A λ-MnO2-based graphite–epoxy electrode as lithium ion sensor

The potentiometric response of a λ-MnO2-based graphite–epoxy electrode for the determination of lithium ions was examined. The electrode response to lithium ions was linear in the concentration range 10−6–3.3×10−2 mol/l with a slope of 58.2 mV/decade (at 25°C) over a wide pH range (4–10); no such linear response was found for the ions of other alkali metals or alkaline-earth metals. The logarithm of the selectivity coefficients for Li+ against Na+, K+, Cs+, Mg2+, Ca2+, Sr2+and Ba2+ was found to be −1.5, −2.0, −2.2, −2.0, −2.0, −2.1 and −2.1, respectively. The response time of the proposed electrode was lower than 30 s and its lifetime greater than 6 months.