Together, the Agilent 5977/7890B Series GC/MSD and Markes TD systems allow you to take consistent air samples and confidently test them for a variety of contaminants.

Importance of the topic

Monitoring volatile and semi-volatile organic compounds in air is critical for protecting human health, ensuring regulatory compliance, and guiding environmental policy. Hazardous Air Pollutants (HAPs), ozone precursors, greenhouse gases, indoor pollutants, and landfill emissions all pose risks that demand accurate, sensitive, and versatile analytical methods. By integrating advanced thermal desorption (TD) and gas chromatography/mass spectrometry (GC/MS) systems, laboratories can address a wide range of compounds at trace levels across diverse sampling scenarios.

Objectives and Overview

The text presents a framework for reliable air quality testing using Agilent 5977/7890B GC/MSD coupled with Markes TD systems. It reviews US EPA Methods TO-14, TO-15, and TO-17 for ambient air toxics, urban ozone precursors, and indoor VOC profiling. The document also covers landfill gas analysis under evolving climate regulations and compares tube-based and canister sampling approaches.

Methodology and Used Instrumentation

The workflow relies on pumped or passive sampling onto multi-sorbent tubes and canisters:

• Thermal desorption: Desorb tubes at 280 °C for 5 min, split 15:1 during release, trap temperatures adjusted to sorbent type (25–300 °C).
• GC/MS analysis: Agilent 7890B GC with inert flow path, J&W Ultra Inert columns, backflush capability; 5977A MSD operated in scan mode.
• Sampling media: Multi-sorbent tubes for non-polar and polar organics; stainless steel canisters for ultra-volatiles (C2 hydrocarbons, freons) via EPA TO-15.

Instrument details:

• Thermal Desorption: Markes CIA Advantage or UNITY Series 2 TD (or TD-100).
• Gas Chromatograph: Agilent 7890B with Ultra Inert inlet liners, weldments, and ferrules.
• Mass Spectrometer: Agilent 5977A MSD with inert source.

Main Results and Discussion

Representative chromatograms demonstrate baseline separation and sharp peak shapes across 60+ target analytes, including C2–C10 hydrocarbons, chlorinated solvents, ketones, and aromatic compounds.

• EPA TO-17 profiling of urban air captured HAPs such as benzene, toluene, xylene isomers, and trichlorofluoromethane with ng/m³ sensitivity.
• TO-15 canister sampling effectively quantified ultra-volatile gases (e.g., CF4, C2F6) that are challenging on sorbent tubes.
• Indoor air TO-17 analysis detected ppt–ppb VOCs from building materials, furnishing, and soils.
• Landfill gas profiling identified odorous sulfur compounds and toxic chlorinated species down to trace levels.

Inert flow path innovations minimized analyte loss and improved quantitative accuracy. Backflush technology extended column lifetime for heavy-matrix samples.

Benefits and Practical Applications

Employing combined TD-GC/MS approaches provides:

• High versatility: One system covers polar, non-polar, volatile, and semi-volatile compounds.
• Regulatory compliance: Meets EPA Methods TO-14, TO-15, TO-17, EN ISO 16017-1, ASTM D6196.
• Enhanced sensitivity and reproducibility through inert flow path hardware.
• Operational flexibility: Active/passive sampling, canister or tube media for tailored applications.

Future Trends and Potential Applications

Anticipated developments include:

• Online real-time monitoring platforms integrating TD-GC/MS with remote sampling probes.
• Expanded compound libraries to address emerging contaminants and greenhouse gases.
• Miniaturized TD units for field deployment and automated sampling networks.
• Coupling with high-resolution MS or tandem MS for improved selectivity in complex matrices.

Conclusion

The synergy of Agilent GC/MSD instruments and Markes thermal desorption systems offers a comprehensive solution for trace-level analysis of organic vapors in ambient, indoor, and landfill air. By adhering to established EPA and international methods, laboratories gain confidence in data quality, regulatory compliance, and environmental decision-making.