A recently introduced tuned galvanostatic mode of measurements with ion-selective electrodes (ISEs) is utilized to perform analytical measurements in the nanomolar concentration range with the same or better selectivity than within the traditional ISE working range. Experimental evidence is provided for Ohmic behavior of ISEs when polarized with relatively large currents. Complete unified protocol of the optimization of the compensating current densities for a given ISE in a given solution is presented, as well as the complete unified protocol of analysis of extremely diluted samples. It is also demonstrated that tuned galvanostatic polarization has beneficial effect on the selectivity of ISEs. The problems related to incomplete relaxation of ISEs when the current is shut off are discussed as well. (C) 2013 Elsevier Ltd. All rights reserved.