Measuring sulphur compounds at trace levels (ppt): A real analytical challenge

Sulphur compounds are present in many industrial processes, particularly in the oil and gas sector, refineries, petrochemical plants and natural gas networks. Their monitoring is essential for process control, environmental compliance, odour management, health & safety. 

However, measuring sulphur compounds at trace levels (down to ppt range) remains a significant analytical challenge. At such low concentrations, measurements can be strongly affected by the sample matrix, humidity, adsorption phenomena, memory effects or concentration peaks. A GC must therefore combine high sensitivity with excellent selectivity, robustness and repeatability. CHROMATOTEC^® has developed two complementary systems dedicated to sulphur compounds monitoring: airmoMEDOR^® and airmoS. 

Sensitivity is part of the challenge

Detecting sulphur compounds at ppt levels requires a technology specifically designed for sulphur analysis. Industrial gas matrices can vary, making it essential to maintain reliable measurements despite changes in composition (matrix). At the same time, the analytical system must also protect the sample integrity and minimise adsorption of sulphur compounds on tubing and internal components.       

airmoMEDOR^®: robust sulphur monitoring for industrial applications

The airmoMEDOR^® is designed for the automatic measurement of sulphur compounds in ambient air at ppt levels. Its trapping technology provides high sensitivity while maintaining a linear response over a very wide concentration range.

A major advantage is its ability to cope efficiently with changes in matrix composition, making it particularly suitable for industrial applications. The analyser measures total mercaptans and total sulphur by sum, and its dual sampling principle (combining a sampling loop and a trap) extends the measurable concentration range within a single system.

An integrated permeation oven equipped with certified permeation tubes enables automatic calibration and validation. Its sulphur-specific detection provides accurate and repeatable results with high selectivity. The analyser can also directly calculate odour units, adding valuable information for odor monitoring applications.

With a detector lifetime exceeding 20 years, including the electrolyte, airmoMEDOR^® is designed as a low-maintenance solution requiring only operator-level expertise.

airmoS: advanced analysis for complex gas matrices

Designed for applications requiring more advanced analytical capabilities, airmoS combines thermal desorption gas chromatography with a double flame photometric detector (TD-GC-DFPD). The dual detector configuration helps avoid quenching effects and provides selective detection of sulphur compounds, including H₂S and CS₂, down to ppt levels.

airmoS can handle a wide variety of gas matrices, including natural gas, nitrogen, air, CO₂, methane and propane. Its flash thermal-desorption process ensures efficient purging between measurements, minimising memory effects.

Sample integrity is also critical at trace levels, specially treated tubing reduces adsorption of sulphur compounds, while humidity management limits unwanted reactions within the analytical system. The analyser is also designed to withstand high concentration peaks without detector damage.

From trace detection to reliable industrial monitoring

Both airmoMEDOR^® and airmoS integrate an internal permeation oven with certified permeation tubes, allowing automatic calibration and analytical validation. 

While airmoMEDOR^® focuses on robust, automated and low-maintenance monitoring, airmoS offers advanced chromatographic analysis for complex gas matrices and applications requiring experienced technical operation.