Buffer pair definition

By definition, a buffer solution resists changes in pH with dilution or with addition of acids or bases. Generally, buffer solutions are prepared from a conjugate acid/base pair, such as acetic acid/sodium acetate or ammonium chloride/ammonia. Chemists use buffers to maintain the pH of solutions at a relatively constant and predetermined level. You will find many references to buffers throughout this text. 

When electrodes are manufactured, every practical attempt is made to minimize this area. Electrodes that do not meet an asymmetry potential specification are eliminated. The asymmetry potential, in this case, is any difference in potential between glass and SCE reference electrodes, when immersed in pH 7 buffer (see Section 3.1.4 for an exact definition). Since it is not possible to obtain an isopotential point with electrodes, the pH meter isopotential point is set at the most likely point, pH 7. Since this point is only an estimation of the electrodes isopotential point, a slight error is observed if the measuring temperature is different than the buffering temperature. This is because a change in the slope made by changing the temperature compensator of the meter may not revolve around the same point as the slope of the electrode pair. 

Determination of Meter Readings for the Nonaqueous Btqfer Solutions Corresponding to Acid End Points—To ensure comparable selection of end points when definite inflection points are not obtained in the titration curve, determine daily, for each electrode pair, the meter readings obtained with freshly prepared nonaqueous acidic and basic buffer solutions. 

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