Membrane-based extraction techniques adhere to the principles of Green Analytical Chemistry. The presence of membrane in these extraction techniques not only ensures the cleanliness and integrity of the extracting phase but also it expands the primary contact surface area of the acceptor phase so that mass transfer of the analytes from the donor phase to the acceptor phase occurs rapidly, resulting in faster extraction equilibrium and higher preconcentration factor. Both solid sorbents and liquid solvent phase can be protected by the membranes. The significance of the membrane in membrane-based extraction techniques is obvious especially when biological and environmental samples are processed. Generally, these samples need one or more pretreatment processes such as filtration, protein precipitation, and centrifugation prior to subjecting the samples to the extraction techniques. These extra steps are laborious, time consuming and often result in substantial loss of the target analytes. Protecting the sorbents by the membrane allows total elimination of the sample pretreatment process. The current chapter highlights different membrane-based extraction techniques in the light of Green Analytical Chemistry.
