Lac-Uff Status Report: Current Protocols and Recent Developments

Abstract

The Radiocarbon Laboratory of the Fluminense Federal University was installed in 2009, and its NEC Single Stage Accelerator Mass Spectrometry system has been operational since 2012. As the first 14C-AMS facility in Latin America, the LAC-UFF became a reference center for radiocarbon (14C) dating in Brazil. Over the years we have implemented pretreatment protocols for several kinds of materials, such as cellulose, soil, bone, and biofuels. In the present paper we describe our current protocols for the preparation of these types of samples. Moreover, after 10 years of operation, with the aim of expanding the range of materials we are able to analyze, we report the results of several tests to improve accuracy, precision and background levels. For example, here we discuss how isotopic fractionation during the graphitization and measurement steps has been controlled. Concerning results interpretation, our research group has been using OxCal chronological models to analyze different contexts such as stromatolite growth, tree rings, soil deposition and marine reservoir effect (MRE) determination.

ASSESSING THE 14C MARINE RESERVOIR EFFECT IN ARCHAEOLOGICAL CONTEXTS: DATA FROM THE CABEÇUDA SHELL MOUND IN SOUTHERN BRAZIL

“…Carbonate: At the Radiocarbon Laboratory of the Universidade Federal Fluminense (LAC-UFF), carbonate pre-treatment follows the standard protocols for the preparation of inorganic samples (Oliveira et al 2021). The remains of organic tissues were removed manually with scalpels and washing with MilliQ water was not necessary.…”

“…Charcoal: At the LAC-UFF, charcoal samples underwent an ABA treatment (Oliveira et al 2021). This consisted of a wash with HCl 1.0M (2 hr at 90ºC), a wash with NaOH 1.0M (1 hr at 90ºC) and a second wash with HCl 1.0M (2 hr at 90ºC), performed in this order.…”