A New Method for Determination of Total Nitrogen in Aqueous Samples
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This presentation explores a new method of measuring total nitrogen (TN) using a TOC analyzer. Techniques, benefits and results are discussed. For more information, visit ssi.shimadzu.com. Thanks for viewing.
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A New Method for Determination of Total Nitrogen in Aqueous Samples
- 1. 1 / 27 A New Method for the Determination of Total Nitrogen in Aqueous Samples William Lipps Analytical Measuring Instrument Division Shimadzu Scientific Instruments, Columbia, Md., USA
- 2. 22 / 27 Current EPA Definition for Total Nitrogen Requires Two Methods Measure TKN Measure NO3/NO2-N TN
- 3. 33 / 27 Must Use 40 CFR Part 136 Methods for CWA Reporting • Manual digestion! • Manual distillation! • Nessler, IC, titration, ISE, phenate! TKN Methods! • Manual digestion! • Automated distillation/diffusion! • Direct colorimetry! TKN Methods! • IC, reduction colorimetry! NO3/NO2 –N Methods!
- 4. 44 / 27 The “Classical” Kjeldahl Reactions Distilled and Titrated Ammonia Digestion • H2SO4 + 2(NH2)2CO - (NH4)2SO4 +2 CO2 Distillation • (NH4)2SO4 + NaOH - NaHSO4 + H2O + 2NH3 Capture • H2SO4 + 2NH3 - (NH4)2SO4 + H2O Titration • H2SO4 + NaOH - NaHSO4 + H2O
- 5. 55 / 27 Present Day TKN Methods Can Either Distill (Diffuse) or Measure NH4 + in the Matrix Manual Digestion • H2SO4 + (NH2)2CO - (NH4)2SO4 + 2CO2 • Must use catalyst Distillation (required for some methods) • (NH)4SO4 + NaOH - NaHSO4 +H2O + 2NH3 Detection • Titration, ISE, manual colorimetry, automated colorimetry
- 6. 66 / 27 Kjeldahl Method! Substance + Conc. H2SO4 + CuSO4 + K2SO4 Image: Wikipedia 1 Liter RB Flask Water out Water in Conical Flask
- 7. 77 / 27 Operational Comparison of TKN Methods Manual Digestion Distillation Followed By:! Require Final Digest Volume! Require Final Distillate Volume! Titration! no! no! Ion Selective Electrode! no! yes! Manual Phenate! no! yes! Automated Phenate ! no! yes! Block Digestion! Automated Salicylate! yes! N/A!
- 8. 88 / 27 Techniques for Analysis of Total Nitrogen (EPA Only Approves TKN)! Manual Digestion Distillation Followed By:! MDL (mg/L)! Titration! 1.0 ! Manual Phenate! 0.05 ?! Ion Selective Electrode! 0.03! Automated Phenate! 0.01! Block Digestion! Automated Salicylate! 0.1! Auto-GD/pH colorimetry! 0.2! Auto-GD/Salicylate! 0.02!
- 9. 99 / 27 Some Problems With TKN Method for TN Time consuming – 0.5 – 2 hour digestion • Separate distillation and/or analysis Uses hazardous reagents • Boiling sulfuric acid • Metal catalyst Must run NO3 + NO2 separately Not applicable to all N compounds
- 10. 1100 / 27 TKN Recovery in Various N Compounds
- 11. 1111 / 27 New Method is Needed That Measures Total Nitrogen As Single Result Organic Nitrogen! NH3-N! NOx-N! TN! This method can be a lab or online method
- 12. 1122 / 27 Any New Method for TN Should… Obtain equivalent results to TKN and other TN methods Be “rugged” Use few reagents Have a large dynamic range Sample/”handle” a complex matrix
- 13. 1133 / 27 Total Nitrogen Can Be Easily Measured on TOC Analyzer Catalytic Combustion (CC) • 2(NH2)2CO +5O2 + catalyst à 4NO + 4H2O + CO2 Ozonation • NO + O3 à NO2 + O2! • NO + O3 à NO2* + O2! Detection NO2* à NO2 + light !
- 14. 14 / 27 TOC + TN Analyzer!
- 15. 15 / 27 Schematic of TOC + TN Analyzer TN Analysis
- 16. 16 / 27 Total Nitrogen Measurement is Rugged and Uses Few Reagents Measure the sample (dilute) Decomposition : 720℃ with Pt catalyst Formation of NO Formation of NO2 * , - NO2, Photon O2 from air Ozone Emission Obtain the TN Result (every 5 minutes) Electricity
- 17. 17 / 27 Comparison of TN to TKN! TN TKN Measurement contains - Ammonia - Nitrate - Nitrite - Organic nitrogen compounds - Ammonia - Organic nitrogen compounds Consumables Catalyst hydrochloric acid Mercury or selenium, sulphuric acid Analysis time 3-7 min (together with TOC measurement) Minimum 60 min Online realization Easy Not possible
- 18. 18 / 27 TKN and Catalytic Oxidation Recovery in Various N Compounds!
- 19. 19 / 27 Comparison of TN to TKN (QC Samples)!
- 20. 20 / 27 HTCO Methods Obtain Near Equal Results with Persulfate TN on Unknown Samples
- 21. 21 / 27 Recovery (%) of Various Nitrogen Compounds
- 22. 22 / 27 Recovery of TN with Concentration ! 150 microliter sample!
- 23. 23 / 27 Recovery of TN with Concentration! 300 microliter sample !
- 24. 24 / 27 Total Nitrogen 300 Microliter Sample!
- 25. WK46665 Standard Test Method for Total Nitrogen in Water by High-Temperature Catalytic Combustion and Chemiluminescence Detection This test method is under the jurisdiction of ASTM Committee D19 on Water and is the direct responsibility of Subcommittee D19.06 on Methods for Analysis for Organic Substances in Water. Current edition approved [date to come]. Published [date to come]. DOI:10.1520/ Dxxx-xx. 25 / 27 Standard Test Method
- 26. 26 / 27 If Kjeldahl Was Alive Today, He Would Have a Shimadzu
- 27. 27 / 27 Thank you for viewing this presentation. Should you have any questions or require additional information about our research, products or services, please visit our support page: www.ssi.shimadzu.com/support/ @shimadzussi Follow us on Twitter Need More Info?