Molecular emission cavity analysis (MECA)1.2is a flame photometric technique which relies on a cool flame source to generate relatively broadbanded molecular emissions, such as S2and BO2and, therefore, directly opposes the trend towards hotter excitation sources and higher resolution monochromators required by the more conventional analyses based on atomic spectra. In practice, it has been found to be complimentary to atomic spectroscopic analyses, being able to determine elements (e.g., sulfur and nitrogen) having their atomic resonance lines in the vacuum UV region of the spectrum by the formation of molecules which emit in the visible and U.V. The advantages offered by the technique as well as the problems facing it are unique.