EPA and EU Phthalates on Rtx®-440

Significance of the topic

Phthalate esters are widely used plasticizers that can leach into environmental and consumer products, posing health and regulatory concerns. Sensitive and rapid analytical methods are essential for monitoring these compounds to ensure compliance with EPA and EU guidelines.

Objectives and study overview

The primary aim of this study was to evaluate the separation efficiency and speed of a Restek Rtx-440 column for twenty EPA- and EU-regulated phthalate esters under conditions aligned with EPA Method 8061A. The focus was on achieving baseline resolution in a runtime compatible with high-throughput laboratory demands.

Used Instrumentation

• Gas chromatograph: Shimadzu 2010 GC
• Mass spectrometer: Shimadzu QP2010+ quadrupole MS
• Column: Rtx®-440, 30 m × 0.25 mm ID, 0.25 µm film thickness
• Ionization mode: Electron impact at 70 eV
• Transfer line temperature: 300 °C; Source temperature: 280 °C
• Carrier gas: Helium at constant linear velocity (66.7 cm/s ≈ 3 mL/min at 200 °C)

Methodology

A standard mixture of twenty phthalate esters (50 µg/mL; 80 µg/mL benzyl benzoate as internal standard) was prepared in methylene chloride. A 1 µL split injection (20:1) was performed at 280 °C. The oven program ramped from 200 °C (0.5 min) to 330 °C at 30 °C/min (hold 1 min), yielding a total analysis time of 5.25 min. Full-scan MS data were acquired from m/z 59–400 with a 0.1 s scan interval, monitoring target ions at m/z 293 and 307.

Main results and discussion

All twenty phthalate esters were baseline separated within 5.25 min, demonstrating the selectivity of the Rtx-440 phase for both low- and high-boiling compounds. Sharp, symmetric peaks and consistent retention times were observed. Extracted ion chromatograms confirmed resolution of critical pairs, such as di-n-pentyl and bis(2-methoxyethyl) phthalate, under the rapid temperature program.

Benefits and practical applications

• High throughput screening of regulated phthalates in environmental, food, and consumer matrices
• Regulatory compliance with EPA Method 8061A and corresponding EU standards
• Reduced solvent use and energy consumption due to short analysis time
• Robust performance with minimal maintenance demands and high reproducibility

Future trends and opportunities

Integration of Rtx-440 with high-resolution or fast-scanning mass spectrometers could enable non-target screening of emerging plasticizers. Sample introduction via solid-phase microextraction or thermal desorption may reduce sample prep time. Adoption of micro-bore columns and ultra-fast temperature programs could further shorten runtimes below 3 min while retaining separation efficiency.

Conclusion

The Restek Rtx-440 column provides rapid, reliable baseline separation of twenty phthalate esters under EPA Method 8061A conditions. Its high selectivity, short analysis time, and robust performance make it an excellent choice for routine QA/QC and environmental monitoring laboratories aiming for high throughput without compromising data quality.

Reference

• EPA Method 8061A: Phthalate Esters by Gas Chromatography/Mass Spectrometry
• Restek Rtx-440 Column Technical Guide, Restek Corporation
• Shimadzu QP2010+ GC-MS Operation Manual, Shimadzu Corporation