SBSE-GC-TOFMS Analysis Showing Deconvolution of Heptachlor Epoxide in Brewed Green Tea

Significance of the Topic

Point-of-need detection of trace-level pesticides in beverages is critical for consumer safety and regulatory compliance. Heptachlor epoxide is a persistent organochlorine pesticide; monitoring its presence in tea infusions requires highly sensitive analytical techniques.

Aims and Study Overview

The primary aim was to demonstrate how stir bar sorptive extraction coupled with gas chromatography time-of-flight mass spectrometry (SBSE-GC-TOFMS) can detect and deconvolute heptachlor epoxide at low concentration levels in brewed green tea. This application snapshot highlights method performance at picogram-per-millilitre levels.

Methodology and Instrumentation Used

• Sample preparation: Stir bar sorptive extraction (SBSE) of the brewed green tea matrix.
• Chromatographic separation: 20 m × 0.18 mm × 0.18 µm Rxi-5ms capillary column.
• Detection: LECO Pegasus GC-TOFMS, scan range 45–450 m/z at 5 spectra per second.
• Quantitation: Target mass m/z 335 for heptachlor epoxide.

Main Results and Discussion

The total ion chromatogram revealed a distinct peak at approximately 408 s corresponding to heptachlor epoxide. Deconvolution of overlapping signals enabled reliable identification at a concentration of 100 ppt. A 3-second zoom window around this retention time confirmed accurate peak shape and quantitation.

Benefits and Practical Applications

• Enables trace-level detection of persistent pesticides in tea beverages.
• Enhanced selectivity through spectral deconvolution minimizes matrix interferences.
• Suitable for routine safety monitoring and compliance testing in food and beverage industries.

Future Trends and Applications

Advances may include automated SBSE workflows, novel sorptive coatings for broader analyte coverage, and coupling with high-resolution mass spectrometry for improved selectivity. This approach can be extended to various food, environmental, and biological matrices.

Conclusion

SBSE-GC-TOFMS demonstrates a robust capability for detecting and accurately quantifying heptachlor epoxide in complex matrices such as brewed green tea at ppt levels, offering a valuable tool for regulatory laboratories and quality assurance programs.

Reference

• LECO Corporation. SBSE-GC-TOFMS Analysis Showing Deconvolution of Heptachlor Epoxide in Brewed Green Tea. Application Snapshot. Form No. 209-200-080, September 2008.