To overcome this constraint, application of novel polymeric phases with higher affinity for more polar compounds have been proposed in different microextraction techniques [18].
Such developments have been typically occurred in SPME [19,20] and SBSE [21e23] procedures.
Moreover, thin films of polyacrylonitrile (PAN) [24], poly(vinylidene fluoride) [25], polyimide nanofiber [26] and chemically modified cellulose paper [27] have been applied as the polar sorptive phase in TFME
Recent researches using special configurations of sorptive phases such as disk, film or membrane have displayed that there is a possibility to avoid desorption step by performing a direct solidstate spectrophotometric or spectrofluorimetric analysis of the sorptive phase after extraction [28e30].
Since these configurations provided a larger exposed surface area of the sorptive phase, their extraction efficiencies and load abilities were increased and as a result, sensitivity of these techniques were enhanced without dedication to sampling time compared to other microextraction procedures.
Additionally, both desorption step and solvent evaporation prior to determination have been eliminated using these technique, and hence provides excellent recoveries via a single-step sample preparation approach which is extremely appealing for routine analysis of numerous samples.