This document describes a method for the determination of inorganic arsenic in algae and algae products by anion-exchange HPLC-ICP-MS following water bath extraction. The method is specifically designed for seaweeds containing inorganic arsenic and arsenosugar 408 (i.e. sulfate-arsinoylriboside). The peaks of inorganic arsenic and arsenosugar 408 are separated by gradient elution.

The method was initially tested and evaluated on the algae species Ascophyllum nodosum, Fucus vesiculosus and Saccharina latissima. Given the limited number of participating laboratories in the interlaboratory studies, this document is only validated for Ascophyllum nodosum and Saccharina latissima, but it can also be used for other algae species.