A critical outlook on recent developments and applications of matrix compatible coatings for solid phase microextraction

The introduction of matrix compatible solid phase microextraction (SPME) coatings in recent years has enabled analysis of complex matrices by direct immersion, and thus has overcome some of the challenges and limitations related to headspace SPME. The advantages associated with direct immersion solid phase microextraction through the use of matrix compatible coatings has led to the advancement of research studies in food, environmental and biological matrices. This review provides an overview of the most recent developments and application of matrix compatible coatings to food, environmental and bioanalytical studies. Emphasis is given to the applications of commonly used matrix compatible materials such as polyacrylonitrile, polydimethylsiloxane, polymeric ionic liquids, polyaniline and polytetrafluoroethylene polymers. The suitability and advantages of these coatings in direct immersion microextractions are mentioned for some specific applications. In addition, the potential to directly couple matrix compatible microextraction devices to mass spectrometry is described together with applications in various complex matrices. Finally, the relevance of these matrix compatible coatings in facilitating in vivo and ex vivo bioanalytical studies, which in turn offer opportunities for metabolomics, lipidomics and exposome studies, is also discussed.