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