Analysis of Pesticides in Brewed Green Tea by SBSE-GCxGC-TOFMS Showing Baseline Resolution of Three Pesticides in the 2 Dimension Separation

Importance of the Topic

The presence of trace pesticides in brewed green tea poses risks to consumer health and necessitates highly sensitive and selective analytical approaches to ensure food safety and regulatory compliance. The combination of stir bar sorptive extraction with comprehensive two-dimensional gas chromatography and time-of-flight mass spectrometry (SBSE-GCxGC-TOFMS) addresses these challenges by offering enhanced trace-level detection in complex matrices.

Study Objectives and Overview

This application snapshot illustrates the baseline resolution of three organophosphorus and organochlorine pesticides—disulfoton, γ-lindane, and diazinone—spiked at 250 parts per trillion into brewed green tea. The goal is to demonstrate the efficacy of SBSE-GCxGC-TOFMS for separating and quantifying coeluting analytes.

Methodology

Samples were prepared by spiking brewed green tea with the target pesticides at 250 ppt. Analytes were extracted using stir bar sorptive extraction and separated via comprehensive two-dimensional gas chromatography. Mass spectral data were acquired over an m/z range of 45–550 at 150 spectra per second.

Used Instrumentation

• Stir Bar Sorptive Extraction coupled to GC×GC
• Primary Column: 10 m × 0.18 mm × 0.2 μm Rtx-5
• Secondary Column: 1.5 m × 0.10 mm × 0.10 μm DB-17
• Time-of-Flight Mass Spectrometer (45–550 m/z, 150 spectra/s)
• Instrumentation Platform: JH-Pegasus 4D SBSE-GC×GC-TOFMS

Main Results and Discussion

In the reconstructed one-dimensional chromatogram, the three pesticides exhibit complete coelution, as evidenced by unique ions m/z 137, 88, and 111. The two-dimensional contour plot confirms baseline resolution in the second dimension, highlighting the increased peak capacity and selectivity of the GC×GC separation.

Benefits and Practical Applications

• Sub-part-per-billion detection limits in complex beverages
• Improved separation of coeluting compounds for accurate quantification
• High-throughput screening suitable for food safety and environmental monitoring

Future Trends and Applications

Advancements may include coupling SBSE-GC×GC with high-resolution mass analyzers and automation for broader screening of pesticide residues. The methodology shows promise for adoption in regulatory laboratories and industrial QA/QC settings.

Conclusion

SBSE-GC×GC-TOFMS provides a robust approach for trace-level pesticide analysis in brewed green tea, achieving baseline resolution of challenging analytes and offering a powerful tool for ensuring consumer safety.

Reference

• LECO Corporation. Form No. 209-200-132. JH-Pegasus 4D SBSE-GC×GC-TOFMS Baseline Resolution. October 2008.