STATIC MASS-SPECTROMETRY FOR THE DETERMINATION OF ACTIVE GASES

A static mass spectrometric method has been developed for the determination of the active gases CH4, CD4, CO, CO2, and N2 in amounts <10-10 g. The problems of background and sample degradation by the hot filament have been considered. The deuterocarbon gas CD4 is by far the most suitable species for study by the technique. An ultimate detection limit of 10-14 g C as CD4 would appear feasible. The precision of measurement for 10-9 g amounts of C as CD4 is better than ±0.1 %. Methane (CH4) is also very stable under the source conditions used. Background and instability problems exist for CO and N2; possible solutions are discussed. Static mass spectrometry will not be of use for CO2 without chemical pretreatment of the gas. A number of applications for the method have been outlined; one possibility is that further developments may allow high sensitivity stable carbon isotope analysis. © 1979, American Chemical Society. All rights reserved.