A conductometric sensor for potassium detection in whole blood

This work presents a new sensor for potassium determination based on interdigitated conductometric thin-film planar electrodes. It was fabricated by including valinomycin in a plasticized PVC membrane deposited on the sensitive area of the transducer. The potassium sensor presents a detection limit of 0.03 mM in 5 mM phosphate buffer electrolyte and a detection limit of 0.01 mM in a 5 mM phosphate buffer prepared in a 600 mM sucrose solution, due to decrease of the background conductivity. Dynamic ranges were respectively 0.1 mM-16 mM and 0.1 mM-8 mM. After dilution of artificial blood in 600 mM sucrose solution, it was possible to detect blood potassium concentration, using the conductometric sensor. It has been shown that the presence of sucrose prevents red cell lysis through maintaining a high osmolarity.