Tliis paper compares canister and impinger methods for the analysis of siloxanes in air by gas chromatography/inass spectrometry (GC/MS). Siloxanes are frequently found in commercial and consume? products such as detergents and cosmetics. Most low molecular weight siloxane compounds volatize quickly into the atmosphere; however, some end up in wastewater or landfills when consumer rinse or discard products. Siloxanes have recently emerged as one of the most difficult contaminants to control in sewage and landfill biogases. The biogas can be used to fixel internal combustion engines or turbines that drive electrical generators. Trace impurities in the biogas can form a residue upon combustion and can contribute to reduced engine lifetime. The presence of silicon in the residue combined with the volatility of some siloxanes prompted increased emphasis on improved sample collection and analytical detection of siloxanes.
The first method in die comparison is based on drawing gas phase samples through a series of midget impingers and analyzing for dissolved siloxanes using GC/MS instrumentation. The second method is based on collecting a whole air sample in an evacuated canister and analyzing for siloxanes using GC/MS instrumentation. Tliis paper compares the performance of each method in terms of sample collection, standard sample preparation, initial continuing calibration, and recovery of selected siloxanes over time.
Comparison of Impinger and Canister Methods for the Determination of Siloxanes in Air