Abstract
A novel paper-based potentiometric platform for the simple and fast monitoring of water hardness is presented. First, potentiometric ion-selective electrodes for calcium and magnesium printed on a paper substrate were built and optimized. These sensors, which display near-Nernstian sensitivity, were used for the determination of the concentration of these cations and the calculation of the water hardness. Second, the incorporation of a solid-state reference electrode allowed building an integrated paper-based potentiometric cell for the determination of the hardness of artificial and real samples (mineral waters). The validation of the results shows good ability to predict hardness in the conventional scale. Truly decentralized measurements were demonstrated by integration of a miniaturized instrument and dedicated software in a portable device. The measurements were able to be performed in just under two minutes, including a two-point calibration. Since the method is simple to use and cost-effective, it can be implemented in domestic and industrial settings.
Highlights
Water quality has a direct impact on natural and physiological processes as well as in human activities
One of the main reasons that drives the interest on water hardness is the low solubility of many Ca2+ and Mg2+ salts, such as carbonates, sulphates or phosphates, which leads to problems with a significant economic impact
We introduce for the first time a complete, paper-based potentiometric cell for the determination of water hardness
Summary
Between two adhesive plastic masks (ARCare 8259, Adhesives Research, Inc., Glen Rock, PA, USA), one of which has orifices that leave the conductive material exposed. This orifice (radius = 1.5 mm) is the electroactive window. The membrane cocktail (15 μL) was drop-cast onto the carbon-ink paper. In order to build the working electrodes, 15 μL of the membrane cocktail were drop-cast onto the electroactive window (Figure 1a) while the Ag/AgCl ink-based paper substrate was used for the reference electrode (Creative Materials, Inc., Ayer, MA, USA). (Figure 1a) while the Ag/AgCl ink-based paper substrate was used for the reference electrode (Creative Materials, Inc., Ayer, MA, U.S.A.).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
