Fabrication of a Phosphate Ion Selective Electrode Based on Modified Molybdenum Metal

Abstract

A phosphate ion-selective electrode using molybdenum metal was constructed. The modified molybdenum electrode responded to HPO4 2in the presence of molybdenum dioxide and molybdophosphate (PMo12O40 3-) on the surface. The electrode exhibited a linear response to HPO4 2in the concentration range between 1.0 × 10 -5 and 1.0 × 10 -1 M (mol dm -3 ) in the pH range from 8.0 to 9.5 with a detection limit of 1.0 × 10 -6 M. The sensor showed near Nernstian characteristics (27.8 ± 0.5 mV dec -1 ) at pH 9.0. Since the responding potential was attributed to the activity of HPO4 2-, the potential at a given concentration of phosphate depended on the pH. The electrode indicated a good selectivity with respect to other common anions such as NO3 -, SO4 2-, Cl -, HCO3and CH3COO -. The modified molybdenum electrode can be continuously used for over a 1 month with good reproducibility. The feasibility of the electrochemical sensor was proved by successful for the detection of phosphate in real samples.

Electrochemical Mechanisms in Potentiometric Phosphate Sensing Using Pure Cobalt, Molybdenum and their Alloy for Environmental Applications

“…The Mo CV (Figure 4c) showed an anodic peak at −0.43 V which is Mo oxidation (Eq 11), facilitated by the reaction of Mo m O n z− and HPO 4 2− (Eq 12). Similar results were also reported in other studies [13e].…”

“…Unlike Co and Mo indicator electrodes, Co 63 Mo 37 (Co 63 wt%, Mo 37 wt%) alloy showed a significant increase ( p <0.05) in Emf values with phosphate concentration (Figure 2). Other work reported similar results on Co and Mo phosphate sensing electrodes, where the oxidation of Mo and Co was enhanced with phosphate concentration leading to a decrease of Emf with phosphate concentration [13a, d, e].…”

“…From previous research and the literature review, it was shown that Co‐based electrodes have the highest selectivity towards acidic phosphate species, H 2 PO 4 − , [13b, f, 14d, 15] which occurs at pH range 3 to 6 (Figure 1). More recently, Mo was introduced to P potentiometric sensing [13d, e]. Under alkaline conditions, Mo produced an intermediate substance and continued to react with hydrogen phosphate (HPO 4 2− ) and phosphate (PO 4 3− ) [13d, e].…”

“…More recently, Mo was introduced to P potentiometric sensing [13d, e]. Under alkaline conditions, Mo produced an intermediate substance and continued to react with hydrogen phosphate (HPO 4 2− ) and phosphate (PO 4 3− ) [13d, e]. Unlike Co, Mo showed an effective selectivity towards alkaline phosphate ion groups (HPO 4 2− , PO 4 3− ) occurring at pH >6.5 (Figure 1).…”

A Green Chemosensor for Colorimetric Determination of Phosphate Ion in Soil, Bone, and Water Samples Using Curcumin Nanoparticles

“…Consequently, the determination of phosphate in natural waters is a priority for checking and controlling the water quality. 1,2 Owing to the importance of phosphate determination, to date, several analytical methods have been employed for the assay of phosphate, including spectrophotometry, 1,3,4 microcomplexationspectrophotometry, 5 solid phase extraction spectrophotometry, 6 electrochemistry, 7,8 micro nuclear magnetic resonance spectroscopy (NMR), 9 flow injection analysis (FIA), 10 near-infrared, 11 spectrofluorimetry, 12,13 paper-based analytical devices, 14 ion chromatography, 15 and high-performance liquid chromatography mass spectrometry (HPLC-MS/MS). 16 Compared to other techniques described above, UV-Vis spectrophotometric methods are still known as an attractive alternative because of rapidity, simple instrumental implementation, versatility and availability of the instrumentation.…”