Equivalence ratios have been determined with two different techniques. The first, called the phi-meter, is a modification of the phi-meter earlier presented by Babrauskas et al. , while the other utilizes a mass spectrometer as the analyzing instrument. Results are presented from experiments with both techniques and a discussion concerning the deviations from theoretically calculated results is presented. The two methods presented are possible candidates in situations where global and/or local equivalence ratios need to be measured. In its present conformation, the phi-meter gives more consistent results than the mass spectrometer approach but the latter can be considerably improved by using a mass spectrometer with better resolution.