Suitable means include, but are not limited to, the periodic addition of base to {TAIL ~ the aqueous solution} or {HEAD ~ the use} of buffers 
Suitable means include , but are not limited to , the periodic addition of base to { TAIL ~ the aqueous solution } or { HEAD ~ the use } of buffers
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH