A sorptive extraction layer for immobilized liquid extraction of target molecules preferably from biological samples is disclosed. The sorptive extraction layer is mainly composed of ethylene-acrylate-copolymer. Preferably, microplate wells are at least partially coated with such a sorptive extraction layer. There is also disclosed a method of extracting target molecules preferably from biological samples. According to this method, immobilized liquid extraction is carried out with a sorptive extraction layer which is mainly composed of ethylene-acrylate-copolymer.