Radiocarbon dating process
Historical artefacts like moa bones can be dated using a technique that measures the activity of the radioisotope carbon-14 still present in the sample.
By comparing this with a modern standard, an estimate of the calendar age of the artefact can be made.
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The Wairau Bar in Blenheim is one of the oldest archaeological sites in New Zealand.
Amongst the artefacts that have been found are ancient moa bones.
Some of these have been sent to the Waikato Radiocarbon Dating Laboratory for analysis.
The remaining material goes through a gelatinisation process to free up the bone protein.
Filtration during this phase allows contaminants to be successfully removed. After this process, the resulting material has a spongy texture with an off-white colour. The pre-treated sample is loaded onto a quartz silica boat, which is loaded into a combustion tube.
It is a long tube which is hooked up to a vacuum line.
All air is evacuated from the vacuum line because it has C-14 in it and is a potential contaminant.
Then a stream of oxygen is added into the system and the sample is combusted.
It is during this stage that the carbon present in the sample is converted into carbon dioxide.