Peaks corresponding to {HEAD ~ the specified components} in {TAIL ~ the chromatogram} are identified, and presences and absences of these specified components in the sample are thereby determined 
in
Peaks corresponding to { HEAD ~ the specified components } in { TAIL ~ the chromatogram } are identified , and presences and absences of these specified components in the sample are thereby determined
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH