Table 6 Quantity descriptions of the model equation for the GUM workbench. Equation is taken from Bièvre De and Peiser (1997)

C_USample

mol U/g

Mol U/g of solution in the unknown sample (taken from the certificate value of NBL and D&G)

R_58mix

at/at

²³⁵U/²³⁸U ratio in the mixture (spiked sample) (calculated from the assigned masses)

R_58spike

at/at

Certified value of ²³⁵U/²³⁸U ratio in the spike

R_58Sample

at/at

Certified value of ²³⁵U/²³⁸U in the sample

M_spike

g

Mass of spike (assigned proportions as described in Tables 1 and 2)

M_sample

g

Mass of sample (assigned proportions as described in Tables 1 and 2)

C_238spike

mol/g

²³⁸U in spike calculated from uranium content in U-metal and atom fraction of ²³⁸U in the spike, the latter value is from the certificate

AF_238USample

mol/g

Atom fraction of ²³⁸U in the unknown sample and calculated from the assigned masses and certificate values

δ_{CF58comparator}

Delta value for the correction factor of the comparator ²³⁵U/²³⁸U

(RSE% 7.810995 × 10⁻⁵, Hasozbek et al. 2013)

C_spike

mol/g

Concentration of spike molU/g (taken from the certificate value and diluted estimations are given in Table 3)

AF_238spike

mol/g

Atom fraction of ²³⁸U in spike from the certified value

C_spikeg

mol/g

Spike aliquant concentration (taken from the certificate value and diluted estimations are given in Table 3)

At_wtspike

Atomic weight of spike (CRM 112A)

Wt_Solution

g

Weight of the metal and powder solution (for the dilution and equilibration purposes, 20 ml of vials are taken into account and the mixtures do not exceed over 10 ml.)

Purity

gU/g

Uranium content from the certificate

R_48Sample

at/at

Certified value of ²³⁴U/²³⁸U in sample

R_68Sample

at/at

Certified value of ²³⁶U/²³⁸U in sample

δ _{R58comparator}

Delta factor representing the relative uncertainty on the comparator used for the mass fractionation correction (expanded uncertainty is 0.00065 (k = 2), Hasozbek et al. 2013)