Determination of Phthalate Compounds in Plastic Toys Using the Varian 225-MS Ion Trap Mass Spectrometer

Significance of the topic

Phthalate esters are widely used as plasticizers in PVC toy materials but have been linked to endocrine disruption and developmental effects in children. Regulatory bodies in the EU and the US have set strict limits on six phthalates in childcare products, driving the need for sensitive, reliable analytical methods to ensure compliance and protect consumer safety.

Objectives and study overview

This application note describes the quantitative determination of six regulated phthalates in plastic toy extracts using the Varian 225-MS ion trap mass spectrometer coupled to a 431-GC gas chromatograph. The method follows the framework of the US Consumer Product Safety Commission (CPSC) GC/MS procedure and explores the advantages of low-pressure chemical ionization (CI) and MS/MS for direct screening of polymer samples.

Methodology and instrumentation

Toy extract samples were provided by the California Department of Toxic Substances Control and prepared by Soxhlet extraction in dichloromethane (16 h at 60 °C). Calibration standards (0.25–10 µg/mL) were prepared in cyclohexane with benzyl benzoate as an internal standard (1 µg/mL). GC separation was achieved on a 30 m × 0.25 mm VF-5ms capillary column with helium carrier gas (1 mL/min) in splitless pulsed injection mode. MS analysis employed electron impact (EI) full-scan mode and low-pressure CI with methyl t-butyl ether (MTBE) reagent, enabling detection of characteristic molecular ions and MS/MS confirmation.

Main results and discussion

EI spectra of all target phthalates exhibit a dominant fragment ion at m/z 149 (m/z 163 for dimethyl phthalate). Total ion and extracted ion chromatograms demonstrate partial co-elution of di-n-octyl (DnOP), diisononyl (DINP), and diisodecyl (DIDP) phthalates; quantitation ions at m/z 279, 293, and 307 yield calibration coefficients ≥ 0.998 and reproducibility better than 5 % RSD. CI/MS/MS produces abundant protonated molecules (e.g., m/z 419 for DINP, m/z 447 for DIDP) and simplifies spectra, facilitating unambiguous identification in complex PVC extracts. Direct thermal desorption of plastic via the ChromatoProbe device, combined with CI/MS/MS, allows screening of solid samples without prior cleanup.

Benefits and practical applications

• High sensitivity and specificity through EI full scan and CI/MS/MS confirmatory scans.
• Excellent linearity and precision across regulatory concentration ranges.
• Minimal sample preparation using ChromatoProbe for direct analysis of polymer fragments.
• Compliance with CPSC and EU testing requirements for routine QA/QC in toy safety laboratories.

Future trends and potential applications

Emerging low-pressure CI techniques and advanced ion trap MS/MS workflows are expected to expand rapid screening capabilities for a broader range of plastic additives and emerging contaminants. Integration with automated sampling platforms and coupling to high-resolution MS detectors will further enhance throughput and structural elucidation in industrial safety and environmental monitoring.

Conclusion

The Varian 225-MS ion trap system combined with GC/EI and low-pressure CI/MS/MS provides a robust, accurate, and streamlined approach for quantifying regulated phthalates in plastic toys. The method meets regulatory requirements and offers the added benefit of direct solid sampling, improving laboratory efficiency and confidence in complex matrices.

Reference

• Official Journal of the European Communities Decision 199/815/EC, 1999.
• U.S. Consumer Product Safety Improvement Act (CPSIA 2008).
• U.S. Consumer Product Safety Commission GC/MS test method.
• European Commission Joint Research Centre, CRL-FCM database.