Cavitands as superior sorbents for benzene detection at trace levelElectronic supplementary information (ESI) available: synthetic procedures for the preparation of cavitands 2, 3; 29Si and 13C CP/MAS NMR spectra of MeCav and QxCav coated silica; desorption pattern of BTX observed for Tenax TA® at 50 °C; GC traces obtained from the desorption at 75 °C of the BTX mixture trapped on AXCav trap and Carbotrap 100®. See http://www.rsc.org/suppdata/nj/b2/b210942e/