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Micro‐extraction techniques in analytical toxicology: short review
Author(s) -
Flanagan R. J.,
Morgan P. E.,
Spencer E. P.,
Whelpton R.
Publication year - 2006
Publication title -
biomedical chromatography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.4
H-Index - 65
eISSN - 1099-0801
pISSN - 0269-3879
DOI - 10.1002/bmc.671
Subject(s) - chemistry , chromatography , extraction (chemistry) , analyte , protein precipitation , derivatization , acetic acid , salting out , context (archaeology) , solvent , high performance liquid chromatography , liquid–liquid extraction , sample preparation , organic chemistry , aqueous solution , paleontology , biology
This paper discusses new developments in plasma micro‐extraction techniques in the context of established micro‐extraction and protein precipitation methodology. Simple liquid–liquid solvent extraction (LLE) of plasma with direct GC or HPLC analysis of the resulting extract has been used for many years. Butyl acetate and methyl t ‐butyl ether (MTBE) give efficient extraction of many drugs and metabolites from small volumes of plasma or whole blood at an appropriate pH, and form the upper layer, thus simplifying extract removal. Butyl acetate does not interfere with NPD, ECD or MS in GC, whilst MTBE has a relatively low UV cutoff (220 nm). Thus, HPLC eluents that use a high proportion of an organic component allow MTBE extracts to be analysed directly. ‘Salting‐out’ and extractive derivatization using acetic anhydride or phenylboronic acid can be used with appropriate analytes. As regards protein precipitation, an important consideration is lowering the pH, although this is not feasible with acid‐labile analytes. More recent developments include sold‐phase micro‐extraction (SPME) and liquid‐phase micro‐extraction (LPME). This latter technique especially may prove invaluable as analytes that cannot easily be extracted with LLE can be isolated simply at low cost with a minimum of apparatus. Copyright © 2006 John Wiley & Sons, Ltd.