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