SUPERCRITICAL-FLUID CHROMATOGRAPHY MASS-SPECTROMETRY AND MATRIX-ASSISTED LASER-DESORPTION IONIZATION MASS-SPECTROMETRY OF CYCLIC SILOXANES IN TECHNICAL SILICONE OILS AND SILICONE RUBBERS

Supercritical fluid chromatography in combination with mass spectromet ry is used for determining cyclic siloxanes beside linear methyl and h ydroxyl ''end-capped'' siloxanes. Electron impact ionisation and chemi cal ionisation techniques are utilized for identifying cyclic siloxane s in technical silicone oils and silicone rubber. Ammonia as reagent g as is preferred in the higher-molecular-mass range. Matrix-assisted la ser-desorption ionisation mass spectrometry can be useful as a supplem entary method for characterizing smaller amounts of both cyclic and li near siloxanes as well as silanols in the higher-molecular-mass range.