While the exclusion of sodium has received {HEAD ~ the most attention} because of its ubiquitous presence and high mobility, the other alkali metal ions, especially potassium and {TAIL ~ lithium}, are also desirably kept to acceptable levels 
While the exclusion of sodium has received { HEAD ~ the most attention } because of its ubiquitous presence and high mobility , the other alkali metal ions , especially potassium and { TAIL ~ lithium } , are also desirably kept to acceptable levels
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH