Method
Gas chromatograph:
Kristall 2000M or Chromatec-Crystal 5000/9000
Detector type:
FPD (flame photometric detector)
Capillary columns used:
BP-5 column, 50 m × 0.53 mm × 5.0 µm
GS-GasPro column, 30 m × 0.32 mm, Cat. No. 113-4332
RTX-U-Bond column, 30 m × 0.53 mm × 20 µm
Injection system:
Thermostated 6-port or 10-port valves (automatic or manual, Valco or Chromatec valves)
Chromatographic data processing software:
Chromatec Gas
Additional equipment:
Hydrogen generator
Air compressor
Gas fittings kit 4.078.000
Catalytic air purification filter for removal of organic impurities
Electronic gas flow indicator 5.183.004
Certified gas mixtures of the target sulfur-containing components
Method Description
GOST R 53367-2009 allows the analysis of sulfur-containing compounds in natural combustible gases, including:
hydrogen sulfide, C1-C4 mercaptans, and carbonyl sulfide.
The standard can be used for the analysis of sulfur-containing compounds in methane, fuel gas, and natural gas simulants.
Measurement Range According to GOST R 53367-2009
| Component | Formula | Range, mg/m³ |
|---|---|---|
| Hydrogen sulfide | H2S | 1.0–50 |
| Methyl mercaptan | CH3SH | 1.0–50 |
| Ethyl mercaptan | C2H5SH | 1.0–50 |
| Propyl mercaptan | C3H7SH | 1.0–50 |
| Isopropyl mercaptan | C3H7SH | 1.0–50 |
| sec-Butyl mercaptan | C4H9SH | 1.0–50 |
| tert-Butyl mercaptan | C4H9SH | 1.0–50 |
| Isobutyl mercaptan | C4H9SH | 1.0–50 |
| Butyl mercaptan | C4H9SH | 1.0–50 |
| Carbonyl sulfide | COS | 1.0–50 |
Detector Features and Analytical Notes
The flame photometric detector (FPD) is the most widely used detector for the analysis of sulfur-containing compounds in natural gas. It offers high sensitivity, good selectivity, and low cost.
At the same time, it should be noted that the FPD has a signal quenching effect, which means that the resolution between sulfur-containing compounds and hydrocarbons must be at least 1.
To evaluate the degree of separation between sulfur-containing components and hydrocarbons in natural gas, the gas should be analyzed under conditions where the selectivity of the FPD is reduced, so that hydrocarbon peaks become visible on the chromatogram.
In addition, the detector is non-linear, therefore calibration is performed by constructing a calibration graph according to the function:
lg(y) = K1 × lg(x) + K0
where:
y = amount of substance
x = detector response (peak area)
According to GOST R 53367, chromatograph calibration is carried out for two working ranges — from 1 to 20 mg/m³ and from 20 to 50 mg/m³ — using two-point calibration with cylinders containing different concentrations of sulfur-containing compounds.
Recommended Configurations
For the analysis of mercaptan sulfur, it is sufficient to perform the analysis on one channel using a CR-5 column, 50 m × 0.53 mm × 5.0 µm.
If carbonyl sulfide (COS) analysis and determination of the total sulfur parameter are required, the analysis should be performed on two columns:
- CR-5, 50 m × 0.53 mm × 5.0 µm
- GS-GasPro, 30 m × 0.32 mm
On non-polar columns based on 100% dimethylpolysiloxane (CR-1, BP-1, HP-1, CP Sil 5CB, etc.) or 5% phenyl / 95% dimethylpolysiloxane (CR-5, BP-5, HP-5, CP Sil 8CB, etc.), carbonyl sulfide is not separated from propane in a single operating mode. For this reason, a second channel with a GasPro 30 m × 0.32 mm column is required.
In terms of separation efficiency for implementation of GOST R 53367, CR-5 columns, 50 m × 0.53 mm × 5.0 µm, perform better than DB-1, 60 m × 0.53 mm × 1.5 µm. That is why Chromatec recommends this solution for the application.
Alternative Detector Options
In addition to the FPD, Chromatec can also offer solutions based on PFPD (pulsed flame photometric detector) or a chemiluminescence detector.
However, for operation within the specified concentration ranges, these solutions are generally not economically justified due to the high cost of the detectors.