Hydrophobic laser-induced graphene potentiometric ion-selective electrodes for nitrate sensing

• Published in: Mikrochimica acta (1966) Vol. 189; no. 3; p. 122
• Main Authors: Hjort, Robert G., Soares, Raquel R. A., Li, Jingzhe, Jing, Dapeng, Hartfiel, Lindsey, Chen, Bolin, Van Belle, Bryan, Soupir, Michelle, Smith, Emily, McLamore, Eric, Claussen, Jonathan C., Gomes, Carmen L.
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01.03.2022; Springer; Springer Nature B.V
• Subjects: Analysis; Analytical Chemistry; Aquatic resources; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Contact angle; Electrodes; Environmental protection; Graphene; Graphite; Hydrophobicity; Lakes; Membranes; Microengineering; Nanochemistry; Nanotechnology; Nitrates; Original Paper; Sensors; Stability analysis; Substrates; Surface water; Water quality; Water sampling; Wettability; Agricultural nutrients; Graphene; Water quality; PVC membrane; Ion-selective electrodes (ISE); Potentiometry; Solid contact
• ISSN: 0026-3672; 1436-5073
• DOI: 10.1007/s00604-022-05233-5

Current solid-contact ion-selective electrodes (ISEs) suffer from signal-to-noise drift and short lifespans partly due to water uptake and the development of an aqueous layer between the transducer and ion-selective membrane. To address these challenges, we report on a nitrate ISE based on hydrophobic laser-induced graphene (LIG) coated with a poly(vinyl) chloride–based nitrate selective membrane. The hydrophobic LIG was created using a polyimide substrate and a double lasing process under ambient conditions (air at 23.0 ± 1.0 °C) that resulted in a static water contact angle of 135.5 ± 0.7° (mean ± standard deviation) in wettability testing. The LIG–ISE displayed a Nernstian response of − 58.17 ± 4.21 mV dec −1 and a limit-of-detection (LOD) of 6.01 ± 1.44 µM. Constant current chronopotentiometry and a water layer test were used to evaluate the potential (emf) signal stability with similar performance to previously published work with graphene-based ISEs. Using a portable potentiostat, the sensor displayed comparable ( p  > 0.05) results to a US Environmental Protection Agency (EPA)–accepted analytical method when analyzing water samples collected from two lakes in Ames, IA. The sensors were stored in surface water samples for 5 weeks and displayed nonsignificant difference in performance (LOD and sensitivity). These results, combined with a rapid and low-cost fabrication technique, make the development of hydrophobic LIG–ISEs appealing for a wide range of long-term in situ surface water quality applications. Graphical abstract