F.A.Q. _ radiocarbon dating

 

Sample types and their required size

The masses listed above refer to dry weights and partially cleaned samples. Smaller weights can influence the success of the chemical pre-treatment of the sample and/or the precision of the results.

Mortar

Our laboratory is able to date lime mortar samples prepared by calcination and carbonation (non-synthetic mortars) by the AMS method, given that the C content is incorporated into the carbonate by atmospheric CO2 during the carbonation process.

Please write in the “Submission form” (if applicable) some information on the mortar (e.g. the type of aggregates, the mortar type, preliminary analyses performed on the example, e.g. SEM - Scanning electron microscopy - analysis, etc.)

Bone

The success of the bone dating depends on collagen content. The quantity and quality of the collagen (the organic component which is extracted and dated) depend on the bone burial environment and its condition (pH, T, soil acidity…). The bone visual inspection is the first step in order to obtain an indication of the collagen content. For example, dense bones should contain enough collagen for dating, while soft, friable and porous bones usually should not have collagen or sufficient collagen for dating. For the bone date calibration, it is important to specify in the submission form (in the "particular notes on the sample” paragraph) if, in their lifetime, individuals may have had a terrestrial diet rather than marine or freshwater, deducible from the context in which the sample was found or from other isotopic analysis.

It is important that the bone sample is in a good state of preservation. We suggest, if possible, to use femora or, an alternative, teeth.

Paper (parchment, papyrus) and textiles

 At least 1 cm2 of surface is recommendable for the paper (parchment, papyrus) and textiles to achieve a good efficiency of the chemical pre-treatment.

Soil

The soil required weight depends on two factors: 4-6 g if you want to extract the fractions from the soil; 150-250 mg if you want to measure only the bulk soil.

What happens if the sample does not contain enough material for dating?

In the case, after a first visual inspection, the sample does not contain enough material for dating, the customer will be contacted to choose if new material will be sent or to cancel the order for this sample. If, after the chemical pretreatment, the residue of the material is poor, we agree with the customer about the continuation of the analysis.

 

Samples packing instructions

The samples to be sent must be placed in plastic bags or Falcon type tubes or in aluminum paper or in microtubes (Eppendorf type) in case of very small samples. The code corresponding to each sample must coincide with the one written in the submission form.

Customer is asked to assign an identification code (his own choice) to each submitted sample. Please,don’t affix labels with glue or other material directly on the sample. Please, affix the label with the sample code on the package containing the sample.

For each sample, the surplus material will be kept in the laboratory for 12 months; at the end of this time period, it will be discarded.If you want to get back the leftover material, please clearly state it in the order. The shipping costs will be charged to the customer.

What is turnaround time?

Delivery of the final report with the results is guaranteed within 6 working weeks from sample arrival at the lab.

What is typical precision?

Typical precision in the radiocarbon age determination is ± 25 years for recent samples (up to about 2 ka BP).

The radiocarbon dating is applicable to prehistoric or historic artifacts that are made ​​prior to about 1700, with a precision of ± 25 years. After that date, due to the so-called Suess effect, the method is not able to distinguish among different dates within the 1700 – 1955 interval. Finally, thanks to high production of 14C due to the nuclear explosions in the atmosphere in the postwar period, the method is able to date, with higher precision (on the order of one year), a finding more recent than 1955.

 

What is the meaning of δ13C value indicated in the report?

The δ13C values indicated in the report do not refer to the natural isotopic fractionation of the sample, but include those resulting from the treatment (measured on line) as well as the so-called "machine δ13C." These δ13C values are measured solely in order to make the correction for the fractionation of the isotopic ratio 14C/12C that provides the date, but they can be very different from natural fractionation. In other words, the on-line measurement ensures the proper correction for the fractionation of dating, but it is not usable for other considerations.

The natural isotopic fractionation can be measured by IRMS in our laboratory, but it is independent on the measurement we take for dating purposes;we commonly carry out IRMS analysis for δ13C only after explicitcustomer’ s request.

 

If you would like to use our dating system, the procedure to follow is:

- send by e-mail a request for an offer to the following address: valorizzazione@innova.campania.it , specifying the number and kind of samples to be analysed.

- once the offer is received, send us a signed order, specifying the purchaser data and the samples’ number, plus the "information and submission form" to “INNOVA S. C. a R. L.” by email to valorizzazione@innova.campania.it. Please, fill a different “submission form” for each sample.

- send the samples to be measured and the submission forms to the following address: Prof. Filippo Terrasi, Dipartimento di Matematica e Fisica - Seconda Università degli Studi di Napoli, Viale Lincoln 5, 81100 CASERTA, ITALY;

Usually the sampling is performed by the customer, eventually after our instructions. In case our intervention for sampling is required, travel expenses will be charged.

 

More information:

 


www.innova.campania.it