Analytical Sciences

Electrochemical Determination of Sulfide at Various Carbon Substrates: A Comparative Study

Jimmy LAWRENCE,* Kay L. ROBINSON,** and Nathan S. LAWRENCE**

*Schlumberger K. K., 2-2-1 Fuchinobe, Sagamihara, Kanagawa 229-0006, Japan
**Schlumberger Cambridge Research, High Cross, Madingley Road, Cambridge, CB3 0EL, UK

The direct electrochemical oxidation of sodium sulfide has been examined at five different carbon-based electrode substrates (glassy carbon (GC), boron-doped diamond (BDD), edge-plane pyrollytic graphite (EPPG), basal-plane pyrollytic graphite (BPPG) and carbon nanotubes (CNT)). An electrocatalytic response is observed at both the EPPG and CNT electrode compared to that of the other three substrates. The higher capacitative charging currents obtained at the CNT electrode hinder its detection range and, as such, the EPPG electrode has been clearly shown to be the substrate of choice for the direct electrochemical detection of sulfide. The procedure was applied to the recovery of a sulfide spike in river water, with a recovery of 104%.

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