Status Report on Sample Preparation Protocols Developed at the LMC14 Laboratory, Saclay, France: From Sample Collection to ¹⁴C AMS Measurement

Abstract

The main objective of this report is to present the dating process routinely applied to different types of samples at the Laboratoire de Mesure du Carbone 14 (LMC14). All the results and protocols refer to our procedures over the last 5 years. A description of the sorting and chemical pretreatments of the samples as well as the extraction and graphitization of CO2 are reported. Our last study concerning the degradation of the blank level according to the storage time of the targets between graphitization and accelerator mass spectrometry (AMS) measurement is also presented. This article also provides information on how to submit a valid laboratory sample. We give details relating to sampling procedures on site as well as contamination issues relative to the 14C dating methodology.

Absolute dating of lead carbonates in ancient cosmetics by radiocarbon

“…Iron was heated at 600°C while the water was trapped at -78°C. The pressure in the reaction lines was monitored and the reduction ended when the slope of the pressure became below 0.3% in 3 to 4 h. For some samples, due to the presence of Cl (from phosgenite) and/or S (from galena), we had to apply a Sulfix treatment to achieve the carbon formation reaction 16 .…”

“…The wood and reed materials of the cosmetics containers were prepared using the standard acid-base-acid method (0.5 M HCl at 80°C,1 h/ 0.1 M NaOH at 80°C, 1 h/ 0.5 M HCl at 80°C, 1 h) 16 and then dried under vacuum overnight (60°C-0.1 mbar). CO 2 was obtained by combustion (5 h, 850°C) in a sealed tube with an excess of CuO (400-500 mg) and a 1-cm Ag wire.…”

“…We measure the 14 C/ 12 C ratio by accelerator mass spectrometry (AMS) in each cosmetic powder prepared by thermal decomposition and graphitization 16,17 (Methods). We show that atmospheric carbon dioxide was incorporated in some lead carbonates during their synthesis.…”

On the long-lasting sequences of coral reef terraces from SE Sulawesi (Indonesia): Distribution, formation, and global significance

“…This facility is based on a 9SDH-2 Pelletron tandem from National Electrostatic Corporation. The procedure is extensively described in Dumoulin et al (2017).…”

Radiocarbon Dating at Groningen: New and Updated Chemical Pretreatment Procedures

“…The aqueous pretreatment procedures employed by Groningen are very similar to most other academic 14 C laboratories (e. g. Brock et al 2010;Dunbar et al 2016;Dumoulin et al 2017;Steinhof et al 2017). For human, animal and plant-based samples, the core is an acid-base-acid (ABA) procedure designed to eliminate geological carbonates, supramolecular humic substances from the soil, and any atmospheric CO 2 absorbed during the alkaline phase.…”