Limit of determination in photometric titrations with self-indicating systems

Abstract

An attempt is made to predict the lower limit of concentration (the limit of determination) of a photometric titration based on a self-indicating reaction. When only instrumental factors influence the precision of the result of such a titration it appears to be possible to express the limit of determination in terms of the precision of the absorbance reading and other characteristics of the apparatus (path length and cell volume) and of the reaction (Σε).

The theoretical prediction has been checked by using two commercially available photometers and two reactions, viz., the titration of vanadium(IV) with cerium(IV), and the titration of cerium(IV) with iron(II). The agreement between the theoretically predicted value of the limit of determination and the experimental value appeared to be satisfactory.