Simultaneous Determination of 21 Specific Elements in Typical Degradable Plastic Products by ICP-MS and Corresponding Safety Risk Analysis

ICP-MS was used to determine the 21 specific elements (boron, magnesium, aluminum, titanium, chromium, manganese, iron, cobalt, nickel, copper, zinc, arsenic, molybdenum, cadmium, strontium, tin, antimony, selenium, barium, merary and lead) introduced by various additives in the production process of 24 plastic products, including polyolefin-based and fully bio-based degradable express bags, degradable agricultural films, degradable shopping bags, and degradable lunch boxes. Furthermore, the safety risk level of each element in different products was analyzed according to the relevant standards. The samples were cut into pieces, frozen and pulverized, and an aliquot (0.3-0.5 g) was digested by microwave with 7 mL of nitric acid and 2 mL of 30% (mass fraction) hydrogen peroxide solution under temperature-programmed conditions. After the volume of the digestion solution was concentrated to 1 mL by removing the acid, and 1 mL of nitric acid was added. The solution was diluted to 50 mL with water, and filtered by a 0.22 μm filter membrane, and the filtrate was used to analyze by ICP-MS. It was shown that linear relationships between values of mass concentration and emission intensity of the 21 specific elements were kept in definite ranges, with detection limits (3S/N) of 0.03-0.2 μg·L^-1. Recoveries obtained by addition standard method was in the range of 94.2%-101%, and RSDs (n=5) of the determined values ranged from 0.47% to 9.8% As the proposed method was used for the analysis of actual samples, the 21 specific elements were detected to varying degrees. Detection amounts of mercury element in 6 batches of 3 types and selenium element in 11 batches of 4 types of samples exceeded the limits specified by the relevant standard. The contents of aluminum, iron, strontium and barium in fully bio-based products were generally higher than those in polyolefin-based products; the contents of most specific elements in the non-food contact products (degradable express bags, degradable agricultural films and degradable shopping bags) were generally higher than those in the food contact products (degradable lunch boxes). The detection amounts of titanium and magnesium elements in some products were too high, and the 8 elements (copper, zinc, cobalt, iron, manganese, tin, antimony and barium) had certain migration risks. The elements were not fully covered by limit requirements of relevant standards, and the current standards did not distinguish between the food contact products and non-food contact products. Therefore, it was recommended to consider the above situation in the subsequent revisions.