Speciation of 38 elements in eight GSJ geochemical sedimentary reference materials determined using a sequential extraction technique

A sequential extraction procedure developed by the European Community Bureau of Reference (BCR) was applied to eight sediment geochemical reference materials provided by the Geological Survey of Japan, AIST (JLk-1, JSd-1-4, JMs-1, JMs-2, and JSO-1). The study aimed to provide reference materials of widely varied geological materials in order to enhance the utility of the sequential extraction procedure in environmental studies. The concentrations of 38 elements extracted by BCR protocols were determined for the eight reference materials. The BCR scheme is designed to extract elements of the intended phase using acetic acid (step 1), hydroxylammonium chloride (step 2), and hydrogen peroxide and ammonium acetate (step 3). The residue of the step 3 extraction was further digested using hydrofluoric acid, perchloric acid, and nitric acid (step 4). The relative standard deviations of elemental concentrations in each extraction stage were generally < 30% for steps 1 and 3 and < 20% for steps 2 and 4. The sums of the elemental concentrations for the four steps (the total recoveries) ranged from 70% to 100% of the bulk compositions. The speciation of elements in the reference materials obtained by BCR protocols was strongly affected by sediment origin, mineralogical composition, sedimentary environment, and anthropogenic activity. Accordingly, sequential extraction based on the BCR procedure is effective for environmental studies. Eight geochemical reference materials certified/recommended for bulk composition are now further available as reference materials for the sequential extraction procedure.