Performing an Isotope Dilution Analysis

The concentration in an isotope dilution analysis is calculated as follows.

 

c: Concentration (The unit is determined from the weight of the spike and the weight of the sample.)

K: Normal atomic weight / atomic weight of the spike

W: Weight of the spike

Asp, Bsp: Abundance ratios of the isotopes A and B in the spike (Spiked isotopic abundance ratio)

M: Weight of the sample

A, B: Abundance ratios of the isotopes A and B in the sample (Stable isotopic abundance ratio)

d: Dilution factor

 

The "ratio of isotopic abundance ratios" and the "ratio of CPS counts" described above are the ones for the standard solution. Because the isotopic abundance ratio is known, the "ratio of isotopic abundance ratios" can be calculated. The "ratio of CPS counts" can be obtained by analyzing each isotope using the instrument, and if the "ratio of CPS counts" is equal to the "ratio of isotopic abundance ratios", the "mass bias correction factor" is 1.