a biocompatible coating , such as for a fiber , for solid phase microextraction of a small molecule of interest from a matrix , with the coating having an extraction phase including spme particles having pores dimensioned to absorb the small molecule of interest from the matrix and a biocompatible polymer being a polyacrylonitrile or a co - polymer of polyacrylonitrile that completely covers the spme particles and homogeneously distributing the spme particles therein and having reduced adsorption of proteins or macromolecules onto the spme particles and allowing the spme particles to extract the small molecule of interest from the matrix .