Method for determination of fatty acid amides in polyethylene packaging materials--gas chromatography/mass spectrometry.

A new method for determination of fatty acid amides in polyethylene packaging film was developed using gas chromatography/mass spectrometry (GC/MS). Liquid extraction, Soxhlet extraction ultrasonic-assisted extraction and pressurized solvent extraction (PSE) methods were compared and the results showed that pressurized solvent extraction was the best for extracting these compounds. After extraction, solvent was blown by nitrogen and a trifluoroethyl derivation step was carried out. The derivative compounds were identified and quantified by GC/MS using an HP-Innowax column. The retention times were 6.20 min for derivative hexadecanoamide, 8.56 min for derivative octadecanamide, 8.84 min for derivative oleamide and 13.68 min for derivative erucamide, respectively. The detection limits were 61.0 ng g(-1), 74.0 ng g(-1), 103.0 ng g(-1), and 105.0 ng g(-1), respectively, and the linearity were good. The proposed method was applied satisfactorily to determine these chemicals in different types of polyethylene samples.