Rapid analysis of polychlorinated biphenyls (PCBs) in vegetables by QuEChERS-based extraction and GPC–GCMS

Significance of the Topic

Polychlorinated biphenyls (PCBs) are persistent organic pollutants with carcinogenic, teratogenic and mutagenic properties. Although banned decades ago, they continue to accumulate in air, soil, water and food chains worldwide. Rapid, reliable detection of trace-level PCBs in vegetables is essential for ensuring food safety and protecting public health.

Objectives and Study Overview

This study presents a streamlined workflow to extract and quantify seven indicator PCBs in carrot and ginger matrices. By coupling a QuEChERS-based sample preparation with gel permeation chromatography–gas chromatography–mass spectrometry (GPC–GC/MS), the method aims to efficiently remove macromolecular interferences such as oils and pigments, while delivering high sensitivity and throughput suitable for routine quality control.

Methodology

• Sample Preparation: 10 g of homogenized vegetable was vortex-extracted with 10 mL acetonitrile, in the presence of MgSO₄ and NaCl, followed by dispersive solid-phase extraction using PSA and MgSO₄.
• Gel Permeation Chromatography (GPC): Separation on Shodex CLNpak EV-200 column (2.1 mm × 150 mm) with acetone/cyclohexane (3:7 v/v) at 0.1 mL/min; 10 µL injection volume.

Used Instrumentation

• GPC System: Shimadzu GPC module paired with Shodex CLNpak EV-200 column.
• GC–MS System: Shimadzu GC–MS with Rtx-5 MS pre-column (5 m × 0.25 mm × 0.25 µm) and analytical column (25 m × 0.25 mm × 0.25 µm); selected ion monitoring (SIM); programmable temperature vaporization (PTV) injection and optimized temperature and pressure programs.

Main Results and Discussion

The method showed excellent linearity for all seven PCBs (R² > 0.998) across 1–500 µg/L. Limits of detection were below 0.05 µg/L for most congeners. Precision tests (n=6 at 1 µg/L) yielded relative standard deviations below 5%. Spiked recoveries ranged from 97% to 126% in carrot and 85% to 104% in ginger. Analysis of commercial samples detected no PCB residues above the method detection limits.

Benefits and Practical Applications

• High sensitivity and precision enable reliable trace-level measurements.
• QuEChERS extraction combined with online GPC cleanup simplifies sample handling and effectively removes matrix interferences.
• Rapid throughput supports routine monitoring and quality control of vegetables in food safety laboratories.

Future Trends and Opportunities

• Extension of the approach to a wider range of produce and environmental matrices.
• Automation and miniaturization of sample preparation to increase throughput and reduce solvent use.
• Integration with high-resolution mass spectrometry for improved selectivity and quantitation of emerging contaminants.
• Adoption of greener solvents and sustainable practices to minimize environmental impact.

Conclusion

The combined QuEChERS extraction and GPC–GC/MS method offers a robust, efficient and sensitive platform for routine analysis of PCBs in vegetables. Its strong performance characteristics and simplified workflow make it ideal for food safety monitoring and regulatory compliance.