SULF-50
H2S black tip
MR sensor
Needle sensor
fx-6 UniAmp
Designed for research applications within:
Environmental Sciences
Biomedical Sciences
Biotechnology
Microbiology
Biogeochemistry

H2S microsensor

Detect H2S in your sample

You can choose the H2S microsensor with a tip size down to 10 µm for high spatial resolution of H2S microprofiles, and with a fast response time of down to <10 seconds, you get a reliable tool for studying H2S production and oxidation. Read more...

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Technical Data
Chemical Interferences
Ordering Information & Sizes
Adaptations
Manuals & Videos
H2S Microsensor

Two types of H2S microsensors

Unisense offers two types of H2S microsensors with different characteristics, SULF and H2S.

Both types are miniaturized amperometric sensors with a sensing anode 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, such as the UniAmp Multi Channel.

Read more about the our two different types of H2S microsensors below.

H2S in biofilm_700x480

Which H2S sensor should you choose?

The type 1 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 2 should be used.

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

Type 1: SULF sensor

In the type 1 sensor (SULF), the signal is generated by oxidation of H2S directly on the anode in the tip of the sensor. The type 1 sensor is sensitive to hydrogen and should not be used in environments with high hydrogen concentrations. However, the type 1 sensor is not sensitive to light, and it has a higher signal-to-noise ratio. Additionally, you get a longer warranty and expected lifetime.

Type 2: H2S sensor

The type 2 (H2S) sensor is a customized sensor for environments containing H2. In the type 2 sensor (H2S-xxx), the H2S enters through the membrane in the tip and 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 (see 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 coated black to minimize light interference.

Type 2 H2S is made against a 10% customization fee compared to the equivalent SULF.

Reference

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

SULF type I_700x480 H2S type II_700x480
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Type 1: SULF
Type 2: H2S
General
Cables & Connectors
Characteristics
Stirring Sensitivity & Response Time
General
Feature Standard Options Extra price for option selection
Total length 150-200 mm 70-350 mm 20-50%
Diameter 20 mm from tip < 2 mm < 1 mm 10%
Diameter 50 mm from tip 8 mm < 2 mm 20%
Glass shaft diameter 8 mm
Plastic shaft protection diameter* 11 mm Can be omitted

*When mounted with in situ mini connectors, the shaft has no protection mounted, but fits directly into the in situ sensor mounts with pressure compensation. In situ sensors have a standard length of 130-160 mm.

Cables & Connectors
Item Standard Options Extra price for option selection
Cable Habia
Cable length 1.5-2 m 0-20 m Yes, depends on length
Connector LEMO BNC adaptor Yes, order separately
In situ gold pin connector* No Yes

*When mounted with in situ mini connectors, the shaft has no protection mounted, but fits directly into the in situ sensor mounts with pressure compensation. In situ sensors have a standard length of 130-160 mm.

Characteristics
Attribute Standard Options Extra price for option selection
Guaranteed lifetime 6 months
Expected lifetime > 1 Year
Temperature range -2-60°C, tip only
Temperature coefficient 2-3% per °C
Range About 0-300 µM H2S in water 0-10 mM 20%
Linear range About 0-300 µM H2S in water | About 0-10 µM for LR (Low Range) sensors | About 0-1 µM for Ultra LR sensors 0-10 mM 20%
Detection limit 0.3µM | Low Range sensors 10 nM 2-3 nM (only for 200µm and 500µm tip sizes) 20%
Internal reference Yes
Waterproof Yes
Pressure tolerant sensing tip Yes
Spatial resolution Equals outside tip diameter
Signal drift 25% per month
Stirring Sensitivity & Response Time
Item Stirring sensitivity Response time (90%) Extra price
SULF <2% <10 s | <20 s on Low Range sensors | <60 s on optional 2-3 nM sensors
General
Cables & Connectors
Characteristics
Stirring Sensitivity & Response Time
General
Feature Standard Options Extra price for option selection
Total length 150-200 mm 70-350 mm 20-50%
Diameter 20 mm from tip < 2 mm < 1 mm 10%
Diameter 50 mm from tip 8 mm < 2 mm 20%
Glass shaft diameter 8 mm
Plastic shaft protection diameter* 11 mm Can be omitted

*When mounted with in situ mini connectors, the shaft has no protection mounted, but fits directly into the in situ sensor mounts with pressure compensation. In situ sensors have a standard length of 130-160 mm.

Cables & Connectors
Item Standard Options Extra price for option selection
Cable Habia
Cable length 1.5-2 m 0-20 m Yes, depends on length
Connector LEMO BNC adaptor Yes, order separately
In situ gold pin connector* No Yes

*When mounted with in situ mini connectors, the shaft has no protection mounted, but fits directly into the in situ sensor mounts with pressure compensation. In situ sensors have a standard length of 130-160 mm.

Characteristics
Attribute Standard Options Extra price for option selection
Guaranteed lifetime 3 months
Expected lifetime > 6 months
Temperature range -2-60°C
Range About 0-1 mM H2S in water 0-50 mM 20%
Linear range About 0-300 µM H2S in water | About 0-100 µM for LR (Low Range) sensors 0-20 mM 20%
Detection limit 0.3 µM 30 nM for H2S-50LR | 20 nM for H2S-100/500/NP LR
Internal reference Yes
Internal guard Yes
Waterproof Yes
Spatial resolution Equals outside tip diameter
Signal drift 50% per month
Stirring Sensitivity & Response Time
Item Stirring sensitivity Response time (90%) Extra price
H2S <2% <10 s | H2S-500 <20 s 15%
Type 1: SULF
Type 2: H2S
Chemical Interferences
Chemical Interferences
Name Formula Interference for gases in gas phase (%) Interference for gases dissolved in water (%)
Methane CH4 0* 0**
Carbon dioxide CO2 0 0
Nitrogen N2 0 0
Oxygen O2 0 0
Air O2, N2, Ar 0 0
Nitrous oxide N2O 0 0
Ammonia NH3 0 0
Hydrogen H2 0.8 96
Carbon monoxide CO 0.6 77
Dimethyl sulfide (CH3)2S 18 18
Methyl mercaptan CH3SH 174 44
Ethyl mercaptan C2H6S 13 14
Sulfur dioxide SO2 40 1

*Given as signal for the interfering species in % of H₂S signal at equal partial pressures

**Given as signal for the interfering species in % of H₂S signal at equal molar concentrations

Chemical Interferences
Chemical Interferences
Name Formula Interference for gases in gas phase (%) Interference for gases dissolved in water (%)
Methane CH4 0* 0**
Carbon dioxide CO2 0 0
Nitrogen N2 0 0
Oxygen O2 0 0
Air O2, N2, Ar 0 0
Nitrous oxide N2O 0 0
Ammonia NH3 0 0
Hydrogen H2 0.03 4
Carbon monoxide CO 4 487
Dimethyl sulfide (CH3)2S 3 3
Methyl mercaptan CH3SH 117 30
Ethyl mercaptan C2H6S 8 9
Sulfur dioxide SO2 34 1

*Given as signal for the interfering species in % of H₂S signal at equal partial pressures

**Given as signal for the interfering species in % of H₂S signal at equal molar concentrations

Type 1: SULF
Type 2: H2S
Ordering information & Sizes
Ordering information & Sizes
Type 1: SULF Size and description Options Extra price for option selection
SULF-10 8-12 µm - glass sensor 3-5 µm 20%
SULF-25 20-30 µm - glass sensor
SULF-50 40-60 µm - glass sensor
SULF-100 90-110 µm - glass sensor
SULF-200 175-225 µm - glass sensor
SULF-500 400-600 µm - glass sensor
SULF-Eddy 40-60 µm - for Eddy Correlation System
SULF-50LR 40-60 µm - low range
SULF-100LR 90-110 µm - low range
SULF-500LR 400-600 µm - low range
SULF-MR 400-600 µm - in guide 100-400, 600-800 µm 20%
SULF-N 1.1 x 40 mm - needle sensor
SULF-NP 1.6 x 40 mm - needle sensor for piercing
SULF-NPLR 1.6 x 40 mm - needle sensor for piercing - low range
SULF-ST-1/4 1/4'' steel tube
SULF-SL-1/4 FT-cell 1/4'' Swagelok Tee
SULF-SL-1/8 FT-cell 1/8'' Swagelok Tee
SULF-PEEK-1/8 FT-cell 1/8'' PEEK Tee
SULF-PEEK-1/16 FT-cell 1/16'' PEEK Tee
SULF-FT-GLASS-6 Glass FT-cell 6mm outer diameter
SULF-FT-GLASS-8 Glass FT-cell 8mm outer diameter
Ordering information & Sizes
Ordering information & Sizes
Type 2: H2S Size and description Options Extra price for option selection
H2S-10 8-12 µm - glass sensor 3-5 µm 20%
H2S-25 20-30 µm - glass sensor
H2S-50 40-60 µm - glass sensor
H2S-100 90-110 µm - glass sensor
H2S-200 175-225 µm - glass sensor
H2S-500 400-600 µm - glass sensor
H2S-Eddy 40-60 µm - for Eddy Correlation System
H2S-50LR 40-60 µm - low range
H2S-100LR 90-110 µm - low range
H2S-500LR 400-600 µm - low range
H2S-MR 400-600 µm - in guide 100-400, 600-800 µm 20%
H2S-N 1.1 x 40 mm - needle sensor
H2S-NP 1.6 x 40 mm - needle sensor for piercing
H2S-NPLR 1.6 x 40 mm - needle sensor for piercing - low range
H2S-ST-1/4 1/4'' steel tube
H2S-SL-1/4 FT-cell 1/4'' Swagelok Tee
H2S-SL-1/8 FT-cell 1/8'' Swagelok Tee
H2S-PEEK-1/8 FT-cell 1/8'' PEEK Tee
H2S-PEEK-1/16 FT-cell 1/16'' PEEK Tee
H2S-FT-GLASS-6 Glass FT-cell 6mm outer diameter
H2S-FT-GLASS-8 Glass FT-cell 8mm outer diameter

Video Guides

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Quick Guide SULF Microsensors

We look into how SULF sensors are made, how they work, their specifications, and possible customizations.

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Quick Guide H2S Microsensors

Learn when to choose H2S over SULF, the applications as well as specifications and customizations.

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H2S Calibration Kit Video

Application Scientist Tage Dalsgaard shows you how to perform a 2-point calibration with H2S free water and one known H2S concentration

Related publications

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An Amperometric Microsensor for the Determination of H 2 S in Aquatic Environments
Jeroschewski, Paul et all (1996), Analytical Chemistry, vol. 68, 4351-4357
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