H2S in Natural Gas

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H2S in natural gas is usually tested by Tutweiler or Kitagawa detection tubes.

my question is, why can it not be tested by GC/TCD?

During the analysis of natural gas, i find the area counter of H2S has a correlation with the concentration of H2S.

[shabhari]

Hello Friend,
you can detect H2S with TCD detector. We are measuring H2S in natural gas by this method.

[adi]

Hello Friend,
you can detect H2S with TCD detector. We are measuring H2S in natural gas by this method.

Hi,

You can use TCD for H2S detection in Natural Gas. Some notes:
1. Lower Detection limit for TCD is 0.5% if you use packed column for separation(with some special requirement, see no 2). If you used capillary column, 100 ppm is possible to be detected.
2. If your GC configuration is for GPA 2261(3 valves, 4 packed columns), is almost impossible to detect H2S since the H2S reacted with the stainless steel material of the system. You must used a special treated column (Sulfinert or silcosteel), special valve body (hastelloy C or other), special sample loop (Sulfinert or silcosteel) to prevent lost of the H2S before eluting to detector.
3. You can use single capillary column (GS-Gas pro), sulfinert or silcosteel sample loop and Volatile Interface Inlet to get a good recovery of your H2S. If H2S is lower than 100 ppm, then you can use PFPD or FPD as a detection device. But if it more than 100 ppm, TCD is sufficient enough.

No 3 is applicable if you don't need to measure the other Natural Gas content (Hydrocarbon, CO2 and N2). It's just for sulfur detection.
hope this help.
Adi

[chromatographer1]

The lowest reproducible levels of H2S detected by a TCD that I have seen on a GC system is about 4 ppm. Special but available deactivated materials as ADI mentioned are required. Since it appears your chromatography system is adequate to detect H2S your equipment may be adequate. Remember though if your system is just deactivated by previous long term contact with H2S if you replace columns or other parts of your system that have never had H2S contact they may remove H2S from your sample before your detector sees it.

A Helium Ionization detector should also be very sensitive to H2S if the other detectors mentioned are not available to you.