There is a dearth of base-stable reference electrodes that are suitable for use by students in a teaching laboratory or undergraduate research context. To remedy this, we have developed a technique to produce reference electrodes suitable for alkaline environments. By utilizing components of a commercially available alkaline-type battery, an engineered MnO2/MnO(OH) cathode that is both stable and reproducible is readily obtained. The electrode potentials are quite stable with respect to time and depend on the state of charge of the battery used to make the electrode. The assembly and use of such reference electrodes easily lends itself to introductory electrochemistry lab experiments at a fraction of the cost of traditional electrodes.

An NMR spectroscopic technique has been developed to give rapid, accurate pH measurements on tenth-milliliter samples of concentrated acidic aqueous solutions buffered by fluoride ion in the pH 1.5–4.5 range. The fluoride 19F chemical shift has been calibrated as a function of pH at 0.1 and 1.0 M concentration by reference to an internal 3-fluoropyridine standard. Subsequent measurements of fluoride buffer pH required no additives and only two NMR spectra in the presence of an external reference standard.Graphical abstractResearch highlights▶ Rapid, accurate pH measurement in concentrated aqueous fluoride solutions ▶ δ vs. pH curve calibration via internal and external NMR spectroscopic references ▶ 100 μl sample volume, reusable external reference.