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6. THE THEORY BEHIND THE CALCULATIONS
6.1 Trace Element Concentrations
Trace element concentrations are calculated using the following equations:
concni = (cpsnij /abundancej) / (yieldni)
1
where:
concni = the concentration of element i in analysis n
cpsnij = the mean count rate (background-subtracted) of isotope j of i in analysis n
abundancej = natural abundance of isotope j
yieldni = cps per ppm of element i in analysis n
The yield of element i in analysis n is determined by:
yieldni = yieldns * Int(yieldni / yieldns)std
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where:
yieldns = cps per ppm of the internal standard s in analysis n
Int(yieldni / yieldns)std = the ratio of the yield of element i in analysis n to the yield of
the internal standard s in analysis n, interpolated over the standard analyses.
6.2 One Sigma Error
The one sigma error estimates use √N counting statistics on the signal and
background counts, propagated through the equations. An assumed 1% uncertainty
(relative) on the elemental concentrations of the reference material, and a 3%
uncertainty (relative) on the values of the internal standard is propagated throughout
the calculations. These values can be changed, or turned off completely by the user
via the “Options” window.
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