Acetaldehyde, Benzene, and Limonene in Recycled PET (rPET) Bottles by Headspace-GCMS

Importance of the Topic

Recycled polyethylene terephthalate (rPET) is widely used in food contact packaging. Volatile organic compounds such as acetaldehyde, benzene, and limonene may migrate from rPET into foods and beverages, posing potential safety and sensory quality risks.

Aims and Overview of the Study

This study demonstrates a headspace GCMS method for the qualitative and quantitative determination of acetaldehyde, benzene, and D-limonene in rPET bottles using a static headspace autosampler coupled with a single quadrupole mass spectrometer.

Instrumentation Used

• Headspace autosampler HS-20 NX (Loop Model)
• Gas chromatograph mass spectrometer GCMS-QP2050 with Nexis GC
• Column SH-PolarWax (30 m × 0.32 mm i.d. × 1.0 μm)
• LabSolutions software for data acquisition and processing

Methodology and Sample Preparation

Six commercial rPET bottle brands were cut into 5–8 mm pieces. Each 1.0 g sample was placed in a 20 mL headspace vial.
Calibration standards of acetaldehyde, benzene, and D-limonene were prepared in acetone over seven levels. Two microliters of each standard were added to vials containing 1 g of matrix to yield concentrations from 125 to 8000 ng/g for acetaldehyde and proportional ranges for the other analytes.
Headspace conditions: oven at 80 °C for 30 min with nitrogen pressurizing gas at 80 kPa. GC conditions: helium carrier gas, split ratio 20, temperature ramp from 35 °C to 230 °C. MS conditions: ion source at 200 °C, interface at 230 °C, acquisition in Fast Automated Scan/SIM (FASST) mode.

Main Results and Discussion

Limits of quantitation (LOQ) at S/N of 10 were 73.8 ppb for acetaldehyde, 0.54 ppb for benzene, and 1.42 ppb for D-limonene. Detection limits (LOD) at S/N of 3.3 were 24.4, 0.18, and 0.46 ppb, respectively.
Calibration curves exhibited excellent linearity with R² > 0.999 across all seven levels. Repeatability studies (n = 6) yielded %RSD values below 3.5% for each analyte.
In real samples, acetaldehyde was detected at 26.8 to 167.1 ng/g (well below the EU specific migration limit of 6000 ng/g). Benzene was not detected in any sample. D-limonene appeared at trace levels up to 0.6 ng/g. Spike recovery tests in two rPET samples returned 97%–117% recoveries, confirming method accuracy.

Benefits and Practical Applications

• Minimal sample preparation without solvent extraction
• High sensitivity and low detection limits for regulatory compliance
• Simultaneous qualitative confirmation and quantitative analysis in a single run using FASST acquisition
• Robust performance for routine quality control in food contact material production

Future Trends and Opportunities

Integration of headspace GCMS methods with automated online sampling to further reduce manual handling.
Expansion of analyte scope to other non-intentionally added substances in recycled plastics.
Adoption of high-resolution mass spectrometry for enhanced confirmation of unknown migrants.
Development of inline monitoring systems for real-time quality assurance in recycling processes.

Conclusion

The HS-20 NX headspace autosampler coupled with the GCMS-QP2050 delivers reliable, sensitive, and rapid analysis of acetaldehyde, benzene, and D-limonene in rPET bottles, supporting regulatory compliance and ensuring consumer safety.

References

1. Thoden van Velzen EU Brouwer MT Stärker C Welle F Effect of recycled content and rPET quality on the properties of PET bottles part II Migration Packaging Technology and Science 2020 33(9) 359–371
2. Coniglio MA Fioriglio C Lagana P Non Intentionally Added Substances in PET Bottled Mineral Water SpringerBriefs in Molecular Science 2019 1–66
3. European Commission Commission regulation (EU) No 10/2011