Polydimethylsiloxanes associated with indoor and outdoor airborne particles

Electrical contacts are subject to damage by interaction with silicone oils. These oils, which can cause catastrophic failure of electrical contacts, can arise as vapors or aerosols from components of the environment in which the contacts operate. To assess the potential environmental burden of silicones which could be transferred from source to sink (electrical contact), an aerosol sampling methodology was developed which collects silicone-bearing aerosols. These aerosols, collected with impactors and Teflon filters, are then analyzed by a pyrolysis/mass spectrometric method. As little as 0.1 ng of a given viscosity silicone fluid may be detected using this analytical approach. The fingerprint pyrolysis fragments in this study are cyclic dimethylsiloxanes such as hexamethylcyclotrisiloxane (molecular weight = 222), the detection of which is characteristic of polymeric silicone-bearing contaminants in the atmosphere surrounding the silicone-vulnerable electrical contacts.