Mass Spectrometric Determination of Nitrogen Oxides in Turbocharged Diesel Engine Exhaust

A mass spectrometer has been used to study the nitrogen oxides emissions from a diesel engine equipped with two different turbochargers. Methods of accounting for interference effects from other gases in the exhaust have been described. Results compare well with those obtained by a chemiluminescent analyzer in the trend of nitric oxide emission as a function of engine speed, with the emission level reaching a maximum at where the maximum torque occurs. Discrepancy is found in the absolute levels of nitric oxide between the results of the two instruments but overall agreement is reasonable.