Extraction is effected by equilibrating {HEAD ~ homoionically saturated ion exchange resin beads} with {TAIL ~ a sample} of the complex matrix under study 
with
Extraction is effected by equilibrating { HEAD ~ homoionically saturated ion exchange resin beads } with { TAIL ~ a sample } of the complex matrix under study
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH