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Ion-chromatographic determination of small concentrations of nitrate in solutions of high salinity

Ion-chromatographic determination of small concentrations of nitrate in solutions of high salinity. Michael Raessler and Ines Hilke Max-Planck-Institut fuer Biogeochemie, Hans-Knoell-Strasse 10, D-07745 Jena, Germany. Common methods for the determination of small amounts of nitrate.

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Ion-chromatographic determination of small concentrations of nitrate in solutions of high salinity

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  1. Ion-chromatographic determination of small concentrations of nitrate in solutions of high salinity Michael Raessler and Ines Hilke Max-Planck-Institut fuer Biogeochemie, Hans-Knoell-Strasse 10, D-07745 Jena, Germany

  2. Common methods for the determination of small amounts of nitrate Capillary electrophoresis Chemilumnescence Electrochemical detection Fluorescence Disadvantage: not appropriate to solutions of high sanility

  3. Ion Chromatography with UV Detection Instrumental Set-up Instrument: Dionex 500 Pump module: Dionex GP 40 Detection: Dionex AD 20 (UV/VIS detector) Sample loop: 100 µl Column: Hamilton PRP X-100, 250 x 4,1 mm Eluent: 0,1 M KCl based on KCl 99,999% „suprapur“ (Merck) Flowrate: 2 mL/min Wavelength: λ = 210 nm

  4. Application:Determination of NO3- in soil extracts of 1 M KCl Problem:KCl of „p.A.“ grade may contain up to 0,005 % Br-  Solution of 1 M CKl contains up to 1725 µg/L Br-  Br- interferes with NO3- determination at trace level

  5. 1500 µg/L NO3- in 1 M KCl of „p.A.“ grade

  6. 150 µg/L NO3- in 1 M KCl of „p.A.“ grade

  7. Reliable determination of NO3-,if concentration ≥ 450µg/L Solution: Spiking 50µL of spike containing 50mg/L NO3- are added to 5 mL of extract Correction factor necessary:  Volume of extract is changed by 1%!

  8. Concentration after additionofspike [µg/L]: 631,1 Mean (N=10) [µg/L]: 629,4±7,8 Recovery [%] : 99,7% RSD [%]: 1,24

  9. Chromatogram of soil extract „B-1“ (523 µg/L NO3-)

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