An improved wet oxidation method for radiocarbon analysis of dissolved organic carbon in a simulated freshwater matrix

Abstract The analysis of the radiocarbon age of dissolved organic carbon (DOC) is fundamental for understanding the aquatic component of the global carbon cycle, yet the technique is not routinely available at radiocarbon laboratories. This study presents validation experiments for an improved wet oxidation method for 14 C-DOC analysis in a freshwater matrix. Emphasis in design protocol for the method was placed on the quantitative removal of inorganic carbon, and a background level consistent with modern accelerator mass spectrometry (AMS) radiocarbon measurements. The method utilizes a pre-oxidized potassium persulfate oxidant in crimp-sealed vials with rigorous multi-stage helium purging to achieve and maintain a sample without atmosphere carbon dioxide and the contamination of modern 14 C ( 14 C-free). Method validation of 14 C-free samples are demonstrated with procedural blanks, phthalic anhydride (PhA), and an International Atomic Energy Agency Oxalic Acid standard (IAEA-C8).