Multi-ion potentiometric sensing becomes challenging for mixed-ion samples in which interfering electrolytes significantly alter the response of each single sensor. Therefore, an emulator based on the phase-boundary potential model is proposed to simulate multi-ion sensing in presence of interference. It serves as investigation tool for understanding the impact of sensor selectivity and interferent ions in the sensor response. Moreover, the emulator is used to design mixed-ion synthetic dataset, following a multi-factorial design of ion mixtures with orthogonal arrays. Such large dataset is suitable for data-intensive learning algorithms used in multivariate calibration of potentiometric sensor arrays.