Prior to exposure, {HEAD ~ the sorbent} contains {TAIL ~ one or more sorbates} that will desorb during exposure 
contains
Prior to exposure , { HEAD ~ the sorbent } contains { TAIL ~ one or more sorbates } that will desorb during exposure
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH