Validation of an ICP-OES method for macro and trace element determination in Laminaria and Porphyra seaweeds from four different countries

An Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) method for speedy simultaneous determination of 12 elements (Al, Ba, Ca, Cu, Fe, K, Mg, Mn, Na, P, Sr and Zn) in seaweeds used as human food was optimized and then validated according to Eurachem guidelines. First, instrumental parameters (nebulizer argon flow rate and incident power) were optimized and then analytical lines free from spectral interferences were selected. The method was validated using biological Certified Reference Materials (CRMs). Intra- and inter-assay precision varied from 0.79% to 5.74% and from 2.48% to 8.57%, respectively, depending on the element studied. Within the experimental error, concentrations measured for each element coincided with certified values. Sensitivities, linearity and detection and quantification limits were also determined. Samples of seaweeds (Porphyra and Laminaria) from France, Spain, Korea and Japan were analyzed by using the optimized and validated method. Some considerations on element composition of analyzed samples were made. Seaweeds from the Korean and Japanese coasts tended to display the highest concentrations of P and Al. In contrast, French Porphyra samples showed the lowest levels of Ba, Cu, Fe and Mn. Because great differences in element concentrations were observed due to costal origin and genus, any generalization regarding the algal mineral content may be considered misleading and scientifically inappropriate.