Abstract. Froth flotation is a commonly used procedure for
separating feldspars and micas from quartz for the preparation of quartz
mineral separates to carry out cosmogenic nuclide analysis. Whilst
extracting carbon from quartz we observed in situ carbon-14 (14C)
concentrations which were anomalously high and in excess of theoretical
geological maximum concentrations. Further etching of sample material
reduced carbon yields and 14C concentrations, yet the latter remained
unrealistically high. When quartz from the original whole rock sample was
isolated in our laboratory, we observed even lower carbon yields and
geologically plausible in situ 14C concentrations. After ruling out
unlikely geological scenarios and systematic measurement issues, we decided
to investigate the quartz isolation procedure as a potential source of
14C contamination. We hypothesised that laurylamine (dodecylamine), an
organic compound used as part of the froth flotation procedure, elevates
14C concentrations if residual laurylamine is present. We demonstrate
that laurylamine has a 14C modern carbon source and thus has the
potential to influence in situ 14C measurements if present in minute
but measurable quantities. Furthermore, we show that insufficient sample
etching results in contaminant 14C persisting through the step heating of
quartz that is subsequently collected with the in situ component released at
1100 ∘C. We demonstrate that froth flotation contaminates in situ
14C measurements. We provide guidelines for the preparation of quartz
based on methods developed in our laboratory and demonstrate that all froth-flotation-derived carbon and 14C is removed when applied. We recommend
that the procedures presented be used at a minimum when using froth
flotation to isolate quartz for in situ 14C measurements.
In-Situ Synthesis and Characterization of Nanocomposites in the Si-Ti-N and Si-Ti-C Systems