Direct mass spectrometric analysis of the 18O/16O ratio in sulfur-containing organophosphorus compounds

High precision measurements of the ¹⁸O/¹⁶O ratio in bis-(5,5-dimethyl-2-oxo-1,3,2-P-dioxaphosphorinanyl)-sulfide and P¹-oxo-P²-thiono(5,5-dimethl-1,3,2-dioxaphosphorinanyl)oxidee have been carrid out using a Finnigan 4000 mass spectrometer.