Application Note: Simultaneous Determination Of Total Bound Nitrogen (TNb) And Total Organic Carbon (TOC) In Aqueous Samples

Total bound nitrogen (TN_b) consists of dissolved ammonia, nitrates, nitrites, amines, and other organic nitrogen-containing compounds. TN_b measurements represent an alternative to Total Kjeldahl Nitrogen (TKN) analysis for rapid screening of industrial wastewater, drinking water,agricultural run-off, and surface waters.

TN_b analysis can be performed simultaneously with total organic carbon (TOC) analysis by using detectors selective for nitrogen and carbon in tandem. High temperature (720 °C) catalytic combustion oxidizes compounds containing carbon into CO₂ and nitrogen compounds into nitric oxide (NO). Oxygen carrier gas transports to CO₂ and NO reaction gases first into a non-dispersive infrared (NDIR) detector to measure TOC and then into an electrochemical detector to measure TN_b.

This application note describes the use of tandem detectors for simultaneous TN_b and TOC measurements, and oxidation efficiency and conversion of nitrogen compounds into NO using standards and industrial water samples. Instrument operating conditions, calibration data, analytical results, and repeatability are reported.