Preparation of Phosphate Ion-Selective Membrane Based on Silver Salts Mixed with PTFE or Carbon Nanotubes

Abstract

A sensitive phosphate sensor has been prepared by constructing a solid membrane disk consisting of variable mixtures of silver phosphate, silver sulfide, and PTFE (Type 1 membrane) or silver phosphate, silver sulfide and nanotube (Type 2 membrane). The ternary membranes exhibit greater selectivity over the wide range of concentration. The membrane with the composition of 50.00% PTFE; 41.66% Ag 3 PO 4 and 8.33% Ag 2 S was selected as our preferred membrane. The membranes exhibited linear potential response in the concentration range of 1×10 -1 to 1×10 -5 M. Their detection limit is about 5×10 -6 M. The membranes have a long lifetime and can be stored in air when they are not in use. The best performance for nanocomposite sensor was obtained with membrane of the following composition: 78.00% Ag 3 PO 4 ; 20.00% Ag 2 S, and 2.00% carbon nanoparticles. The membrane had a slope of 32.6 mV toward HPO 4 2ions in the range between 1×10 -1 and 1×10 -5 M with a detection limit of 5.45×10 -6 M. The proposed sensors were found to be applicable over a pH range between 3 and 7.

Potentiometric Response of Solid-State Sensors Based on Ferric Phosphate for Iron(III) Determination

“…Membranes M11–M15 show the importance of the presence of silver sulfide and polytetrafluoroethylene. A similar approach was previously reported [ 4 , 5 , 27 , 28 ]. As described, 15 different membranes were prepared and their composition ratios are shown in Table 1 .…”

Review—Solid State Sensors for Phosphate Detection in Environmental and Medical Diagnostics

“…Another electrode was fabricated using a mixture of silver phosphate and silver sulfide with polytetrafluoroethylene (PTFE) or carbon nanotube (CNT). 28 The active materials were mixed, and the membrane was formed by pressing the mixture at 700 MPa for 1.5-2 h at room temperature. The membrane prepared with CNT improved the sensor sensitivity from 21 mV decade −1 (without CNT) to 32.6 mV dec −1 with CNT at pH 9.2.…”

“…Tributyltin chloride was used for real time monitoring of H 2 PO 4 − intake by plants. 28 The sensor was used for continuous monitoring of phosphate in the growth media at pH 5.8 for 15 d. The sensor response was linear between 5.6 × 10 −6 to 1.6 × 10 −2 M and a sensitivity of −55.6 mV dec −1 and limit of detection 2.14 × 10 −6 M. However, the sensor required six hours conditioning in KH 2 PO 4 solution (10 −6 M) before measurements. A recent sensor used copper doped co-polymer and CNT to detect HPO 4 2 − within a pH range of 7.0-9.5.…”

A Novel Reduced Graphene Oxide Modified Carbon Paste Electrode for Potentiometric Determination of Trihexyphenidyl Hydrochloride in Pharmaceutical and Biological Matrices

“…In the literature, there is only one work on the determination of THP using a carbon paste electrode [ 5 ]. Since nanomaterials are playing an increasingly important role in the fabrication of chemo- and bio-sensors [ 24 , 31 , 47 , 48 , 49 , 50 ] due to the possibility of their direct and easy incorporation into ion-selective membranes, synthesized reduced graphene oxide (rGO) was used in this work. A sensor for the determination of THP containing any type of nanomaterials has not yet been developed according to the available literature.…”