Effects of sediment, seawater, and season on multi-element fingerprints of Manila clam (Ruditapes philippinarum) for authenticity identification

• Some elements in clams had significant differences between different regions.
• Some elements in clams existed significant differences between different seasons.
• Mg, Cd, Sn, Ba, and Ce in clams are related to origin and less affected by season.
• The robust discriminant model of Jiaozhou Bay clam was built.
• The results may be helpful for geographical traceability of other aquatic products.

The objective of this study was to select suitable elements which reflect the link with geographical origin while are less affected by season to build robust discriminant models for the protection of Jiaozhou Bay clam by the multi-element fingerprinting technique. Manila clam (Ruditapes philippinarum), sediment, and seawater samples were collected from three major clam producing areas of China (Jiaozhou Bay, Nantong coast, and Dalian coast) in May and September 2014. The concentrations of 25 elements (Na, Mg, Al, etc.) were determined in all the samples. The data obtained was analyzed by analysis of variance, Pearson correlation, a radar plot, and stepwise linear discriminant analysis. The results demonstrated that the models built on five elements (Mg, Cd, Sn, Ba, Ce) are correlated with geographical origin and independent of seasonal variations, and can be used to completely differentiate Jiaozhou Bay clams from the samples from Nantong and Dalian.