass spectrometer transmission efficiencies between uranium and protactinium during IDMS measurements. | B | 0.030 |
| MIDMS | Aliquot mass; uncertainty component associated with mass measurements of solution aliquots for IDMS. | B | 0.085 |
| Munit | Unit Unit mass; uncertainty component encompassing the maximum difference in the mass of dispensed solution aliquots and potential evaporative loss during dispensing. | B | 0.027 |
| MassSpec | Mass Mass spectrometry; estimated uncertainty associated with mass spectrometry including potential differences in mass fractionation of protactinium and uranium in MC-ICP-MS, blank corrections, background corrections, and collector efficiencies. | B | 0.086 |
| RU010 | CRM U010; standard uncertainty of n(235U)/n(238U) ratio for CRM used to calibrate the mass spectrometer. | B | 0.051 |
| Remainder | Remainder correction; estimated uncertainty for 233U measurements resulting from the proportion of 233Pa remaining in IDMS samples after 10 half-lives. | B | 0.008 |
| Relative combined standard uncertainty | 0.173% | ||
| Relative expanded uncertainty (k = 2) | 0.35% |
Assessment Type A denotes evaluation by statistical methods and Type B denotes evaluation by other methods. ui % is the percent relative standard uncertainty for the indicated uncertainty component. The uncertainty model presented in this table was calculated using the GUM Workbench software (Metrodata GmbH, Weil am Rhein, Germany)