A low-blank photochemical extraction system for concentration and isotopic analyses of marine dissolved organic carbon

Steven R. Beaupré, Ellen R. M. Druffel, Sheila Griffin
Limnol. Oceanogr. Methods (2007) 5:174-184

We report the development of a modified, low blank, UV oxidation and vacuum line system to convert marine dissolved organic carbon (DOC) into carbon dioxide for concentration, D¹⁴C, and d¹³C analyses. The system performs quantitatively and precisely with preservation of isotopic signatures (± 3‰) based on additions of pure IAEA standards. Analytical blank reduction from <1.5 µM to 0.2 µM enabled a decreased detection limit from a sample size of ~650 ml to 30 ml using a simple dilution technique. Combined with advances in analyses of ultra-small (2 µg C) samples using accelerator mass spectrometry (AMS), the technique provides a means for measuring D¹⁴C values in samples that were previously not possible.