A method of use includes contacting an analyte and a preconcentrator, allowing {HEAD ~ the analyte} to adsorb to {TAIL ~ the preconcentrator} and then desorbing the analyte 
A method of use includes contacting an analyte and a preconcentrator , allowing { HEAD ~ the analyte } to adsorb to { TAIL ~ the preconcentrator } and then desorbing the analyte
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH