Atomic Spectrometry Update. Elemental speciation

Abstract

This is the first Atomic Spectrometry Update (ASU) to focus specifically on developments in elemental speciation and covers a period of 10 months from January 2008. Other ASU reviews^1–5 detail aspects of the research in this area, but our aim is to bring all of the work on this subject together in a single review. This new development comes as a result of the importance of the currency of the ASU reviews as a series. As a consequence of the continued and growing interest in the area of elemental speciation, which is evidenced by the volume of primary and review literature on the subject and the emergence of scientific meetings focusing on the topic, it was decided to instigate a radical change to the ASU series, culminating in the development of this new Update. Speciation has been considered by the International Union for Pure and Applied Chemistry (IUPAC) who have published guidelines⁶ for its definition, which are as follows: speciation analysis is the analytical activity of identifying and/or measuring the quantities of one or more individual chemical species in a sample; the chemical species are specific forms of an element defined as to isotopic composition, electronic or oxidation state, and/or complex or molecular structure; the speciation of an element is the distribution of an element amongst defined chemical species in a system. This review will therefore deal with all aspects of the analytical speciation methods developed for: the determination of oxidation states; organometallic compounds; coordination compounds; metal and heteroatom-containing biomolecules, including metalloproteins, proteins, peptides and amino acids; and the use of metal-tagging to facilitate detection via atomic spectrometry. Applications in the areas of environmental science, clinical and pharmaceutical analysis, food, industrial and related areas will be covered. The review will not specifically deal with operationally defined speciation, but will highlight other reviews which cover the work in this area. As with all ASU reviews, the coverage of the topic is confined to those methods that incorporate atomic spectrometry as the measurement technique. However, in the spirit of meeting the needs of the subject, we will incorporate material that is not strictly “atomic spectrometry”. For the most part, such procedures are those in which some form of molecular MS is the measurement technique. There is a growing role for this kind of MS either as the sole instrumental technique or quite literally, in parallel with an elemental detector. As the contents of this Update show, there is considerable activity in the development and application of methods of elemental speciation analysis, which for some elements and combinations of techniques is a mature field as shown by the extent to which relevant topics have been the subject of reviews and book chapters.