amines and amine derivatives that improve the buffering range , and / or reduce the chelation and other negative interactions of the buffer and the system to be buffered . the reaction of amines or polyamines with various molecules to form polyamines with differing pka &# 39 ; s will extend the buffering range , derivatives that result in polyamines that have the same pka yields a greater buffering capacity . derivatives that result in zwitterionic buffers improve yield by allowing a greater range of stability .