234U and 230Th determination by FIA-ICP-MS and application to uranium-series disequilibrium in marine samples.
A 234U and 230Th determination method based on an extraction chromatographic separation on a flow injection system coupled to a quadruple ICP-MS was developed. Two-milliliter UTEVA (Eichrom Co.) cartridges were applied as separation tool and 236U and 229Th as spikes. Loading and washing steps were carried out in 3 M HNO3 solution and 0.05 M ammonium oxalate applied to elute both uranium and thorium. The method was applied initially to the IAEA-327 soil reference sample and NIST SRM 4357 ocean sediment reference material, with the obtained 234U and 230Th concentrations in agreement with the reference levels. Samples from a deep-sea sediment core (2450 m water depth) were analyzed and based on 230Th/234U dating, a mean sedimentation rate of 3.3 cm ky(-1) was calculated. Samples from two sediment layers were also dated by 14C-AMS and the observed ages agree with the 230Th/234U results.
Instituto de Radioproteção e Dosimetria, Comissão de Energia Nuclear, Caixa Postal 37750, Barra da Tijuca, CEP 22643-970, Rio de Janeiro, RJ, Brazil.
Maria Luiza D P
ML
Godoy
José Marcus
JM
Godoy
Renato
R
Kowsmann
Guaciara M
GM
Dos Santos
Rosana
R
Petinatti da Cruz
D019015:Geologic Sediments / Q000737:chemistry*; D012015:Reference Standards; D012623:Seawater / Q000737:chemistry*; D013910:Thorium / Q000032:analysis*; D014501:Uranium / Q000032:analysis*; D014875:Water Pollutants, Radioactive / Q000032:analysis*
D014875:Water Pollutants, Radioactive; D014501:Uranium; D013910:Thorium