Determination, Spatial Variation and Distribution of Iodine in Fish

Abstract

Iodine is a very important essential trace element and marine fish is one of the rare natural food containing relatively large amounts of iodine. In this study a fast and reliable determination method of iodine in marine species has been developed and validated. The method based on a procedure of Gu et al. 18) published in 1997 and avoids ashing of the sample which often leads to iodine losses. Furthermore, various biological factors, effecting the iodine content in fish have been studied and the distribution in fish muscle was analysed. The iodine content of various flat, lean and fatty fish species from different fishing grounds has been compared, yielding no clear indication of a relation of iodine concentration to the fishing ground. But large variations were found between cod samples in fishes of a single catch. Distribution within fish muscle showed an iodine gradient, decreasing from skin to the inner part of the fillet and iodine levels in the skin of marine fishes can be up to twentifold of the content of the muscle tissue, depending on the species. No differences were observed between left and right fillets, ventral and dorsal parts and head and tail parts of cod fillets, respectively.