ABSTRACT The application of chemical ionization mass spectrometry to the instrumental analysis of oxygenates in automobile exhaust gases is described. Initial monitoring experiments demonstrated the capability of this technique to simultaneously measure the instantaneous concentration of formaldehyde@ acetaldehyde@ acrolein@ propionaldehyde@ crotonaldehyde@ butyraldehyde@ valeraldehyde@ and benzaldehyde@ and the total aldehyde concentrations. Preliminary field evaluation established the accuracy and reliability of the instrument via suitable reference tests . The unique ability of this instrument to simultaneously follow the rapidly changing concentrations of nine oxygenates was also verified. However@ it was concluded that the presence of significant amounts of hydrocarbons in the exhaust as interfered with the measurement of acrolein@ crotonaldehyd@ benzaldehyde@ and tolualdehyde. Further@ research resulted in the utilization of ammonia as a reagent gas to overcome this problem and selectively ionize the unsaturated aldehydes in the presence of the hydrocarbons. An improved calibration procedure and inlet system were developed. These advancements resulted in a reduction of sample losses in the inlet system and an increase in the accuracy of the instrument. The response time of the total system was lowered to less than one second. The incorporation of these improvements into the system along with the use of ammonia as an alternate reagent gas has eliminated most of the major problems of the instrument.
API 4121-1971 history
1971API 4121-1971 IMPROVED INSTRUMENTATION FOR DETERMINATION OF EXHAUST GAS OXYGENATE CONTENT