Disposable screen printed potentiometric sensors for determination of free radicals

In this communication new screen printed potentiometric electrodes based on nitrone dispersed in a PVC membrane for the determination of free radicals are reported. Screen printed potentiometric sensors based on an ionophore dispersed in a PVC membrane were previously verified and optimised by using valinomycin as model molecule for potassium ion activity measurement. Valinomycin was used for finding the best deposition condition of the PVC membrane directly on the printed graphite electrodes. Valinomycin containing membranes of different thickness were obtained with "dip & dry" or "tape casting" or "screen printing" techniques by using different dilution of the PVC matrix in tetrahydrofurane (THF). Sensitivity of the valmomicyn based sensors for K+ was found to be strictly related to the thickness of the membrane and the used deposition technique. A very good reproducibility was also observed by comparing the slope values of the calibration curves obtained from several electrodes. Furtherly, nitrone dispersed in the same PVC membrane was used for the development of disposable, screen printed potentiometric sensors for free radicals.