Speciation analysis of selenium in plankton, Brazil nut and human urine samples by HPLC-ICP-MS

► A method for selenium speciation in biological materials was described. ► The coupling HPLC-ICP-MS was used for this purposed. ► Selenomethionine and selenocystine were the species found in Brazil nuts. ► Selenocystine was found in urine samples. ► Differences were observed between men and women urine after Brazil nuts consumption.