For the analysis of associated cations and sulfur, a Varian 715-ES (Agilent Technologies, USA) or an iCAP 7000 instrument (Thermo Fisher Scientific, USA) was used. The external calibration covered a range from 0.25 -50 mg/L and was prepared using standard solutions of potassium, sodium, calcium and sulfur. For ICP-OES analysis, carrageenan solutions with a concentration of 1 mg/mL were used. The solutions were prepared in 1 % (v/v) nitric acid and had a total volume of 10 mL.