Continuous-flow analysis of dissolved inorganic carbon content in seawater

A rapid, continuous-flow determination of total inorganic carbon (TIC) in seawater samples is presented. The method runs on an autoanalyzer Traacs 800 spectrophotometric system and is calibrated versus certified reference materials readily available. A typical analysis speed of 45 samples/h can be reached with an accuracy of 2-3 microM and a precision of approximately 2.5 microM. The analysis requires only a small amount of sample and is thus ideally suited for pore water samples and samples taken from cultures where sample volume is at a premium. The speed of the analysis makes mapping of oceanic surface water characteristics possible. Potential interference of sulfide in anoxic (e.g., pore water) samples can be masked by the addition of a hydrogen peroxide step. Although the latter is a strong oxidative reagent, no significant effect on TIC concentration due to oxidation of (labile) organic matter could be found.