The development and improvement of benzene synthesis for radiocarbon dating by liquid scintillation counting was started at LATYR in 1981. The basic technique employed was described by Polach, Gower & Frazer (1972). The line of benzene synthesis is similar to that used by Coleman et al (1972). The pretreatment of the samples and transformation to CO2 has been previously described (Figini et al, 1984). The conditions of measurement were partially determined according to Pearson (1979). Results of measurements of interlaboratory check samples using the technique described are given.

The Radiocarbon Dating Laboratory was established at the Middle East Technical University in the Physics Department with the equipment provided by the British Government through former CENTO auspices and financial support by the Ford Foundation. This list reports on 14C dates measured up to July 1987.

GEOTOP is the geochemistry and geochronology research center of the Université du Quebec à Montréal (UQAM). The Radiocarbon Laboratory was established to meet the growing demand for radiocarbon dating in Québec. The laboratory was founded by Claude Hillaire-Marcel. The first measurements were completed in October 1978. The laboratory was managed by Pierre Pagé until May 1985. Serge Occhietti and Pierre Pichet are presently in charge. Technical maintenance is under the direction of Claude Jacob.

Procedures and equipment used in the University of Wisconsin laboratory have been described in previous date lists. Except as otherwise indicated, wood, charcoal, and peat samples are pretreated with dilute NaOH—NA4P2O7 and dilute H3PO4 before conversion to the counting gas methane; when noted, marls and lake cores are treated with acid only. Very calcareous materials are treated with HCL instead of H3PO4. Pretreatment of bone varies with the condition of the bone sample; solid bone with little deterioration is first cleaned manually and ultrasonically. The bone is treated with 8% HCL for 15 minutes, then dilute NaOH—Na4P2O7 for 3 hours at room temperature, washed until neutral, and the collagen extracted according to Longin (1971). Charred bone is treated with dilute HCL, NaOH—Na4P2O7, and then dilute HCL again.

A microwave oven is used to pretreat carbonate samples prior to graphitization and radiocarbon dating by accelerator mass spectrometry. The method reduces the risk of contamination of small carbonate samples and provides a fast and convenient method for the acid evolution of CO2.

A standard sample (SS) of 14C-specific β activity has been created based on benzene containing radioactive carbon diluted with “dead” benzene.