A dip-and-read impedimetric electrochemical sensor for orthophosphate monitoring

Phosphorus (P) is an essential element for all life forms and a finite resource. The P cycle in ecosystems plays a vital role in most biological pathways, making it a limiting nutrient. For agriculture, inorganic P is a primary component of fertilizers and is obtained primarily through extractive mining. Excessive application of P fertilizers causes detrimental ecosystem effects such as eutrophication. As a result, there is a pressing need for conservation and management of nutrient loads through analytical techniques to precisely measure orthophosphate in aquatic systems. Here, we test a new two-dimensional sorbent nanomaterial containing graphene oxide and a polyelectrolyte which is known to bind anions (diallyldiethylammonium chloride). The hybrid material is applied for sensing orthophosphate in aqueous samples at what pH range? Geisis worked on pH 8. Laser-induced graphene electrodes were coated with the sorbent nanomaterial. Material analysis was based on zeta potential in different solutions, electron microscopy and X-ray spectroscopic analysis of the electrode coating. Preliminary electrochemical characterization of the functionalized LIG electrode used open circuit potential, cyclic voltammetry, and impedance spectroscopy. After initial characterization, impedance spectroscopy was used as the transduction technique for capacitive sensing of orthophosphate in water samples with a detection limit of 60 ± 5 ppb. Equimolar selectivity assays show the chemsensor was 97% more selective for ortho-P over potassium hydrogen phthalate, bicarbonate, and Tris (a zwitterionic buffer); at least 93% more selective over chloride and nitrate, and at least 87% more selective than sulfate. The developed sensor can be reused after surface regeneration with a regeneration solution (pH 5), and is a low cost sensor platform for scalable development of chemosensors. We have developed first generation mobile phone applications to be used with the sensor for rapid decision support.  

Presentation Preference: Oral

Primary Presenter: Eric McLamore, Clemson University (emclamo@clemson.edu)

Authors:

Geisianny Moreira, Clemson University  (gmonteiromoreira@salud.unm.edu)

Alex Shaw, Arizona State University  (ale2053604@maricopa.edu)

Nafisa Amin, North Carolina State University  (namin3@ncsu.edu)

Wei Gao, North Carolina State University  (wgao5@ncsu.edu)

Eric McLamore, Clemson University  (emclamo@clemson.edu)