ABSTRACT
Some elements such as arsenic, antimony, bismuth, selenium, mercury, lead and tin can exist in solid matter in both inorganic and organic forms. The organic forms of the element may originate either by direct contamination of the solid by organic compounds of industrial origin or by naturally occurring biomethylation processes whereby inorganic forms of metals such as mercury and selenium are converted to the organic form, for example, in fish tissues or in sediments. Suitable handling procedures both during sampling and during analysis are necessary to avoid losses of metals in such instances.
