2018/8/24 · 1. Introduction Sample preparation is a key step in the whole analytical procedure. So far, various adsorbent-based extraction methods such as solid-phase extraction (SPE) [, , ], magnetic solid-phase extraction (MSPE) [4,5], solid-phase microextraction (SPME) [, , ], pipette-tip solid phase extraction [], in-syringe SPE [10,11] and tip microextraction (TME) [12,13] have been developed and