Rapid determination of phthalates in polymers

Importance of the Topic

Phthalates are widely used plasticizers in polymers with known health risks including endocrine disruption and reproductive toxicity. Regulatory limits require rapid and reliable screening methods for these compounds in industrial and consumer products.

Objectives and Study Overview

The aim was to develop a simple, highly automated Pyrolysis/Thermal Desorption GC-MS method for quantifying phthalates in polymers. The method follows IEC 62321-8:2017 guidelines and seeks to reduce analysis time, solvent use, and sample size while ensuring regulatory compliance.

Methodology and Instrumentation

Sample Preparation:

• Weigh approximately 0.50 mg of polymer sample into a pyrolyzer cup with glass wool support
• Accurate to 0.01 mg for trace analysis

Instrument Configuration:

• Front end: Frontier EGA/PY-3030D multi-shot pyrolyzer with thermal desorption accessory
• GC: Thermo Scientific TRACE 1310 equipped with TraceGOLD TG-5HT column (15 m × 0.25 mm × 0.10 μm)
• MS: Thermo Scientific ISQ 7000 single quadrupole MS, EI mode at 70 eV, SIM acquisition
• Data System: Chromeleon CDS v7.2 with e-Workflow for acquisition, processing, and reporting

Key Parameters:

• Carrier gas: Helium at 1.5 mL/min constant flow
• Injector: Split mode, 300 °C, split ratio 100:1
• Oven program: 80 °C hold, ramp 50 °C/min to 300 °C, total run time 10.0 min including pyrolysis
• Pyrolysis: Initial 200 °C, ramp 50 °C/min to 340 °C, hold 1 min

Main Results and Discussion

Chromatographic Performance:

• Baseline resolution and symmetric peaks for four phthalates (DIBP, DBP, BBP, DEHP)
• Retention times from 2.61 to 3.81 min
• RSD values 5.7–7.9% over eight separate analyses of a 1000 mg/kg PVC standard
• Negligible system residue after nine consecutive injections

Sample Analysis:
Three different polymer samples showed variable phthalate levels (mg/kg) in line with expected contamination patterns. The method identified DIBP, DBP, BBP, and DEHP with clear SIM signals.
Comparison with Soxhlet:

• Pyrolyzer method eliminates solvent use (saving 170 mL n-hexane per sample)
• Reduces sample amount by 1000×
• Analysis time per sample under 10 min versus over 6 hours for Soxhlet extraction
• Five times higher throughput for a batch of 10 samples

Benefits and Practical Applications

The developed Py/TD-GC-MS approach offers:

• High automation and ease of use with up to 48 sample capacity
• Reduced health and safety concerns by eliminating organic solvents
• Cost savings in sample preparation and waste disposal
• Compliance with international standards for phthalate analysis

Future Trends and Potential Applications

Advances may include:

• Extension to other plastic additives and contaminants
• Integration with high-resolution mass spectrometry for non-target screening
• Miniaturized pyrolyzer interfaces for onsite testing
• AI-driven data analysis for faster decision making

Conclusion

The Pyrolyzer/Thermal Desorption GC-MS method provides a rapid, solvent-free, and reliable solution for phthalate determination in polymers. It enables significant time savings, high throughput, and regulatory compliance in industrial and quality control laboratories.

Used Instrumentation

• Frontier EGA/PY-3030D multi-shot Pyrolyzer with thermal desorption accessory
• Thermo Scientific TRACE 1310 Gas Chromatograph with TraceGOLD TG-5HT column
• Thermo Scientific ISQ 7000 single quadrupole mass spectrometer
• Chromeleon Chromatography Data System v7.2

References

1. Benjamin S; Masai E; Kamimura N; Takahashi K; Anderson RC; Faisal PA. Phthalates impact human health Epidemiological evidences and plausible mechanism of action Journal of Hazardous Materials 2017 340 360-383
2. International Electrotechnical Commission IEC 62321-8 2017 Determination of certain substances in electrotechnical products – Part 8 Phthalates in polymers by gas chromatography-mass spectrometry using a pyrolyzer/thermal desorption accessory