Monograph - Metrohm

Preface1 PrefaceNon-aqueous titrations continue to play an important role in analysis, no matterwhether in the determination of acid or base numbers in oils and fats, for quantifyingproducts with different acidic or basic strengths separately or for titratingsubstances that are insoluble in water.This monograph is not intended to be a textbook; it should rather help the practicalchemist to decide which solvents, electrodes, titrants and instruments are themost suitable ones for the particular application. The monograph makes no claimto be complete; it also assumes a certain basic knowledge of potentiometricanalysis.Non-aqueous titrations are not without their problems. Effects are experiencedthat do not occur in this form in purely aqueous systems. The main problems are:a) interferences caused by static electricity andb) the response behaviour of the electrodes used.As far as a) is concerned a wide range of different measures have already beenintroduced or at least tried. These include everything from titration in earthedsolutions through shielding the complete titration system (Faraday cage) and upto the use of differential amplifiers and the three-electrode technique. This lattertechnique has its advantages in many cases, above all wherever work is carriedout in nonpolar solvents with nonpolar samples (e.g. petrochemical products).The type of electrode(s) used also plays a major role, which brings us to point b).Many years of experience involving non-aqueous titration have resulted inMetrohm developing a special electrode that is particularly suitable for non-aqueoustitration – the 6.0229.100 Solvotrode. It meets all the demands that must beplaced on such an electrode: large membrane surface, as small a membraneresistance as possible, rapid response, optimally designed ground-joint diaphragm,excellent shielding and appropriate electrolyte solutions.Non-aqueous titration of acids and bases with potentiometric endpoint indication 3