A solid-state pH sensor for nonaqueous media including ionic liquids

Authors

Brianna C. Thompson, University of WollongongFollow
Orawan Winther-Jensen, Monash University
Bjorn Winther-Jensen, Monash University,University Of WollongongFollow
Douglas MacFarlane, Monash UniversityFollow

RIS ID

77127

Publication Details

Thompson, B. C., Winther-Jensen, O., Winther-Jensen, B. & MacFarlane, D. (2013). A solid-state pH sensor for nonaqueous media including ionic liquids. Analytical Chemistry, 85 (7), 3521-3525.

Abstract

We describe a solid state electrode structure based on a biologically derived proton-active redox center, riboflavin (RFN). The redox reaction of RFN is a pH-dependent process that requires no water. The electrode was fabricated using our previously described 'stuffing' method to entrap RFN into vapor phase polymerized poly(3,4-ethylenedioxythiophene). The electrode is shown to be capable of measuring the proton activity in the form of an effective pH over a range of different water contents including nonaqueous systems and ionic liquids (ILs). This demonstrates that the entrapment of the redox center facilitates direct electron communication with the polymer. This work provides a miniaturizable system to determine pH (effective) in nonaqueous systems as well as in ionic liquids. The ability to measure pH (effective) is an important step toward the ability to customize ILs with suitable pH (effective) for catalytic reactions and biotechnology applications such as protein preservation.