The application of organic salt modified paper substrates in potentiometric determination of ions in aqueous enviromental samples

• Main Author: Abdul Salim Fazal Karim
• Other Authors: Grzegorz Lisak
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2020
• Subjects: Engineering::Environmental engineering
• Online Access: https://hdl.handle.net/10356/140661
• Institution: Nanyang Technological University

Paper substrates were modified with different organic salts and used in microfluidic paper-based sampling for the determination of heavy metals, such as lead(II) (Pb2+) by combining the microfluidic paper-based sampling with potentiometric ion sensors (ion-selective electrodes, ISEs). The Cl- ion was further investigated to compare different effects of organic salt modifications on different ion selective membranes (ISMs). The paper based microfluidic sampling integrated with potentiometric ion sensing were characterized by the unwanted super Nernstian response for paper substrates without organic salt pretreatment and desirable standard Nernstian response for paper substrates with organic salt treatment. The chemical reaction and physical processes between the metal ions, sample solutions and paper substrates were reduced with the usage of the pre-treated paper substrates. Nevertheless, to sustain Nernstian response of sensors, a fairly high concentrations of organic salts for the pre-treatment of paper substrateswere required. A few organic salts were selected for this study namely tridodecylmethylammonium chloride, potassium tetrakis [3.5-bis(trifluoromethyl)phenyl] borate and tetradodec tetrakis (4-cholorophenyl) borate. It was found that paper substrate pre-treated with potassium tetrakis [3.5-bis(trifluoromethyl)phenyl] borate was able to eliminate the super Nernstian response registered in Pb(NO3)2 solutions when using Pb2+-ISEs. This work opens new chapter in paper modifications to allow measurements of ions in low liquid and high solid content samples. I