Leibniz laboratory for radiometric dating
C dating of samples containing as little as a few milligrams of carbon, which is ca.
1000 times less than in the conventional techniques.
The purpose of the preparation of samples before radiocarbon measurement is the extraction of material that contains indigenous carbon in a quantity sufficient to measure the The procedure of treatment depends on the sample material.
Usually the samples need physical cleaning or separation under microscope.
The graphite is deposited on the iron powder introduced into a small quartz tube.
The reactor and iron powder are previously heated overnight at 90°C under continuous pumping.
Identifiable samples (macrofossils) with high carbon contents are preferred over sediments and soils.
For high precision we recommend at least 1 mg of carbon after chemical preparation (see: Pre-treatment procedures).
The low natural abundance of ) and, after selection of mass 12, 13, 14 and acceleration to 2.5 Me V, molecular ions are destroyed in a gas stripper (Ar) set to strip the negative of a few electrons to an electric charge of 3.
Prepared graphite targets are sent to an AMS laboratory for the measurement (at present to Pozna Radiocarbon Laboratory, Poland or to Leibniz Laboratory for Radiometric Dating and Isotope Research in Kiel, Germany).
Each batch of samples is accompanied by at least two modern standard (Oxalic Acid) and two background (coal or marble containing no radioactive carbon) samples, prepared in the same way as samples of unknown age which are used for the age calculation.
Approximate sample sizes required for the AMS Please contact us before sending these samples.
* Sample size of dry peat; more material is required if the mineral content is high or the peat is decomposed. The precision of radiocarbon dates for recent samples (younger than 2000 years) of “normal” sample size (1-2 mg of carbon) is better than 0.5% (typically 0.3 - 0.4%) which equals /-40 years (25 - 30 years) for the 1-σ statistical uncertainty of the measured age.