Shipboard automated determination of trace concentrations of nitrite and nitrate in oligotrophic water by gas-segmented continuous flow analysis with a liquid waveguide capillary flow cell

Incorporation of a liquid waveguide capillary flow cell in a gas-segmented continuous flow auto-analyzer significantly enhances the sensitivity of automated colorimetric analysis. Nanomolar concentrations of nitrite and nitrate in oligotrophic surface seawater can be accurately determined. The advantages of this technique are low detection limit, high precision, and automation for rapid analysis of a large number of samples. This technique was successfully used on shipboard measurements of about 1000 seawater samples during a one-month cruise in the North Atlantic.