Radiocarbon dating benefits
The collagen fraction usually yields more reliable dates than the apatite fraction (see Dates on bones).
In addition to various pre-treatments, the sample must be burned and converted to a form suitable for the counter.
AMS technology has allowed us to date very small samples (such as seeds) that were previously undatable.
Since there are practical limits to the age range of the method, most samples must be younger than 50,000 years and older than 100 years.
The sample must be destroyed in order to measure its c14 content.
The first measurements of radiocarbon were made in screen-walled Geiger counters with the sample prepared for measurement in a solid form.
Pre-treatment seeks to remove from the sample any contaminating carbon that could yield an inaccurate date.
In contrast, methane made from petroleum products had no measurable radioactivity.
For example, it was once standard practice to simply burn whole bones, but the results were eventually seen to be unreliable.
Chemical methods for separating the organic (collagen) from the inorganic (apatite) components of bone created the opportunity to date both components and compare the results.
These so-called "solid-carbon" dates were soon found to yield ages somewhat younger than expected, and there were many other technical problems associated with sample preparation and the operation of the counters.
Gas proportional counters soon replaced the solid-carbon method in all laboratories, with the samples being converted to gases such as carbon dioxide, carbon disulfide, methane, or acetylene.