Fractionation dating method
Any carbon-containing material that affects the carbon 14 content of any given sample is therefore a contaminant.
Important Note on Pretreatment – It is important to understand the pretreatments which are going to be applied to samples since they directly affect the final result.
However, limiting ages or "backgrounds" are also determined by process blanks which correspond to the method used to extract the carbon from the sample.
» NOSAMS General Statement of C from contamination introduced during chemical preparation, collection or handling.
Therefore a 1% error in fraction-modern leads to an 80 year error in the age.
Ages are rounded according to the convention of Stuiver & Polach, shown below.
This correction is performed as follows: $$Fm_ = Fm_ ( Fm_ - Fm_b)\frac$$ Where \(M\) is sample mass, and \(M_b\) and \(Fm_b\) are the mass and Fm of the blank.
Fraction Modern is a measurement of the deviation of the C is also affected by natural isotopic fractionation.
Materials such as charcoal, wood, peat, and textiles typically undergo the acid-alkali-acid (AAA) method before radiocarbon dating.Thus, ages are limited by the age of the process blanks (more on that below) and by the statistical uncertainty of the C ratios of the blank, the sample and the modern reference, respectively.For small samples, blank contribution as a fraction of sample mass becomes a more important term, so a mass balance blank correction is applied.One other situation that limits the age (if not already limited by the background age) is the error of the AMS result.If twice the reported error of the Fraction Modern (let's call this 2sigma) is larger than the sample Fraction Modern, then a limiting age is reported.