Buffers for polarography

Because the polarographic half-wave potentials of certain types of organic compounds depend strongly on the ionic 

In using p.m.r. changes to determine the pA avalues of substituent groups in peptides, and in other pH-dependent measurements of chemical shifts, it is convenient to use acids, bases and buffer species that are lacking in protons. A convenient partial set and the pH (pD) ranges covered are  

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Although there is a wealth of data in the literature on acid-base behavior in aprotic solvents,60 61 there are few examples of the use of buffers for polarography and voltammetry in aprotic solvents. This has occurred because most investigators have sought to keep all potential proton donors out of the system and thereby stabilize anion radicals. Although the picric acid-picrate system has been used as a buffer in a number of studies in aprotic solvents, its use in voltammetric work is limited because of the ease of reduction of picric acid. 

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