**4.2.2 Seaweed**

A gas chromatography (GC) method was reported for the trace analysis of I- in processed seaweed by Lin et al. (Lin et al., 2003). The method is based on the derivatization of aqueous iodide extracted from seaweed with 2-(pentafluorophenoxy)ethyl 2 (piperidino) ethanesulfonate in toluene using tetra-*n*-hexylammonium bromide as a phase-transfer catalyst.
