Peak Width and Gradient Titrations

4 Peak Width and Gradient Titrations Peak Width Measurement 

It might appear that peak width merely serves as range extension. Yet, since peak width is related to a time span, which in turn is related through linear flow velocity to volumetric rate, peak width measurements allow flow titrations to be performed in a novel way. Therefore, similarly to classical batch titrations, FIA titrations encompass a domain of determinations, which cannot be performed in any other way, because they are based on consumption of an equivalent amount of reagent and, therefore, titrations yield different information than a direct measurement (pH measurement versus titration of a mixture of a weak and strong acid). 

However, further studies have shown that the injection process itself conforms with the one-mixing-stage model, and this observation allowed miniaturization and simplification of the FIA system, resulting in elimination of the mixing chamber and implementation of high-speed titrations [183]. Such titrations are performed at medium or even limited dispersion. A detailed treatment of dispersion in a one-tank system for small D values, recently developed by Tyson [1062], requires a modification of const, so that for low D values 

According to this equation, the detection limit for a single-line system (cf. Fig. 2.13) occurs when the equivalence condition is met 

Technically, FIA titrations can be performed either in a single-line system, as discussed previously, or in a two-line system (cfr. Fig. 2.14 and Section 4.9.). For a two-line system, where titrant R is confluenced to a sample zone dispersed in an inert carrier stream. 

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