In {HEAD ~ preferred embodiments}, the serum samples are fractionated via {TAIL ~ anion exchange chromatography} 
In { HEAD ~ preferred embodiments } , the serum samples are fractionated via { TAIL ~ anion exchange chromatography }
OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL