Analysis of Nonylphenols and Phthalates from Food Contact Packaging using GC/MS/MS

Significance of the Topic

Plastics and rubber products often contain alkylphenol ethoxylates that degrade into nonylphenols while phthalates and terephthalates can migrate from food-contact materials. These compounds pose environmental and health concerns due to their endocrine-disrupting properties. Sensitive and selective analytical methods are essential to monitor their presence in packaging and ensure consumer safety.

Objectives and Study Overview

This study aims to develop a robust GC/MS/MS protocol for simultaneous separation and trace-level quantification of nonylphenols and a broad range of phthalates and terephthalates in food packaging materials. Key goals include optimizing chromatographic conditions for isomer resolution and automating the MS/MS transitions for high-throughput analysis. The method was evaluated on various plastic films and containers.

Methodology and Sample Preparation

100 mg samples of common packaging types (plastic wrap, sandwich bag, polypropylene and polystyrene take-out containers) were extracted with 10 mL of hexane:ethyl acetate (4:1 v/v). Extractions were performed by sonication at 60 °C for 30 min. The solvent was evaporated under nitrogen and reconstituted in 1 mL fresh solvent, followed by centrifugation prior to analysis.

Instrumentation Used

• Gas chromatograph: Agilent 8890
• Triple quadrupole mass spectrometer: Agilent 7010C
• Column: DB-35ms UI, 20 m × 0.18 mm × 0.18 µm
• Inlet: Multimode inlet, cold pulsed splitless (50 °C to 280 °C)
• Carrier gas: Helium at 0.9 mL/min
• Transfer line temperature: 300 °C
• Quadrupole temp.: 150 °C; ion source: 280 °C
• Collision gases: He (4 mL/min), N₂ (1.5 mL/min)
• Data acquisition: dynamic MRM

Main Results and Discussion

Cold pulsed splitless injection with a UI fritted liner improved peak shape and reproducibility. Screening four phases (HP-5ms, VF-Xms, DB-17ms, DB-35ms) identified DB-35ms as the optimal stationary phase, achieving baseline separation of phthalate isomers and nonylphenol ethoxylate homologs. MS/MS optimization using MRM Optimizer enabled automated selection of precursor/product ions and collision energies. Detection limits reached 1 fg/µL for most compounds. In real samples, diethyl terephthalate, di-isobutyl phthalate and dibutyl phthalate were detected consistently, while nonylphenols appeared only in film and bag extracts.

Practical Benefits and Applications

• Sub-femtogram sensitivity for regulatory compliance testing.
• Chromatographic resolution of structural isomers ensures accurate quantitation.
• Automated MRM setup reduces method development time.
• Applicable to quality control of food-contact materials and environmental monitoring.

Future Trends and Applications

Emerging directions include expanding the analyte scope to novel plasticizers, integrating high-resolution MS for non-target screening, and developing fully automated workflows for large-scale monitoring. Coupling with green extraction techniques and miniaturized GC platforms may further enhance throughput and sustainability.

Conclusion

The optimized GC/TQ method with a DB-35ms column and cold pulsed splitless inlet, combined with automated MRM optimization, offers reliable isomer separation and trace-level detection of nonylphenols and phthalates in food packaging. This approach supports stringent quality control and safeguards consumer health.

Reference

• Votavová L, Dobiáš J, Voldřich M, Čížková H. Migration of nonylphenols from polymer packaging materials into food simulants. Czech Journal of Food Sciences. 2009;27:293-299.