This construction also allows {TAIL ~ the use} of filters to remove particulates before {HEAD ~ the sample} reaches the chromatographic medium 
This construction also allows { TAIL ~ the use } of filters to remove particulates before { HEAD ~ the sample } reaches the chromatographic medium
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH