Microsensor for simultaneous measurement of H2 and H2S

It is difficult to align chemical profiles measured with different types of microsensors, and it would thus be optimal if one sensor simultaneously can measure two or more parameters. A microsensor for simultaneous measurement of H2 and H2S was constructed by placing a layer of H2S oxidizing ferricyanide in front of a H2 microsensor. The ferrocyanide formed by the H2S oxidation was oxidized by a built-in anode, and the current from this anode was proportional to the H2S concentration at the sensor tip. There was no cross-sensitivity between the two analytes. The sensor was used to measure simultaneous profiles of H2 and H2S in a sediment covered with a dense layer of cyanobacteria.