Nuclear chemistry

Electrochemistry

Materials science

Chromatography

Inorganic chemistry

Electrochemical gas sensor

Physical chemistry

Redox

Organic chemistry

Graphite

Linear range

Amperometry

Analytical Chemistry (journal)

Cobalt

Chemistry

Electrode

Detection limit

Overpotential

Sensors and Actuators B Chemical

A chemically modified amperometric sensor was constructed by mechanically immobilizing cobalt hexacyanoferrate onto the surface of a paraffin impregnated graphite electrode (PIGE). The cyclic voltammogram of the electrode exhibited two reversible redox peaks corresponding to Co2+/Co3+ and Fe(CN)64−/Fe(CN)63− reactions. Thiosulphate was found to undergo electrocatalytic oxidation at a reduced overpotential with good sensitivity in a wider pH range at the modified electrode. The sensor showed good stability and reproducibility. Under optimal condition, the sensor showed a linear response for thiosulphate in the concentration range from 4×10−5 to 4.8×10−4 M with a correlation coefficient of 0.9972 and the detection limit was 1.8×10−5 M (S/N=3). The sensor has been applied for the determination of thiosulphate in the photographic effluents.

Amperometric sensor for thiosulphate based on cobalt hexacyanoferrate modified electrode