Evaluation on the use of cerium in the NBL Titrimetric Method
An alternative to potassium dichromate as titrant in the New Brunswick Laboratory Titrimetric Method for uranium analysis was sought since chromium in the waste makes disposal difficult. Substitution of a ceric-based titrant was statistically evaluated. Analysis of the data indicated statistically equivalent precisions for the two methods, but a significant overall bias of +0.035% for the ceric titrant procedure. The cause of the bias was investigated, alterations to the procedure were made, and a second statistical study was performed. This second study revealed no statistically significant bias, nor any analyst-to-analyst variation in the ceric titration procedure. A statistically significant day-to-day variation was detected, but this was physically small (0.01 5%) and was only detected because of the within-day precision of the method. The added mean and standard deviation of the %RD for a single measurement was found to be 0.031%. A comparison with quality control blind dichromate titration data again indicated similar overall precision. Effects of ten elements on the ceric titration`s performance was determined. Co, Ti, Cu, Ni, Na, Mg, Gd, Zn, Cd, and Cr in previous work at NBL these impurities did not interfere with the potassium dichromate titrant. This study indicated similar results for the ceric titrant, with the exception of Ti. All the elements (excluding Ti and Cr), caused no statistically significant bias in uranium measurements at levels of 10 mg impurity per 20-40 mg uranium. The presence of Ti was found to cause a bias of {minus}0.05%; this is attributed to the presence of sulfate ions, resulting in precipitation of titanium sulfate and occlusion of uranium. A negative bias of 0.012% was also statistically observed in the samples containing chromium impurities.
- Research Organization:
- USDOE New Brunswick Lab., Argonne, IL (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- OSTI ID:
- 62721
- Report Number(s):
- NBL-332; ON: DE95011952; NC: NONE
- Resource Relation:
- Other Information: PBD: Mar 1995
- Country of Publication:
- United States
- Language:
- English
Similar Records
Annual Progress Report for the Period July 1961 Through June 1962
Establishing a High-Precision Titrimetric Laboratory at Oak Ridge National Laboratory to Support the NBL Program Office’s Mission