Developement of a MEPS-GC-MS method for the determination of phthalates in PET packaging

The production of plastic materials has increased, reaching approximately 54 million tons in 2023 in the European Union alone. To ensure a high level of food safety, plastic food contact materials (FCMs) must comply with EU Regulation 10/2011[2]. Among the compounds potentially migrating from FCMs, phthalates, used as plasticizer during plastic production, have raised concerns due to their potential endocrine disruption and reproductive toxicity. Therefore, many manufacturers have introduced products labeled as “phthalate-free. In this study a green analytical method based on Micro Extraction by Packed Sorbent coupled with gas-chromatography-mass spectrometry (MEPS-GC-MS) was developed, optimized and validated to determine phthalates from polyethylene terephthalate (PET) cosmetic packaging labelled as phthalate-free, into food simulant B and D1. MEPS [1] is a miniaturized technique characterized by enhanced selectivity and preconcentration capability, enabling simultaneous extraction, preconcentration and clean-up of analytes. This technique aligns with the principles of Green Analytical Chemistry [2], as it minimizes both sample and solvent consumption, reduces waste and allows reuse of the extraction phase. Seven phthalates, namely DiBP, DBP, MPP, DPP, BBP, DCHP, DEHP and DnOP were selected as model compounds. An investigation was carried out to evaluate the influence of sorbent phase (C2, C8 and C18) and elution solvents (heptane, acetonitrile and tetrahydrofuran) on extraction performance. The best results were achieved with C18 as the sorbent and heptane as the elution solvent. Later, loading and elution cycles were optimized using a face-centered factorial design of experiment combined with the desirability function multicriteria method, resulting in 30 loading cycles and 3 elution cycles as optimal conditions for the extraction of all analytes. The optimized MEPS-GC-MS method was validated according to EURACHEM guidelines [3]. LOD and LOQ in the 0.63-290 ng/L and 2.1-960 ng/L range, respectively were obtained. Good precision and trueness were demonstrated with RDS% always lower than 8,2% and recovery rates in the 95,7(±2,6)– 116,3(±4,6)% range. Finally, the sustainability of the proposed method was assessed using AGREEprep, BAGI and CHEMS-1 tools. The obtained scores (0.51 for AGREEprep and 70.0 for BAGI) indicated good overall greenness, highlighting only a few critical aspects such as the limited number of samples processed simultaneously, the ex-situ sample preparation, and the energy efficiency of the analytical technique. The CHEMS-1 evaluation further confirmed the method’s environmental compatibility. Finally, the optimized method was applied for the determination of phthalates from “phthalate-free” cosmetic packaging. Three phthalates, namely DiBP (0.0032±0,0025 - 0.074±0,016 mg/kg), DBP (0,00093±0,00082 - 0,0426±0,0081 mg/kg) and DEHP (0,0083±0,0078 - 1,52±0,25 mg/kg) were determined in virgin and recycled PET samples. The developed method exhibited high sensitivity and selectivity, enabling trace-level determination of phthalates and demonstrating its potential applicability for quality control of phthalate-free plastics. REFERENCES [1] N. Riboni et al., Separations Vol. 10 (2023), 222. https://doi.org/10.3390/SEPARATIONS10040222. [2] Commissione Europea, Regolamento (UE) n. 10/2011 della Commissione, https://doi.org/http://data.europa.eu/eli/reg/2011/10/oj. [3] H. Cantwell (ed.) Eurachem Guide (3rd ed. 2025). Available from www.eurachem.org.