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H2S Microsensor

Detect H2S in your sample

The H2S microsensor is a reliable tool for studying H2S production and oxidation in a wide range of applications. Tip size can be made as small as 10 µm for high spatial resolution of H2S microprofiles. This combined with a fast response time of down to <10 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
  • Biogeochemistry

Microsensor technology:

Unisense offers two types of H2S microsensors with different characteristics. Both types are miniaturized amperometric sensors with internal reference and a sensing anode. The anode is polarized against an internal reference. Driven by the external partial pressure, H2S from the environment penetrates through the sensor tip membrane into the electrolyte where the H2S is ultimately oxidised by the anode. This generates a current in the pA range which is measured by a high quality picoammeter e.g. the Unisense Microsensor Multimeter.

In the type I sensor (Sulf-xxx) the signal is generated by oxidation of H2S directly on the anode in the tip of the sensor. The type I sensor is sensitive to hydrogen and should not be used in environments with high hydrogen concentrations. However, the type I sensor has a higher signal to noise ratio, has a longer warranty and expected lifetime than the type II sensor and is not sensitive to light.

The type II (H2S-xxx) sensor is a customized sensor for samples containing H2. In the type II sensor (H2S-xxx) the H2S, that enters through the membrane in the tip, is converted to HS- ions in the alkaline electrolyte. This is immediately oxidized 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 internal guard electrode facilitates a constant ratio of ferri- to ferrocyanide in the electrolyte, thus minimizing the zero-current. The ferri-/ferrocyanide complex is light sensitive and the sensors are painted black to minimize light interference.
Type II H2S-xxx is made against a 10% customization fee compared to the equivalent SULF-xxx.

The type I sensor should be chosen in most environments because of higher signal to noise ratio and longer expected lifetime. If hydrogen is present in significant concentrations type II should be used.

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


Jeroschewski, P., C. Steuckart, and M. Kühl. 1996. An amperometric microsensor for the determination of H2S in aquatic environments. Anal. Chem. 68: 4351–4357.

Ordering Information

Standard Glass Sensor
(SULF-xxx or H2S-xxx)

Outside tip diameter
(tip size and description)
SULF-10 H2S-10 8-12 µm
SULF-25 H2S-25 20-30 µm
SULF-50 H2S-50 40-60 µm
SULF-100 H2S-100 90-110 µm
SULF-200 H2S-200 175-225 µm
SULF-500 H2S-500 400-600 µm
SULF-MR H2S-MR 400-600 µm
SULF-N H2S-N 1,1 x 40 mm - needle sensor
SULF-NP H2S-NP 1,6 x 40 mm - needle sensor for piercing
SULF-Eddy H2S-Eddy 40-60 µm - for Edddy Correlation
SULF-50LR H2S-50LR 40-60 µm - needle sensor for piercing
and for low concentration range
SULF-100LR H2S-100LR 90-110 µm - for low concentration range
SULF-500LR H2S-500LR 400-600 µm - for low concentration
range applications
SULF-NPLR H2S-NPLR 1,6 x 40 mm - needle sensor for piercing
and for low concentration range

Find complete hydrogen sulfide microsensor specifications, including warranty and expected life time, below and possible microsensor customizations and adaptations under Related Products found to the right.

View SULF sensor specifications

View H2S sensor specifications

Technical information

View SULF sensor specifications

View H2S sensor specifications

Chemical Interferences Specs.

H<sub>2</sub>S Calibration Kit Video

H2S Calibration Kit Video

This video guides you through the calibration of a Unisense Sulf/H2S Sensor using our Sulf/H2S Calibration Kit. 

Watch Video Guide

Related products

Sensor customization

Raggio, Rosasilvia et al (2018), Silk Fibroin Porous Scaffolds Loaded with a Slow-Releasing Hydrogen Sulfide Agent (GYY4137) for Applications of Tissue Engineering, ACS Biomaterials Science and Engineering, 2956 - 2966, vol. 4 Read abstract

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

Stachowitsch, Michael 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 Read abstract

Jeroschewski, Paul et al (1996), An Amperometric Microsensor for the Determination of H2S in Aquatic Environments, Analytical Chemistry, 4351 - 4357, vol. 68 Read abstract

See all publications
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