Agilent 355 Sulfur Chemiluminescence Detector (355 SCD): Sulfur Compounds in Ethylene and Propylene

Importance of the Topic

The detection of trace volatile sulfur compounds in olefin feedstocks is critical for process optimization, product quality, and environmental compliance.
These sulfur species, even at low concentrations, can poison catalysts, impair polymer properties, and generate harmful emissions.

Study Goals and Overview

This technical overview evaluates the performance of the Agilent 355 Sulfur Chemiluminescence Detector (SCD) coupled to gas chromatography for analysis of hydrogen sulfide (H₂S), carbonyl sulfide (COS), and other volatile sulfur compounds in ethylene and propylene matrices.
The objectives include demonstration of selectivity, sensitivity, and resistance to hydrocarbon matrix interference.

Methodology and Instrumentation

A 5890 Series II gas chromatograph equipped with a split/splitless injector was used.
The injector operated at a 1:6 split ratio with a carrier gas linear velocity of ~38 cm/s.
Column options include a 15 m Astec GasPro capillary (0.32 mm id) or a 30 m CP-SilicaPLOT (0.32 mm id) for ambient separation of light sulfur species.
Temperature programs varied by analysis:

• COS in propylene: 50 °C hold 1 min, ramp to 100 °C at 10 °C/min.
• H₂S in ethylene: 40 °C hold 1 min, ramp to 100 °C at 10 °C/min.

The Agilent 355 SCD was connected directly to the column outlet and operated under standard chemiluminescence conditions.

Key Results and Discussion

Chromatograms demonstrate the SCD’s exclusive response to sulfur species with no detectable baseline disturbance or quenching by the hydrocarbon matrix.
The analysis of 60 ppb COS in propylene yielded a sharp, interference-free peak.
Similarly, 100 ppb H₂S in ethylene coeluted with ethylene but still produced a clear, unquenched sulfur signal despite band broadening.

Benefits and Practical Applications

The SCD’s high sulfur selectivity and sensitivity enable accurate determination of individual sulfur compounds and total sulfur content in olefin streams.
Its robustness against hydrocarbon interference simplifies sample introduction and reduces the need for extensive sample cleanup.
Applications include fugitive emission monitoring, feedstock quality control, and catalyst life assessment.

Future Trends and Opportunities

Advances in capillary column chemistries will further improve ambient separation of light sulfur species, enabling faster cycle times and lower detection limits.
Integration with automated sample handling and real-time data processing will support on-line monitoring in petrochemical and polymer plants.
Emerging portable GC-SCD systems may extend routine sulfur analysis to field environments.

Conclusion

The Agilent 355 SCD combined with optimized capillary columns provides a powerful, interference-free solution for trace sulfur analysis in ethylene and propylene.
This approach delivers reliable, selective detection of H₂S, COS, and related compounds, supporting quality control and environmental objectives in petrochemical operations.

Reference

• Agilent Technologies. Agilent 355 Sulfur Chemiluminescence Detector (355 SCD): Sulfur Compounds in Ethylene and Propylene. Technical Overview, 2007.