{HEAD ~ Fractionation} of a sample reduces the complexity of {TAIL ~ the constituents} of each fraction 
{ HEAD ~ Fractionation } of a sample reduces the complexity of { TAIL ~ the constituents } of each fraction
HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH