||ANALYTICAL PROGRAMMES||Left - 5 MV accelerator mass spectrometer (NEC), SUERC|
We prepare c. 1,300 samples and quality control standards to graphite every year, which are analysed at the SUERC AMS Facility, located adjacent to the NRCF (East Kilbride), and which currently has two accelerator mass spectrometers: 5 MV and 250 kV single stage. Submitted samples are pre-treated, chemically and/or physically to remove any unwanted material from each sample before converting them to carbon dioxide (by combustion or, for carbonates, by acid hydrolysis) and then to graphite. The Radiocarbon WEB-info site has a comprehensive section on pre-treatment methods and the reasons for using the different methods. A typical sample for AMS dating would contain 1-2 mg of carbon (the weight of raw sample material depends on the sample type (see below), although we do prepare smaller samples). Larger samples are welcome and in some cases, for homogeneity reasons, may be more appropriate. All radiocarbon measurements are performed at the SUERC AMS facility using either the 5 MV or 250 kV NEC accelerator mass spectrometers.
The following outlines the types of samples we prepare at NRCF (East Kilbride). Please contact us if you have other requirements not listed below. For routine AMS 14C analysis, only 1-2 mg carbon is required, although we can work with smaller or larger amounts. Although all samples are now analysed by AMS, we still retain the capability to analyse the large (1-2 g carbon) sized samples that would previously have been analysed using the radiometric (liquid scintillation counting) method - this may be appropriate for samples with multiple sources of carbon such as soils.
In estimating how much carbon your raw sample contains, the % carbon content should be taken into account, as well as the sample purity (is there non-carbon material adhering to the sample, e.g. clay minerals or sand, which will affect the overall % carbon content by dry weight?) and whether your sample is wet. If you are unsure about how much material to submit please contact us.
Sample collection and storage
Guidance on the collection and storage of samples for radiocarbon analysis/dating can be obtained from the Radiocarbon WEB-info site. In general, the main objective should be to avoid the addition of extraneous material. If you are unsure about sample collection or storage please contact us.
Since 2005 the lab ceased to perform radiocarbon measurement by the liquid scintillation counting technique which determined 14C activity via the measurement of beta decay. This method required samples of greater than c. 1 g of carbon and since the changing needs of the user community have been for the analysis of progressively smaller samples, the lab now concentrates on analysis using AMS only. It is important to note that the lab still retains the ability to analyse all large samples that would previously have been measured using the radiometric method.