Determination of Phthalate Esters in Soft Drinks By GC-MS

Importance of the topic

Phthalate esters are widely used plasticizers in PVC and have been identified as endocrine disruptors. Their presence in soft drinks raises health concerns, prompting the need for sensitive and reliable analytical methods to monitor trace levels and ensure consumer safety.

Objectives and Study Overview

This study aimed to develop and validate a quantitative GC-MS method for determining 15 phthalate esters in soft drinks at concentrations from 100 to 5 000 ng/mL. The approach employs liquid-liquid extraction and selected ion monitoring (SIM) to achieve high sensitivity and specificity.

Methodology and Instrumentation Used

Sample preparation involved spiking 5 mL of drink with phthalate standards at 300 and 1 000 ng/mL, followed by extraction with dichloromethane containing benzyl benzoate as an internal standard. Stringent use of glassware and avoidance of plastics minimized background contamination.

• Gas Chromatography: Thermo Scientific TRACE GC Ultra with TraceGOLD TG-5MS column (30 m × 0.25 mm × 0.25 µm), helium carrier gas, oven program 80 °C (1 min) to 320 °C at 10 °C/min (8 min hold).
• Mass Spectrometry: Thermo Scientific ISQ single quadrupole in SIM mode, EI ionization at 70 eV, transfer line 300 °C, source 260 °C.
• Autosampling: Thermo Scientific TriPlus Autosampler and eVol sample dispensing system.

Main Results and Discussion

Chromatographic separation of all 15 phthalates was achieved within 25 min. Calibration curves for each compound exhibited excellent linearity (R2 > 0.99). Recoveries ranged from 66–111% at 300 ng/mL and 71–118% at 1 000 ng/mL; lower recoveries for higher-molecular-weight phthalates were attributed to adsorption losses.

Benefits and Practical Applications

This method delivers high sensitivity and reproducibility for routine screening of phthalates in beverage quality control and regulatory compliance. The low-bleed GC column minimizes background interference and enhances detection limits.

Future Trends and Opportunities

• Incorporation of isotopically labeled internal standards to improve quantitation accuracy.
• Automation and miniaturization of sample preparation to reduce contamination and solvent use.
• Adaptation of the method to other food, environmental, and biological matrices.
• Use of high-resolution mass spectrometry for broader screening of emerging plasticizers.

Conclusion

A robust GC-MS protocol using TraceGOLD TG-5MS and SIM detection was developed, demonstrating reliable quantification of phthalate esters in soft drinks with strong linearity and acceptable recovery rates.

References

• EU Commission JRC Technical Notes. Determination of bis-(2-ethylhexyl)phthalate (DEHP) in sports drinks by isotopic dilution HS-SPME-GC-MS.