 from {HEAD ~ about 10 mole percent} to about 25 mole percent of {TAIL ~ the ampholytic ion pair} 
from { HEAD ~ about 10 mole percent } to about 25 mole percent of { TAIL ~ the ampholytic ion pair }
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL