Paper as sampling substrates and all-integrating platforms in potentiometric ion determination

Abstract In real-life situations, where samples such as wet soil, body fluids or foodstuff, contain high content of solids/impurities with a limited amount of liquid, sample collection within an adsorptive substrate prior ion determination emerges as a necessary step. For this reason, paper-based technology has been widely studied in development of potentiometric sensors and their application in determination of ions in various samples. Paper is easily available, inexpensive, capable of wicking fluids, disposable and biodegradable, thus provides clear benefits to be integrated with potentiometric ion sensors. In turn, potentiometric ion sensors are characterized by relatively cheap and compact design and, most importantly, by the ability to perform quick and easy ion determination. In this review, all aspects of application of paper substrates in potentiometry will be critically discussed. Those will include the application of paper substrates in paper-based sampling, fabrication of paper-based ion-selective and reference electrodes, and paper-based potentiometric devices.