Such pH monitoring can be automated and the additional base or {TAIL ~ buffer} metered into the aqueous solution as needed to maintain {HEAD ~ the pH} 
Such pH monitoring can be automated and the additional base or { TAIL ~ buffer } metered into the aqueous solution as needed to maintain { HEAD ~ the pH }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD