Hydrogels as Novel and Efficient Materials in Sorbent-Based Sample Preparation Techniques.

Recently, the application of hydrogel materials in sample preparation techniques has increased dramatically. This review discusses application of hydrogels in the field of sample preparation and focuses on extraction techniques practiced with hydrogel materials as sorbent and coating materials, and discusses their synthesis route. After introducing hydrogels, their applications in a variety of solid phase extraction methods (as one of the types of sample preparation techniques) are described. These methods include solid-phase microextraction (SPME), micro solid-phase extraction (µ-SPE) and magnetic solid-phase extraction (MSPE), in which hydrogels are used as the main adsorbent for the extraction and pre-concentration of heavy metals, pesticides, herbicides, insecticides, drugs and pigments. Also, the mechanism of adsorption of the above analytes by different hydrogels and the advantages of using hydrogels in the solid-phase extraction techniques are discussed. In the following, applications of pH-sensitive hydrogels as stimuli-responsive polymers, are discussed in the sample preparation field. Finally, conclusions and future perspectives are covered in the last section that will be very helpful for future studies.