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Photo-potentiometry: Sensing of sugars using a pH-probe coated with a film of intrinsically microporous polyamine containing graphitic carbon nitride photocatalyst

Fernanda C O L Martins, Wanessa R Melchert, Mariolino Carta Orcid Logo, Neil B McKeown, Frank Marken

Talanta, Volume: 296, Start page: 128461

Swansea University Author: Mariolino Carta Orcid Logo

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DOI (Published version): 10.1016/j.talanta.2025.128461

Abstract

At proof-of-concept level, the photochemical transformation of glucose (or more generally of carbohydrates) can be detected analytically as a localised pH change. Using a conventional potentiometric pH-probe, a microporous coating is developed to explore carbohydrate sensing in the 200-800 μM concen...

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Published in: Talanta
ISSN: 0039-9140 1873-3573
Published: Elsevier BV 2026
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URI: https://cronfa.swan.ac.uk/Record/cronfa69905
Abstract: At proof-of-concept level, the photochemical transformation of glucose (or more generally of carbohydrates) can be detected analytically as a localised pH change. Using a conventional potentiometric pH-probe, a microporous coating is developed to explore carbohydrate sensing in the 200-800 μM concentration range based on localised pH changes induced by light. The photo-responsive film is based on fibrous cellulose (to aid permeability), photocatalytic graphitic carbon nitride (g-C N ), and an intrinsically microporous polyamine host (PIM-EA-TB, as reaction environment and binder). The film-modified pH-probe is pre-conditioned in a pH 4 buffer (containing phthalate buffer). When immersed in an aqueous solution, switching on a blue LED (λ = 385 nm, approx. 60 mW cm ) causes a pH transient towards alkaline, which is correlated with the carbohydrate concentration (all three glucose, fructose, or sucrose give very similar signals). The LOD is typically 70 μmol dm , with a linear range up to 800 μmol dm . Non-linearity beyond 800 μmol dm is tentatively attributed to limited oxygen availability. The photo-electroanalytical mechanism is discussed in terms of competing proton generation and consumption in the photoactive film linked to oxygen depletion (causing alkaline drift) at the pH-probe surface.
Keywords: Photo-electroanalysis; Chronopotentiometry; Photo-pH-probe; Carbohydrates; Sugary drinks
College: Faculty of Science and Engineering
Funders: F.C.O.L. Martins and W.R. Melchert acknowledge the financial support from Brazilian Government Agencies, including the Brazilian National Council for Scientific and Technological Development (CNPq, grants 305538/2022–5) and, in part by the Coordination of Superior Level Staff Improvement (CAPES) - Finance Code 001. F. Marken acknowledges initial funding from EPSRC (EP/K004956/1).
Start Page: 128461

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