A rapid, precise and sensitive method for the determination of total nitrogen in natural waters

A rapid, automated method is described for the accurate determination of total combined nitrogen (TN) in natural waters. This methodology allows for TN analyses to be performed at three times the rate of previous techniques. The method is shown to be sensitive for a wide range of TN concentrations that may be found in various aquatic environments. The detection limits of this methodology are 2.0 μM (freshwater) and 2.3 μM (seawater). TN and TIN analysis of surface water samples from 300 sites inshore and offshore of south Florida, USA revealed predictable gradients in nitrogen concentrations. TN ranged from 7.56 μM offshore to 108.87 μM inshore. Organic forms of nitrogen constituted approximately 90% of the total nitrogen pool.