detect H2S in your sample

Unisense H2S-10The H2S microsensor is a reliable tool for studying H2S production in a wide range of applications. Tip size can be made as small as 2-3 µM for high spatial resolution of H2S microprofiles. This combined with a fast response time of down to 0,3 seconds makes the H2S microsensor a high quality instrument for H2S investigations.

The H2S microsensor can be applied in a broad variety of research fields where non-destructive, fast and accurate measurements are required. The H2S microsensor is designed for research applications within:

  • Environmental sciences
  • Biomedical sciences
  • Biotechnology
  • Microbiology

Download Unisense Microsensors Brochure


microsensor technology

PageLines-UnisenseOX-MR.jpgThe Unisense H2S microsensor is a miniaturized amperometric sensor with an internal reference, a sensing and a guard anode. The anodes are polarized against an internal reference. Driven by the external partial pressure, H2S from the environment penetrates through the sensor tip membrane into the alkaline electrolyte, where the HS ions formed are oxidized immediately by ferricyanide, producing sulfur and ferrocyanide.

The sensor signal is generated by re-oxidation of ferrocyanide at the anode in the tip of the sensor (Jeroschewski et al. 1996). The resulting sensor signal is in the pA range and is measured by a high quality picoammeter e.g. the Unisense Microsensor Multimeter. The internal guard electrode is polarized to scavenge H2S and facilitates  a constant ratio of ferri- to ferrocyanide in the electrolyte, thus minimizing the zero-current.

To calculate total sulfide concentrations, it is also required to measure the pH in the sample.


part numbers and outside tip diameter

  • Unisense OX-NH2S-10: 8-12 µm
  • H2S-25: 20-30 µm
  • H2S-50: 40-60 µm
  • H2S-100: 90-110 µm
  • H2S-500: 400-600 µm
  • H2S-MR: 400-600 µm
  • H2S-N: 1.1 mm
  • H2S-NP: 1.6 mm – needle sensor for piercing
  • H2S-Eddy: 15-25 µm



Download Detailed H2S Microsensor Spec Sheet



Hydrogen Sulfide Sensor Manual



Jeroschewski,P. et al (1996), An Amperometric Microsensor for the Determination of H2S in Aquatic Environments, Anal Chem, 4351 – 4357, vol. 68

Stachowitsch,M. et al (2007), Oxygen depletion and benthic mortalities: the first in situ experimental approach to documenting an elusive phenomenon, Limnology and Oceanography: Methods, 344 – 352, vol. 5

Mohanakrishnan,J. et al (2008), Nitrite effectively inhibits sulfide and methane production in a laboratory scale sewer reactor, Water Research, 3961 – 3971, vol. 42


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