Methanol Measurement in Auto Exhaust Using a Gas-Filter Correlation Spectrometer

Spectroscopic methods offer an alternative to wet chemical methods for analysis of methanol emissions from automobiles. The gas filter correlation infrared optical analysis approach appears very promising. This report describes the gas correlation optical system constructed to analyze methanol. The operating characteristics of the system and test data of measurements made on exhaust from a methanol-fueled vehicle are presented. The methanol system has a detection limit of about 0.5 ppm and the system produces a highly predictable output with a calibration curve having a data fit with a multiple correlation coefficient of 0.999. The system also displays excellent rejection to interferences normally present in automobile exhaust.