Abstract
The development of portable sensors that can be used outside the lab is an active area of research in the electroanalytical field. A major focus of such research is the development of low-cost electrodes for use in these sensors. Current electrodes, such as glassy-carbon electrodes (GCEs), are costly and require time-consuming preparation. Alternatives have been proposed, including mechanical pencil-lead electrodes (MPEs). However, MPEs themselves possess numerous drawbacks, particularly structural fragility. In this paper, we present a novel pencil-graphite electrode (PGE) fabricated from a regular HB#2 pencil. This PGE is a simple, disposable, extremely low-cost alternative to GCEs ($0.30 per PGE, vs. $190 + per GCE), and possesses the structural stability that MPEs lack. PGEs were characterized by square-wave voltammetry of ferricyanide, gallic acid, uric acid, dopamine, and several foodstuffs. In all cases, PGEs demonstrated sensitivities comparable or superior to those of the GCE and MPE (LOD = 5.62 × 10−4 M PGE, 4.80 × 10−4 M GCE, 2.93 × 10−4 M MPE). Signal areas and peak heights were typically four to ten times larger for the PGE relative to the GCE.
Highlights
IntroductionThe chemical reactivity of the working electrode (where the reaction of interest occurs) has significant impact on the function of electrochemical sensors
The chemical reactivity of the working electrode has significant impact on the function of electrochemical sensors
pencil-graphite electrode (PGE) derived from mechanical pencil leads (MPEs) have successfully been used to analyze vitamin B12 [18,19], the anti-tapeworm drug niclosamide [20], the copper-chelating properties of flavonoids [2], the hybridization of DNA [21], the anti-cancer drug paclitaxel [22], uric acid and dopamine in urine and blood plasma [23,24,25], glucose [26], an organophosphorus pesticide [27], hydrazine [28], and capsaicin [29]
Summary
The chemical reactivity of the working electrode (where the reaction of interest occurs) has significant impact on the function of electrochemical sensors. In the field of antioxidant research, GCEs have been used to determine the antioxidant capacity of dried vegetable extracts [3], wines [4], fruit and vegetable samples [5,6], blood plasma [7], tea infusions [8], mushroom extracts [9], and standard phenolic and flavonoid solutions [10,11,12]. Building upon previous preliminary characterizations of graphite and pencil electrodes conducted by one of the authors [16], this wooden PGE has been designed to be disposable, simple to fabricate, rapid to use, structurally stable, sensitive, and extremely cost effective; as such this PGE overcomes many of the disadvantages of both GCE and MPE sensors. We hope to establish the developed sensor as a novel, extremely cost-effective, structurally stable and highly sensitive alternative to traditional GCEs and MPEs
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