Modifications for $^{26}$Al

This procedure is essentially the same for $^{26}$Al. The only major difference in the chemical processing is that the quartz sample typically contains a relatively large amount of total Al, so it is not necessary to add Al carrier. Thus, the total number of atoms of stable $^{27}$Al in the sample, here denoted $n_{27,S}$, replaces the number of atoms of the stable nuclide added as carrier. This quantity is:

$$n_{27,S} = \frac{M_{Al,S}N_{A}}{A_{Al}}$$ (15)

where $A_{Al}$ is the molar weight of Al (26.982 g $\cdot$ mol$^{-1}$) and $M_{Al,S}$ is the mass of Al in the sample (g). The mass of Al in the sample is usually determined by ICP-OES or AA analysis of an aliquot taken immediately after the sample has been dissolved. The $^{26}$Al concentration in quartz, $N_{26}$, is then:

$$N_{26} = \frac{1}{M_{q}} \left( \frac{R_{26/27}M_{Al,S}N_{A}}{A_{Al}} - n_{26.B} \right)$$ (16)

where $R_{26/27}$ is the measured $^{26}$Al/$^{27}$Al ratio. The uncertainty $\sigma N_{26}$ is:

$$\sigma N_{26} = \sqrt{ \left( \frac{\partial N_{26}}{\partial R_{... ...\left( \frac{\partial N_{26}}{\partial M_{Al,S}} \sigma M_{Al,S} \right) ^{2} }$$ (17)

where:

$$\frac{\partial N_{26}}{\partial R_{26/27}} = \frac{M_{Al,S}N_{A}}{M_{q}A_{Al}}$$ (18)

$$\frac{\partial N_{26}}{\partial n_{26,B}} = \frac{{-1}}{M_{q}}$$ (19)

$$\frac{\partial N_{26}}{\partial M_{Al,S}} = \frac{R_{26/27}N_{A}}{M_{q}A_{Al}}$$ (20)

One determines the process blank for $^{26}$Al measurements in the same way as for $^{10}$Be, as described above. $^{26}$Al is a much less common nuclide in the environment, so generally $^{26}$Al blanks are less important than $^{10}$Be blanks.