This book gives a survey on the latest most representative progress concerning ionic liquids and polymeric ionic liquids in solid phase extraction, from their fundamental approaches to their applications in solid phase extraction. It also highlights the recent advancements in IL-SPE and MSPE. Recently Ionic liquids (ILs) have been widely studied due to their interesting structures and unusual properties[1]. These non-molecular compounds exhibit melting points below 100 C, low to negligible vapor pressure at room temperature, high chemical stability and wide electrochemical windows.