Monitoring acid-base, precipitation, complexation and redox titrations by a capacitively coupled contactless conductivity detector

Abstract

Herein, an approach for versatile titration by monitoring the chemical reaction process with a developed capacitively coupled contactless conductivity detector (C4D) was developed. A disposable glass reaction cell, in which sub-milliliter titrand was loaded, was inserted into the working head stage of the C4D. Upon addition of titrant, the ionic strength and/or mobility of components in the solution changed, causing consequently change of conductivity. The C4D monitored the change in real time. A V-shaped titration curve was gained, allowing an easy identification of the endpoint. Between the elapsed time and the initial concentration of titrand, linear relationships were found for classical acid-base, precipitation, complexation and redox reaction over certain ranges, enabling the establishment of quantitative determinations. The new approach had a few charming advantages (e.g. simplicity and cost effectiveness) over contact electrochemical methods because that the solution was isolated from the working electrodes. Therefore, a development of versatile and multifunctional platform for micro-titrations is promising.