The highest sensitivity was found for the type B electrode (electrochemically
oxidized W rod in 0.1 mol dm3 H2SO4) amounting
to 49.5 ± 2.3 mV per pH unit, with R2 = 0.99, which agrees well
with the previous reports on the sensitivity of tungsten based pH
sensors in air-saturated buffer solutions [26,30,43]. The electrodes
type A (electrochemically polished W rod in 0.1 mol dm3 KOH)
and C (aged W rod in 0.1 mol dm3 KOH) displayed lesss atisfactory slope, as well as a scatter of points.