Extraction and quantitative analysis of water, sediment, soil and biosolids for trace-level trimethylsilanol

摘要

Methylsilanols such as trimethylsilanol (TMS) are considered as the major hydrolytic degradation products of methylsiloxanes, a class of anthropogenic organometallic substances with a wide range of applications. The distribution of these silanols in various environmental compartments, therefore, could provide direct information on silanols' chemical fate and environmental exposure. Existing methods for the quantification of the silanols are not sensitive and robust enough for analyzing environmental media where trace- and ultra-trace-level concentrations may be expected. In the present study, solid-phase extraction (SPE) and solvent extraction in combination with gas chromatography-mass spectrometry (GC/MS) were tested for analyzing water, sediment, soil and biosolids samples for TMS. ISOLUTE (R) ENV+ solid-phase sorbent was found to be most suitable for extraction of water samples for ultra-trace TMS, while direct solvent extraction worked for solids samples such as soil, sediment and biosolids. Coupling with an isotopic internal standard and SPE extraction, direct GC/MS analysis without derivatization can reach a method detection limit for TMS as low as 0.10 mu g L-1 in water. The detection limits for solid samples varied from 0.21 ng g(-1) ww (wet weights) to 10 ng g(-1) ww, mostly limited by background concentrations of TMS in extraction solvents. It was also observed that prolonged sample storage may lead to a reduction in TMS concentrations, regardless of the concentrations of coexisting methylsiloxanes.