Method
Gas chromatograph:
Chromatec-Crystal 9000
Detector type:
SCD Chemiluminescence Detector
Examples of capillary columns used:
DB-Sulfur SCD column, 60 m × 0.32 mm × 4.2 µm, #G3903-63001
Select Low Sulfur column, 60 m × 0.32 mm, #CP8575
CP-Sil 5 CB for sulfur column, 30 m × 0.32 mm × 4 µm, Cat. No. CP7529
Injection system:
6-port valve, thermostated, inert to sulfur-containing compounds
Additional equipment:
Hydrogen generator (high-purity models should be used)
Gas fittings kit 4.078.000
Electronic gas flow indicator 214.5.183.004 or built-in gas flow indicator
Certified gas mixtures of the target sulfur-containing compounds
Leak detector
Method Description
The ASTM D5504 method provides the highest sensitivity among chromatographic methods for the analysis of sulfur-containing compounds.
The working range is 0.01–1000 mg/m³.
This range can be extended by using a sample loop of a different volume; the specified range applies to a 1 mL loop.
Such high sensitivity is achieved through the use of the SCD detector.
Chromatec-Crystal 9000 chromatograph with SCD detector and DAZh-2M injector
The SCD Chemiluminescence Detector provides high sensitivity, stable operation, and no hydrocarbon flame-quenching effect, and is suitable for different types of hydrocarbons.
Its equimolar response makes it possible to determine the total sulfur content while simultaneously enabling qualitative identification of sulfur compounds and their classes.
Operating Principle of the SCD Chemiluminescence Detector
The substances separated on the chromatographic column enter the plasma furnace, where sulfur compounds are combusted to SO₂.
Sulfur dioxide is then reduced in the presence of an excess amount of hydrogen to various sulfur compounds with low oxidation states.
These compounds are subsequently transferred into the reaction chamber.
At the same time, ozone generated in the ozonizer also enters the reaction chamber. It reacts with these reduced sulfur compounds, producing sulfur dioxide in an excited state.
When the excited sulfur dioxide returns to its ground state, a photon is emitted.
The emitted light is measured by a photomultiplier tube and converted into an electrical signal.
Additional Notes
In many cases, the chromatograph is configured not only for the analysis of gaseous samples, but also for liquid samples and liquefied gas.
Standard
ASTM D5504
Standard Test Method for Determination of Sulfur Compounds in Natural Gas and Gaseous Fuels by Gas Chromatography and Chemiluminescence.