1.1 This test method covers the determination of total nitrogen (TN) and total dissolved nitrogen (TDN) in surface water, seawater, groundwater, wastewater, and wastewater effluents in the range from 0.2–10 mg/L N. Concentrations from 10–500 mg/L are possible when used in conjunction with manual or automatic dilution, or automatic injection of less sample volume. The EPA 40 CFR Part 136 Appendix B Method Detection Limit (MDL) is 0.05 mg/L N. Higher concentrations may be determined by sample dilution. Lower concentrations may be possible by injecting larger sample volumes. Follow the manufacturer’s instructions. 1.2 The sample is injected onto a platinum catalyst heated at =720ºC. The sample converts into a gaseous phase and is forced through a layer of catalyst ensuring conversion of all nitrogen containing compounds to nitrogen oxide (NO). Reaction with ozone converts the NO to an exited NO2. As the excited NO2 returns to the ground state, it emits radiation that is measured photo-electrically. 1.3 Total and dissolved organic carbon analysis by Test Method D7573 can be analyzed at the same time on the same sample simultaneously using a properly equipped analyzer. (See Appendix X1 for an example of simultaneous TOC data.) 1.4 This test method quantitatively recovers nitrogen from a large range of organic and inorganic nitrogen c