The Mediatorless Electroanalytical Sensing of Sulfide Utilizing Unmodified Graphitic Electrode Materials

Bhawana Thakur,Patricia Linton,Shilpa Sawant,Elena Bernalte,Christopher Foster,Jamie Smith,Craig Banks

doi:10.3390/c2020014

Abstract

The mediatorless electroanalytical sensing of sulfide is explored at a range of commercially available graphitic based electrodes namely, edge and basal plane pyrolytic graphite (EPPGE and BPPGE, respectively), boron-doped diamond (BDDE), glassy carbon (GCE) and screen-printed electrodes (SPE). The electrochemical performance is evaluated in terms of current density/analytical signal and oxidation potential, where the GCE and SPE are found to possess the optimal electrochemical responses. The electroanalytical performance of the GCE is explored towards the electrochemical sensing of sulfide and it is found that it is hampered by sulfide passivation, thus requiring pretreatment in the form of electrode polishing between each measurement. We demonstrate that SPEs provide a simple analytically comparable alternative, which, due to their scales of economy, create disposable, one-shot sensors that do not require any pretreatment of the electrode surface. To the best of our knowledge, this is the first report using mediatorless SPEs (bare/unmodified) towards the sensing of sulfide. In addition, the electroanalytical efficacy of the SPEs is also explored towards the detection of sulfide within model aqueous solutions and real drinking water samples presenting good apparent recoveries, justifying the plausibility of this graphitic mediatorless screen-printed platform.

Highlights

Over recent decades, the importance of monitoring the level of sulfide has become an extremely important focus, especially from both environmental and medical diagnostic points of view
Throughout the literature there have been an array of studies for the electroanalytical detection of sulfide within aqueous systems, the majority of these reports focus upon the use of electrocatalysts/mediators for the electrochemical oxidation of sulfide utilizing a variety of molecules, such as ferrocene derivatives, N,N-diethylphenylene-1,4-diamine, catechol and a plethora of others
All the electrochemical measurements consisted of a three electrode system with a range of working electrodes: glassy carbon electrode (GCE, 3 mm diameter), edge plane pyrolytic graphite electrode (EPPGE, 4.9 mm diameter), basal plane pyrolytic graphite electrode (BPPGE, 4.9 mm diameter) or boron doped diamond electrode (BDDE, 3 mm diameter), a nickel wire counter and a saturated calomel electrode (SCE) reference electrode to complete the circuit

Summary

Introduction

The importance of monitoring the level of sulfide has become an extremely important focus, especially from both environmental and medical diagnostic points of view. There are several methods reported within the literature for the analytical sensing of sulfide (within aqueous media) such as chromatography, mass spectrometry, fluorescent and chemiluminescent techniques [2,3,4,5,6,7], electroanalytical techniques can provide potentially sensitive, portable and low cost alternatives [8,9,10,11,12,13]. There have been several reports upon the electroanalytical sensing of sulfide within aqueous media, many involve multiple arduous and time-consuming fabrication steps. C 2016, 2, 14 and in the majority of these reports, electrocatalysts/mediators are employed for the electrochemical sensing of sulfide; Table 1 provides a thorough overview of literature. Screen-printing technology permits the mass production of highly reproducible electrode configurations and, due to its scales of economy, inexpensive electrochemical sensing platforms can be readily fabricated [19,20,21]

Methods

Results

Conclusion