Deep eutectic solvents in analytical sample preconcentration Part B: Solid-phase (micro)extraction

One of the key challenges of modern analytical chemistry is the monitoring of trace amounts of contaminants using sensitive and selective instrumental techniques. Due to the variety and complexity of some samples, it is often necessary to properly prepare a sample and to perform a preconcentration of trace amounts of analytes. In line with the principles of Green Analytical Chemistry (GAC), it is important for an analytical procedure to reduce labor and time consumption and to decrease the use of volatile and hazardous solvents. Therefore, solvent-free extraction techniques, such as SPE, & mu;SPE, SPME and their various modifications, which are mainly aimed at increasing their "greenness", have been very popular for many years. Deep eutectic solvents fit perfectly into GAC principles, which is why they have been used as extractants in liquid-phase microextraction techniques for a long time. This review is a follow-up to our recently published article on the use of deep eutectic solvents (DESs) in liquid-phase microextraction techniques and summarizes the most important applications of DES in solid-phase (micro)extraction techniques.