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. The carbon dioxide is collected and bubbled through various chemicals in the line, which purify it, and the amount of carbon dioxide that has been collected is measured.