Analysis of Phthalates Using the Agilent 5977C GC/MSD with Hydrogen Carrier Gas

Significance of the Topic

Phthalates are widely used to modify plastic properties but are not covalently bound, leading to environmental release and human exposure. Regulatory limits on these plasticizers have increased demand for robust analytical methods capable of detecting trace levels in various matrices.

Study Objectives and Overview

This application note evaluates the performance of an Agilent 8890 gas chromatograph coupled to a 5977C Inert Plus GC/MSD using hydrogen as the carrier gas. The method targets 19 phthalates in selected ion monitoring mode to achieve high sensitivity, reliable calibration from low picogram levels, and significant reduction in analysis time compared to helium-based approaches.

Methodology and Instrumentation

• GC/MS System: Agilent 8890 GC with 7693A autosampler; 5977C Inert Plus GC/MSD with Inert Plus Extractor EI source and 9 mm lens.
• Carrier Gas: 99.9999 % purity hydrogen at constant flow (0.9 mL/min).
• Column: Agilent J&W HP-5ms UI, 20 m × 0.18 mm, 0.18 µm film.
• Injection: Pulsed splitless (25 psi for 0.9 min), 1 µL volume using Ultra Inert mid-frit liner at 280 °C.
• MS Conditions: SIM mode with quantifier and qualifier ions for each phthalate; transfer line at 280 °C; ion source at 300 °C; quadrupole at 150 °C.
• Sample Preparation: Calibration standards in isooctane over relevant ranges; vial inserts, septa, and pipettes were prebaked to minimise background.

Key Results and Discussion

Hydrogen carrier gas combined with a narrower column halved analysis time to approximately 14.5 minutes while maintaining excellent peak shape and resolution. Calibration performance:

• Linear quantification for 14 phthalates from 1 to 1 000 pg.
• Quadratic fits required for DMEP and DBEP; DEHP linear from 2.5 to 1 000 pg.
• DINP and DIDP (isomeric mixtures) quantified linearly from 50 to 20 000 pg.

Contamination issues from siloxanes and residual phthalates were addressed by using PTFE crimp or polyurethane snap caps, baking consumables at 130 °C, and cleaning the autosampler needle support. Instrument detection limits for individual phthalates ranged from approximately 0.16 to 0.73 pg, and about 7 pg for the isomeric mixtures.

Benefits and Practical Applications

• Reduced run time increases throughput in high-volume laboratories.
• Hydrogen carrier gas offers cost savings and mitigates helium supply issues.
• High sensitivity enables trace analysis in consumer products, packaging, and environmental samples.
• Optimised consumable selection ensures reproducible low-level quantification.

Future Trends and Opportunities

Growing interest in hydrogen as a sustainable and economical carrier gas is expected to drive further method standardisation and instrument adaptations. Advances in inert source materials and automation of cap and vial cleaning may simplify routine monitoring. Integration with large-scale screening workflows and non-targeted analysis could extend phthalate assessment to emerging compounds.

Conclusion

The Agilent 8890 GC coupled with the 5977C Inert Plus MSD and hydrogen carrier gas delivers robust, sensitive, and rapid analysis of a broad panel of phthalates. Careful management of consumables and system configuration enables calibration at low picogram levels, making this approach suitable for stringent QA/QC and regulatory testing.

References

• Bushey J. Phthalate Analysis Using an Agilent 8890 GC and 5977A GC/MSD. Agilent Technologies Application Note, 2018.
• Zhang J. Phthalates Analysis with Method GB 5009.271-2016 Using Agilent 8890 GC/MSD and JetClean. Agilent, 2019.
• Dao DL et al. Analysis of Phthalate with Hydrogen Carrier Gas. Agilent Technologies Application Note, 2024.
• Agilent EI GC/MS Instrument Helium to Hydrogen Carrier Gas Conversion Guide. Agilent, 2022.
• Andrianova AA; Quimby BD. Optimized GC/MS Analysis for PAHs. Agilent Technologies Application Note, 2019.
• Anderson KA et al. Self-Cleaning Ion Source for PAHs. J Chromatogr A, 2015.
• Quimby BD. In-Situ Conditioning in MS Systems. US Patent 8,378,293 B1, 2013.
• Agilent Inert Plus GC/MS System with HydroInert Source. Agilent Technologies, 2022.
• Quimby BD; Andrianova AA. MS Ion Source. US Patent 12,033,843 B2, 2024.