Determination of Rare Earth Elements in Navel Oranges from Different Geographical Regions of China by Inductively Coupled Plasma-Mass Spectrometry

There are three major production bases of navel oranges in China, including Southern Jiangxi Province, Southern Hunan Province, and the Three Gorges District of the Yangtze River. Southern Jiangxi and Southern Hunan are also famous for rare earth elements that are ionic, making them easily passed from soil to plants and fruits. To test the relative enrichment of rare earth elements in navel oranges from these production sites, ICP-MS analysis was performed following a microwave digestion procedure. The concentrations of La, Ce, Pr, and Nd in navel orange peels from Southern Jiangxi and Southern Hunan (1.26–1.86 µg g−1) were much higher than results from the Three Gorges (0.23–0.46 µg g−1). Moreover, yttrium is relatively enriched (0.25–0.29 µg g−1) in navel orange peels from Southern Jiangxi at concentrations almost twice that from Southern Hunan (0.15 µg g−1). The various concentrations and distribution of rare earth elements offers the possibility of traceability and authentication of navel oranges. Meanwhile, navel orange peels from Southern Jiangxi posed no risk in consumption, based on the maximum limit level (≤0.7 µg g−1, wet weight) of rare earth elements in food issued in China (GB 2762-2005).