Effect of bevelling on C1-selective microelectrodes: experimental and model study

Bevelling of the ultra-fine tips of C1-selective microelectrodes (ME) based on liquid ion-exchanger Corning 477913 caused significant decrease in ME resistivity, increase in sensitivity dependent on its initial value and decrease in selectivity constant for bicarbonates (KC1,HCO3) from 10:1 to approximately 8:1. Bevelling did not affect KC1,NO3 which had value below 1 due to higher selectivity of the ion-exchanger for nitrates. The observed experimental alterations in ME behavior after bevelling were in agreement with those predicted by a relatively simple electrical model comprising of two conductive pathways in parallel having opposite in sign sensitivities.