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