Interaction of Butanedioic and Hexanedioic Acid Bis-Hydrazides with Selected Essential and Hazardous Elemental Ions

Chemical speciation of metal ions in aquatic environments is one of the most important topics in the fields of environmental chemistry, analytical chemistry, Pharmacology, toxicology and geochemistry. The term "Chemical species" was defined1 in "IUPAC Recommendations-2000" as "a specific form of an element defined as to isotopic composition, electronic or oxidation state, and/or complex or molecular structure". Chemical speciation is "the distribution of an element amongst defined chemical species in a system". Speciation analysis is "the analytical activity of identifying and /or measuring the quantities of one or more individual chemical species in a sample". Speciation is generally determined through analytical data acquisition methods that measure free metal ion and/ or free ligand and/or free hydrogen ion concentration(s) in conjunction with thermodynamically based predicted models. Vigorous mathematical algorithms are used to refine the predicted model and to get the best-fit model that accounts for all the species in solution, satisfying all the mass balance equations and probed data. Species concentration distribution against pH of the solution, which relies on the local equilibria assumption and on experimentally determined formation constants, is then generated.