Determination of Six Small-molecule Compounds in Polyethylene Terephthalate (PET) Used for Food Packaging by GC-MS
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Abstract:
A method for determination of six small-molecule compounds in food packaging material polyethylene terephthalate (PET) was developed in this study, using gas chromatography coupled with mass spectrometry. Methylene chloride ultrasonic-assisted extraction and dissolution methods in a mixed solvent of phenol/1,1,2,2-tetrachloroethane were compared and optimized. The extract was separated using a HP-5MS column, the analytes were detected by mass spectrometer, and retention time and peak area were used for qualitative and quantitative analyses, respectively. The results showed that the optimum conditions for methylene chloride ultrasonic extraction were as follows: solid to liquid ratio (m:V) 1:15, extraction time 30 min, and extraction cycle one time. A good linearity was found for six small-molecule compounds in the range of 0.05~2 mg/L, with the coefficients of determination greater than 0.9980. The limit of detection and the limit of quantitation were 0.1~25 μg/L and 1~25 μg/L, respectively. The recovery rates of spike concentrations of 200, 500, and 1000 μg/L were between 71.99% and 109.99%, relative standard deviations (RSDs) were between 0.01~8.20%; the intra-day and inter-day precisions were less than 4.74% and 5.86%, respectively. This method was used for the determination of six small-molecule compounds in 25 different types of commercial PET materials used for food packaging. Toluene, butylated hydroxy toluene (BHT), or di-(2-ethylhexyl) phthalate (DEHP) were detected in five samples, and the highest contents of toluene, BHT, and DEHP found, were 308.11 mg/kg, 500.31 mg/kg and 482.57 mg/kg, respectively. The advantages of this method include simple pre-treatment procedure, good separation, and high sensitivity, and this method can be used for routine determination of six small-molecule compounds found in PET materials.
