Rapid and Portable Detection of Heavy Metals in Plastic Food Packaging Materials Using ED-XRF with Monochromatic Excitation and Fundamental Parameter Calibration

The presence of toxic metals in plastic packaging has been demonstrated to permeate foodstuffs, thereby posing a considerable threat to both food safety and human health.Considering relatively lower levels of heavy metals in various food plastic packaging materials, it is urgent to develop a sensitive, fast and portable analysis tool.In this study, a new portable energy dispersion X-ray fluorescence spectrometry (ED-XRF) with monochromatic excitation for the simultaneous determination of Pb, Cd, As, Cr, Ni, Sn, Cu, Ba, Sb and Zn in plastic packaging sample for the first time.By optimizing the full focused hyperbolic curved crystal and fundamental parameter (FP) calibration method, sensitive analysis was fulfilled with the detection limits (LODs) of 0.07-0.25 mg/kg, as well as the interference from complex plastic matrix and overlapping characteristic spectral lines of As K and Pb L were completely eliminated after the verification of a series of self-made plastic reference materials.For powdered or non-destructive plastic samples, each measurement time can be shortened to less than 10 min with the relative standard deviations (RSDs) < 5% at 7.2-136.8mg/kg and < 17% at 0.3-2.3mg/kg, respectively.The measurements by ED-XRF exhibited strong agreement with the microwave digestion ICP-MS approach.Therefore, the recommended portable ED-XRF method is characterized by sensitivity, accuracy and stability, and is extremely suitable for field monitoring of multi-elements in plastic food packaging samples to ensure the plastic quality and food safety.