Application and field validation of a continuous nonmethane organic carbonanalyzer

Nonmethane organic carbon (NMOC) is a measure of total organic carbon excep t for that from CH4. We recently reported the development of online instrum entation for continuous NMOC monitoring. This instrument, referred to as C- NMOC, uses a microsorbent trap in combination with a gas-sampling valve as the sampling interface. A conventional oxidation/reduction NMOC detector is used for quantitation. In addition to being an online concentrator and an injector, the microtrap serves as a separator that isolates NMOC from H2O, CO, CO2, CH4, and other background gases. Therefore, the C-NMOC is able to handle high concentrations of background gases commonly found in stack emis sions and has detection limits in the ppb levels. This paper reports the results of field validation and testing of a C-NMOC analyzer at a coatings facility in the eastern United States. The instrumen t was able to monitor the process transients in real time, based on which c orrective actions could be taken. It demonstrated good accuracy, high preci sion, and long-term stability.