Analysis of Plasticizers in Medical Products by GC-MS with a Combined Thermodesorption - Cooled Injection System

Significance of the topic

The widespread use of plasticized PVC in medical devices raises concerns about the leaching of phthalate plasticizers, especially di-2-ethylhexyl phthalate (DEHP), into fluids intended for human use. DEHP and its metabolites have been linked to carcinogenicity, reproductive toxicity, and metabolic disruptions, making reliable detection in medical tubing critical for patient safety, particularly in vulnerable groups such as hemodialysis and critically ill patients.

Objectives and study overview

This study evaluated 34 types of medical plastic articles—tubing, syringes, infusion sets and storage containers—to identify and quantify volatile plasticizers and additives. The primary goal was to demonstrate a solvent-free, direct analysis approach for trace plasticizer detection and to assess potential patient exposure routes.

Methodology and instrumentation

A direct thermal desorption approach was employed using a combined thermodesorption unit (TDS-2) and a cooled injection system (CIS-3). Samples (≈10 mg) of each polymer were loaded into glass desorption tubes, thermally desorbed at temperatures up to 300 °C, and cryofocused at –150 °C in the CIS. Subsequent GC-MS analysis was performed on an HP 6890 gas chromatograph coupled to an HP 5972 mass selective detector.

Main results and discussion

Analysis revealed up to 30 distinct volatile components per sample. DEHP was the predominant plasticizer in flexible PVC articles, followed by diethyl phthalate (DEP), dibutyl phthalate (DBP) and others. Rigid polypropylene containers showed minimal phthalate content but contained hydrocarbons and antioxidants such as BHT. Notably, cyclohexanone, a diagnostic marker elevated in dialysis patients, was detected in dialysis tubing.

Benefits and practical applications of the method

• Eliminates solvent-related contamination risks
• Rapid, direct screening of solid and liquid medical materials
• High sensitivity for trace-level plasticizers and volatile additives
• Compatible with routine GC-MS workflows

Future trends and potential applications

Advancements may include automated sample handling, broader screening of emerging plasticizers, integration with high-resolution mass spectrometry for isomer differentiation, and deployment in regulatory compliance and quality control laboratories to monitor patient-contact materials in real time.

Conclusion

Direct thermal desorption coupled with cooled injection GC-MS provides an effective, contamination-free method for identifying plasticizers in medical devices. The frequent detection of DEHP in flexible PVC underscores the need for routine monitoring and potential replacement with safer alternatives to protect sensitive patient populations.

Použitá instrumentace

• Thermodesorption system: TDS-2 (Gerstel)
• Cooled injection system: CIS-3 (Gerstel)
• Gas chromatograph: HP 6890
• Mass selective detector: HP 5972

References

• Wahl H.G., Chrzanowski A., Ottawa N., Häring H.-U., Hoffmann A. Analysis of Plasticizers in Medical Products by GC-MS with Thermodesorption—Cooled Injection. AppNote 6/1996.
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