Determination of benzalkonium chloride preservative in pharmaceutical formulation of eye and ear drops using new potentiometric sensors

► A new approach for determination of low concentrations of the BCCl preservative in eye and ear drops is presented. ► New modified carbon paste electrodes for benzalkonium chloride were designed. ► The limit of detection of the developed electrodes are 1.0 × 10− 7 M and 1.6 × 10− 7 M with short response time ~ 5-8 s. ► Electrodes showed accurate and reproducible detection of BCCl in preparations as eye and ear drops.