A simple cleanup method for the isolation of nitrate from natural water samples for O isotope analysis.
The analysis of O-isotopic composition of nitrate has many potential applications in studies of environmental processes. O-isotope nitrate analysis requires samples free of other oxygen-containing compounds. More than 100% of non-NO3- oxygen relative to NO3- oxygen can still be found in forest soil water samples after cleanup if improper cleanup strategies, e.g., adsorption onto activated carbon, are used. Such non-NO3- oxygen compounds will bias O-isotopic data. Therefore, an efficient cleanup method was developed to isolate nitrate from natural water samples. In a multistep cleanup procedure using adsorption onto water-insoluble poly(vinylpyrrolidone), removal of almost all other oxygen-containing compounds, such as fulvic acids, and isolation of nitrate was achieved. The method supplied samples free of non-NO3- oxygen which can be directly combusted to CO2 for subsequent O-isotope analysis.
Haberhauer
G
G
Department of Environmental Research, Austrian Research Centers, Seibersdorf, Austria. Georg.Haberhauer@arcs.ac.at
Blochberger
K
K
D000327:Adsorption; D009566:Nitrates / Q000302:isolation & purification*; D010103:Oxygen Isotopes; D014867:Water / Q000737:chemistry*
D009566:Nitrates; D010103:Oxygen Isotopes; D014867:Water