Considerations for the Determination of Trace Concentrations of Arsenic in Environmental Water Samples

Studies of the occurrence, distribution and aqueous geochemistry of arsenic in the environment requires accurate and sensitive analytical measurements. In addition to the determination of total arsenic concentrations, speciation of the form in which arsenic occurs plays a major role in its chemical reactivity and toxicity. Determination of speciation includes: the distribution of oxidation states (i.e. AsO2, arsenite and AsO4, arsenate); the nature of molecular compounds incorporating arsenic; and physical forms of arsenic, such as, dissolved, colloidal or particulate. Because of its normally low concentration in natural systems, analytical methodology usually requires both high sensitivity and specificity.