In recent years, bead injection (Fig. 2B) strategy has been proposed to overcome the drawbacks. Following
this strategy, bead sorbents can be packed and discarded in a flow system by multisyringe pump in each analytical cycle. Hence, SPE in renewable fashion is online coupled with LC, eliminating any possibility of carryover between consecutive runs [5,6]. Based on this bead injection system, multimodal SPE involving different renewable sorbents can be hyphenated to LC, and the schematic diagram of the system is shown in Fig. 3.