Linear and cyclic methylsiloxanes in air by concurrent solvent recondensation–large volume injection–gas chromatography–mass spectrometry

In the present work, a simple and fast method for the analysis of linear and cyclic methylsiloxanes in ambient air based on active sampling combined with gas chromatography – mass spectrometry (GC–MS) was developed. The retention efficiency of five sampling sorbents (activated coconut charcoal, Carbopack B, Cromosorb 102, Cromosorb 106 and Isolute ENV+) was evaluated and Isolute ENV+ was found to be the most effective. A volume of 2700 L of air can be sampled without significant losses of the most volatile methylsiloxanes. To improve the sensitivity of the GC–MS method, concurrent solvent recondensation – large volume injection (CSR–LVI), using volumes up to 30 µl of sample extract, is proposed and limits of quantification down to 0.03–0.45 ng m−3, good linearity (r>0.999) and precision (RSD %<9%) were obtained. The developed method was applied to the analysis of ambient air. Concentrations of linear and cyclic methylsiloxanes in indoor air ranging from 3.9 to 319 ng m−3 and between 48 and 292668 ng m−3, were obtained, respectively, while levels from 6 to 22 ng m−3 for linear and between 2.2 and 439 ng m−3 for cyclic methylsiloxanes in outdoor air from Barcelona (Spain), were found.