Membrane-based extraction techniques offer efficient alternatives to classi
cal sample preparation techniques. In this review a number of examples from
the fields of environmental and biomedical analysis are discussed. High se
lectivity and enrichment factors, as well as the possibility of automated i
nterfacing to chromatographic and other analytical instruments, are shown f
or quantitative analysis. (C) 1999 Elsevier Science B.V. All rights reserve
d.