Determination of Phenol in Five Food Plastic Packaging Materials by Rapid Synergistic Cloud Point Extraction Coupling with Fluorescence Spectrophotometry

A rapid synergistic cloud point extraction method coupling with fluorescence spectrophotometry was developed for preconcentration and determination of trace amounts of phenol from food plastic packaging materials. The linear-chain and non-ionic surfactant polyethylene glycol 6000 was selected as the extractant. The octanol was used as a cloud point revulsant and synergistic reagent with anhydrous sodium sulfate to lower the cloud point temperature of polyethylene glycol 6000 to room temperature (about 20℃) within 3 min. The factors influencing the extraction efficiency of phenol, including the mass concentration of PEG 6000, the mass of anhydrous sodium sulfate, the volume of octanol, and the pH of solution were optimized. As a result, the optimum conditions for extraction of phenol were as follows:the pH of solution 6.0;0.2 g/mL PEG 6000 8.0 mL;mass of anhydrous sodium sulfate 3.0 g and volume of octanol 5.0 mL. Under these conditions, a good linearity (R²=0.9998) was obtained in the range of 0.02~1.60 μg/mL with the limit of detection of 0.0064 μg/mL. The method also showed excellent repeatability in the view of low relative standard deviation (RSD=4.49%, n=8) and obtained high extraction efficiency (89.8%) in a 50 mL sample. The recoveries were between 90.5%~109.5%. Only sample 2 of five kinds of food plastic packaging materials was found to contain phenol 0.0310 μg/mL, which did not exceed the standard, and the other four materials were not detected to contain phenol. This method was simple, rapid, time-saving and sensitive. It was successfully applied to determinate phenol in five food plastic packaging materials.