Application of microsublimation for sample purification in compound-specific radiocarbon analysis

This article presents the development and application of a microsublimation apparatus aimed at improving the purity of ultra-small samples for compound-specific radiocarbon analysis. Accurate radiocarbon (¹⁴C) measurements require the effective isolation of biomarkers, yet procedural steps, such as chromatography and sample transfer, introduce contamination risks that can skew results. Here, we present a novel approach to remove contamination resulting from chromatographic isolation. The apparatus, constructed primarily from aluminum, allows solvent-free sublimation of multiple samples under vacuum. A constant contamination assessment showed a blank mass of 1.35 µg of carbon with a F¹⁴C of 0.33, indicating minimal contamination with ¹⁴C-depleted carbon. The apparatus demonstrated high efficacy for compounds with higher melting points, such as amino acids and dyes, while compounds like alkanes showed lower recovery rates. These findings confirm the potential of microsublimation to enhance post-chromatography sample purity and improve the accuracy of ¹⁴C measurements, though challenges remain for certain compound classes.