Determination of decamethylcyclopentasiloxane in air using commercial solid phase extraction cartridges

Decamethylcyclopentasiloxane (D₅), a high production volume chemical used in personal care products, has been designated for regulation in Canada and is under review in the EU because of concerns about its persistence and potential for bioaccumulation in the environment. D₅ is a volatile compound expected to be found primarily in air, but there is little information on atmospheric concentrations due to the lack of sensitive analytical methods. Here a simple and sensitive method to determine D₅ in ambient air is presented. The challenge in the environmental analysis of D₅ is avoiding contamination. Our method is based on the high trapping efficiency of the sorbent Isolute ENV+, combined with a comparably high sampling rate. A small amount of sorbent (10 mg) is eluted in a small volume of n-hexane (0.1–0.6 mL), which is injected onto a GC/MS system without further processing. The simplicity of the method enables the use of a field blank for every sample to trace contamination. The method provides low limits of quantification (∼0.3 ng/m³), good repeatability and limited breakthrough (∼1%). By lowering the limit of quantification compared to published work by almost two orders of magnitude, it became possible to quantify D₅ in ambient air at locations remote from strong point sources. The concentrations at a rural Swedish site ranged from 0.7 to 8 ng/m³ over a period of 4 months.