This is particularly relevant for laboratories which use conventional methods of dating.
Bone dating, for example, requires large amounts of sample because the fractions which are usually extracted comprise a small percentage of the total material and the target fractions decompose rapidly.
A stratigraphical diagram should be drawn to enable the dater to understand completely the site and origin of the material, and to consider the ability of the lab to adequately date the sample in question.
The submitter should also indicate the degree of accuracy and precision required.
This should be reported in the submission forms accompanying samples sent to the laboratory.
Contamination may be artificially or naturally caused.
This alters their isotopic ratios and affects their 'true' age.
Organic samples such as wood, charcoal, soil and bone are especially prone to this and should be examined closely before, and after collection, for evidence of root penetration (Hogg, 19).Libby realized that the residual carbon 14 of some samples would be thus affected and suggested that some materials would be more accurate for dating than others.He predicted that charcoal would be the most effective, shell, the least.The following types of sample have been commonly radiocarbon dated: Since the 1950's, a number of researchers have concentrated on investigating and reducing the effects of this post-depositional contamination.This field of inquiry is known as sample pretreatment and it is concerned with removing post-depositional contaminants by isolating sample fractions containing carbon which is autochthonous and therefore accurately dates the event in question.