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