Use of multivariate data analysis was beneficial even in case of arrays composed of only 3 valinomycin based sensors -the same used to construct the calibration curve, which indicates that performance of many systems, also commercial ones might be enhanced by simple adjustment of the regression parameters. Direct quantification based on the calibration curve was only better than the RF model in case of one pharmaceutical supplement (ZiNIQ+ Electrolites -Tab. SI1) Fig. Prediction of potassium for real samples using a Random Forest algorithm -red stars compared to use of valinomycin ISE calibration curve -black circles.