Innovations in sol-gel microextraction phases for solvent-free sample preparation in analytical chemistry

Sol-gel column technology with its inherent ability to provide surface-bonded hybrid organic-inorganic polymer coatings and monolithic beds has gained remarkable popularity in analytical microextraction, thanks to chemical stability and diversity of the extracting phase it offers in solvent-free sample preparation. Because of this and other advantages, over the last two decades sol-gel technology has been a vehicle of innovation for micro/nano sample preparation in analytical chemistry. A diverse array of novel advanced sol-gel material systems with unique selectivity, enhanced extraction sensitivity and higher thermal, mechanical and solvent stability have already emerged. The commercial availability of a growing number of inorganic/organically modified sol-gel precursors and sol-gel active organic polymers, coupled with the ability to form surface-bonded organic-inorganic coatings/monolithic beds with controllable porosity and tunable selectivity have firmly placed sol gel technology in the forefront of analytical sample preparation and related research. The sol-gel derived advanced material systems have been shown to be highly effective in solvent free/solvent minimized sample preparation for a wide variety of analytes with biological, environmental, food, pharmaceutical, bio-analytical, and forensic significance. The current review discusses the basic principles of sol-gel technology, use of major inorganic/organically-modified sol-gel precursors and sol-gel active polymers to create sol-gel hybrid material systems. It highlights their physico chemical attributes favorable for micro/nano-sample preparation. Special emphasis is given to innovations in sol-gel extraction media, and to the novelty and the diversity of the formats of sol-gel materials used in sample preparation. (C) 2013 Elsevier Ltd. All rights reserved.