ICP-OES Method for the Determination of Trace Metals in Nori Seaweed: Application for the Analysis of Different Samples from Different Countries

Over the past few decades, seaweed consumption and use significantly have grown, especially in Europe where a health-food trend has increased. Seaweed contains nutrients including proteins, vitamins, minerals, and dietary fiber. The health benefits of seaweed are mostly attributed to its bioactive molecules, which include sterols, polysaccharides, and polyphenols. This study aimed to the simultaneous determination of Cd, Ba, Zn, Pb, Cu, Cr, Rb, Se, Sr, and V in nori seaweed collected from Korea, Japan, and China. The method was optimized and then validated using inductively coupled plasma optical emission spectroscopy (ICP-OES). The optimized parameters include the following conditions: nebulizer argon flow rate and incident power. The optimized extraction procedure consisted of a mixture of 7 mL HNO₃-H₂O (3:2, v/v) and 1 mL of H₂O₂. Analytical lines were chosen after optimizing the instrument and were free of spectrum interferences. The intra- and inter-assay precision ranged from 1.36 to 5.22% and 0.95–4.35%, respectively, depending on the metal being studied. LOD, LOQ, linearity, and sensitivities were also investigated. The metal concentrations were determined in six samples of nori seaweed from Korea, Japan, and China. The results indicated a relative increase in the concentration of specific heavy metals such as Cd and Pb according to the European Food Safety Authority (EFSA), while the remaining metals were within the safe limits. Finally, the proposed method was successfully employed to analyze metals in nori seaweed found in the Riyadh market and highly consumed by people.