If at all possible, please send only the amount required for the radiocarbon dating. Minimum and optimum weights are given in the table below. For soils and sediments the carbon content varies greatly. If the % carbon is unknown then please contact us about conducting testing a sample first.
|Material Type||Minimum Weight||Optimum We ight|
|Wood||5 mg||20 mg|
|Charcoal/Charred seeds||10 mg||30 mg|
|Bone/Antler/Teeth||500 mg||1000 mg|
|Cremated Bone||1.5 g||3 g|
|Shell/Carbonate||6 mg||20 mg|
|Peat (Humic acid fraction to be dated)||30 mg||100 mg|
|Peat (whole peat to be dated)||20 mg||50 mg|
Bone, antler, and teeth
Our ability to radiocarbon date bone and other collagen containing samples such as antler, horn, and teeth (dentine) depends upon the preservation of the protein component of the bones (mostly collagen). The preservation depends largely on the burial conditions (soil acidity, temperature, moisture etc.).
We pre-screen bones for nitrogen content which allows us to predict whether a bone has sufficient collagen preservation about 85% of the time based on research by Oxford Radiocarbon Accelerator Unit. Bones with low nitrogen content will not be processed to collagen. There is no charge for the pre-screening, however please see our for dating at guidelines for selecting bones
We remove the mineral component of the bones because it is not reliable for dating. We then purify the remaining material to concentrate the collagen and remove as much soil contamination as possible following the procedure given in Brown et al. 1988 and using the ultrafilter cleaning method of Bronk Ramsey et al. 2004. A collagen yield of less than ~1% means that the sample was not well preserved and is unacceptable for dating purposes. These samples will not proceed to the final AMS stages. For samples with sufficient sample material remaining after AMS analysis, stable isotopes (13C and 15N) and C to N ratios will be measured on our EA-IRMS as a further test of collagen quality.
Always send clean, dry bones for dating.
Wood & Charcoal:
As trees can be long-lived, wood and charcoal may have an in-built age associated with them If possible, either small twigs or outer rings of the tree should be selected for dating. If these are not available then short-lived species should be selected if possible; identifications must be done before samples are sent for radiocarbon dating.
Because soil is not a 'closed' system, it is not a good choice for radiocarbon dating, unless it is for the purpose of carbon storage and turnaround studies. In other words due to bacterial action and water movement, different carbon compounds may be leached from the soil leaving behind more resistant, older carbon while more recent carbon may be absorbed.
Lakes in 'hardwater' regions may have a radiocarbon age offset from the contemporaneous terrestrial environment. This 'freshwater reservoir effect (FRE)' can be hundreds of years. The FRE may be estimated by radiocarbon dating the surface sediment, aquatic plants or mollusks but it may also have varied over time. This is less of a problem in 'softwater' regions, but glacial meltwater may have added old carbon to some lakes. Identifiable terrestrial plant remains (macrofossils) are therefore usually the preferred samples for radiocarbon dating lake sediments. There is the possibility of re-worked macrofossils being deposited in the lake. If at all possible, fragile macrofossils that would not have survived transport are preferred. If terrestrial macrofossils are not available then humic acids may be the best alternative provided the lake has a reasonably high organic carbon content and the sediments have not been dried out and exposed at times (in that case see Soil above).
Identifiable macrofossils are the preferred choice for radiocarbon dating in peat bogs. They should be selected and rinsed in deionised, distilled or ultra-pure water and stored in water with a few drops of 10% HCl or dried at low temperature (<60oC). If macrofossils are not available, bulk peat samples can be analysed. Please remove any roots from bulk samples before sending them. Bulk peat samples should be dried or stored in a cool, dark place. Do not wrap them in aluminum foil because the acidic nature of the peat will cause it to disintegrate.
Marine samples have approximately a 400 year offset from contemporaneous terrestrial samples due to the Marine Reservoir Effect (MRE). This can be corrected for in calibration using radiocarbon ages of modern (pre-nuclear testing) shells which have been measured for many regions of the ocean. The MRE may also vary over time which adds some uncertainty to the calibrated age range. The most reliable molluscs to radiocarbon date are bivalves since many of these feed directly on plankton in the ocean although burrowing species should be avoided. Some species of molluscs may ingest limestone which can cause an age offset but may be fine in non-calcareous regions. The shells of foraminifera are also often radiocarbon dated to provide ages for marine sediment cores. Generally monospecific planktonic samples are selected for this purpose.
Please indicate on the submission form if there are any known contaminants which could effect the radiocarbon age. These include preservatives used in conversation such as wax, varnish, glue, or insecticides and hydrocarbons. In many cases we may be able to remove the contaminants if we know about them. We cannot be responsible for incorrect results if you don't inform us about contaminants. Substances ordinarily found in nature such as soil and humic acids will be removed in pretreatment and don't need to be specified.
If there is any possibility that the samples were collected, processed, or stored where radioactive 14C or stable carbon 13C tracers were used at any time, it is imperative that we be informed before samples are sent. We can arrange a test of the storage or laboratory area if the use of tracers is a possibility. We reserve the right to refuse to process samples of questionable provenance (shipboard sample collection, biomedical facilities etc.)
Packaging & shipping
Samples should be cleaned and dried (except for peats and sediments which may be sent wet if kept cool and dark). Samples may be sent in plastic sealable bags or glass or plastic vials. Glass vials should be used for samples such as forams or small macrofossils which may build up static electricity and be difficult to remove from plastic vials. Larger samples may be wrapped in aluminum foil if desired, with the exception of peats and soils which may be acidic and react with the foil.
Irreplacable samples should be sent by registered mail or delivery service.
Samples should be shipped to:
c/o Paula Reimer or Stephen Hoper
Archaeology & Palaeoecology Building
42 Fitzwilliam Street
Belfast BT9 6AX
Brown, T. A., Nelson, D. E., Vogel, J. S., and Southon, J. R. (1988). Improved Collagen Extraction by Modified Longin Method. Radiocarbon 30, 171-177.
Bronk Ramsey, C., Higham, T., Bowles, A., and Hedges, R. (2004). Improvements to the pretreatment of bone at Oxford. Radiocarbon 46, 155-163.