Validation of ultrasonic extraction method for the quantification of phthalates in poly (vinyl chloride) and polypropylene matrices at low concentrations by gas-chromatography time of flight mass spectrometry (GC-TOFMS)

Phthalates are used as plasticizers in the manufacturing of plastics to increase their flexibility. Phthalates are endocrine disruptors and given their potential toxicity and widespread use, many countries have implemented strict regulations on their usage. A rapid gas chromatography time-of-flight mass spectrometry (GC-TOFMS) analytical method was developed for the determination and quantification of six regulated phthalates. Three extraction methods were investigated including two standard techniques; a dissolution method and a Soxhlet method (EN 14372:2004E). These two standard methods were compared to a simpler ultrasonic extraction method. The recoveries and accuracy of the measurements were assessed by analyzing a polypropylene (PP) certified reference material (matrix CRM) and spiked polyvinyl chloride (PVC) samples. The ultrasonic extraction method resulted in better recoveries (>80%) when compared to the dissolution method. The results obtained from extracting the CRM using the ultrasonic, dissolution and Soxhlet extraction methods were within the certified ranges. The dissolution method occasionally retains the phthalates during precipitation, leading to lower recoveries and inconsistent performance. The ultrasonic extraction method is simpler, uses less solvent and is less time consuming when compared to the conventional Soxhlet extraction method. The ultrasonic extraction method can confidently be used for the accurate quantification of the regulated phthalates in plastics at concentration levels ten times below the European Union regulated limits.