Determination of Phthalates in vegetables by GPC–GCMS

Significance of the Topic

Phthalates (PAEs) are prevalent plasticizers used to enhance the flexibility and durability of polymers in applications ranging from food packaging to agricultural films. Due to their endocrine-disrupting potential and widespread environmental occurrence, monitoring PAE residues in foodstuffs, particularly vegetables, is essential for consumer safety and regulatory compliance.

Objectives and Study Overview

The primary goal of this work was to establish a rapid, sensitive, and reproducible method for the simultaneous determination of 22 phthalate esters in vegetable matrices. The protocol integrates gel permeation chromatography (GPC) for sample cleanup with gas chromatography–mass spectrometry (GC–MS) detection in selected ion monitoring (SIM) mode.

Methodology and Instrumentation

• Sample Pretreatment: One gram of homogenized vegetable sample was extracted with water, followed by hexane partitioning and centrifugation to isolate PAE-containing organic phase.
• GPC Cleanup: Separation on Shodex CLNpak EV-200 column (2.1 mm × 150 mm) using acetone/cyclohexane (3:7, v/v) at 0.1 mL/min at 40 °C.
• GC–MS Analysis: WondaCap WAX capillary columns (5 m precolumn, 25 m analytical column) with temperature programming from 82 °C to 240 °C. The mass spectrometer operated in SIM mode targeting characteristic fragment ions for each phthalate.
• Instrument Platform: Shimadzu GPC–GCMS system.

Main Results and Discussion

Calibration curves for all 22 PAEs exhibited excellent linearity over 0.005–1.0 µg/mL (R² > 0.999). Repeatability tests at 0.05 µg/mL yielded relative standard deviations below 5%. Method detection limits, calculated at signal-to-noise ratio of 3, were under 3 µg/kg in vegetable samples. Spike-recovery experiments in lettuce, canola, and celery returned values between 60% and 130%, demonstrating acceptable accuracy across diverse matrices.

Benefits and Practical Applications

• The combined GPC–GCMS approach provides effective matrix cleanup and high selectivity through SIM detection.
• Low detection limits support compliance monitoring against regulatory thresholds.
• Streamlined sample preparation and rapid chromatographic runs facilitate high laboratory throughput.

Future Trends and Potential Applications

Advancements may include coupling GPC cleanup with high-resolution time-of-flight MS for non-target screening of emerging contaminants. Miniaturized and automated online GPC–GC workflows could enable near real-time surveillance of phthalate residues in food supply chains.

Conclusion

The developed GPC–GCMS method meets the requirements for reliable, sensitive, and efficient determination of multiple phthalates in vegetable samples. Its performance supports routine monitoring and ensures food safety.