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