Determination of water by flow injection analysis using Karl Fischer reagent with electrochemical detection

Abstract

The determination of water in organic samples has been investigated using flow injection analysis and pumped sample segmented flow analysis. Karl Fischer solution was the active reagent and both amperometric and potentiometric detection systems were studied. Various electrode combinations and cell configurations were tried for the two detection methods. The best performance was obtained with a potentiometric system using a platinum indicating electrode and a calomel or silver reference electrode. This system was automated with a positive-pressure HPLC autosampler. A linear working range of 0–1500 p.p.m. was obtained with a 50-µl sample volume and methanol or methanol-xylene carrier streams. The method has a maximum sample frequency of 60 h^–1 and has been used for the analysis of gasoline-alcohol blends.