Modern extraction techniques.

The central role of extraction during a chemical analysis compounds a critical review of developments in the field. Thousands of articles annually list “extraction” as a key word (about 2500 articles per year when searching only keywords for English chemistry journal articles). Consequently, narrowing the topic of this review is highly selective since about 10 000 articles survived the initial literature search. Hence, this review focuses on the most significant new developments and advances in the 2006-2009 calendar years, since the previous review (1). Articles focusing on applications were generally not considered in this review. The major trends in the field of extractions for chemical analysis appear to be the use of ionic liquids; development of electrically assisted extractions; alternative phases (including monoliths), quantitative methods, and geometries for sorptive extractions; approaches to membrane-based extractions; and single-drop and related lowvolume microextraction approaches. This represents a change from the trend of developing enhanced methods based on the application of energetics, a field which has perhaps developed to some state of maturity. These new trends represent the bulk of this Review. In addition to development and fundamental research articles, key reviews are highlighted to draw the reader’s attention to other state of the art discussions.