Extraction methods are determined by the nature of the matrix, the drug to be isolated and the availability of equipment, staff and economic resources. This review critically describes the main extraction techniques commonly known as 'Liquid-Liquid' (LLE), those using modified Infusorial Earth (IE), Solid Phase Extraction (SPE), Solid Phase Micro Extraction (SPME) and Supercritical Fluids Extraction (SFE). Technical, economic, staff training and equipment-related aspects are assessed. All of them have advantages and limitations in their application. Generally, each technique, if properly chosen, meets the aim of isolating the analyte of interest. Nowadays, the techniques most often used are the LLE, the IE and the SPE, the use of which is growing day by day. The most recently developed technique, the SPME, is being more frequently used in recent years owing to the development of new fibres, leaving the SFE as the least used, mainly due to the equipment requirements.
Keywords: liquid-liquid extraction, SPE, solid phase extraction, SPME, solid phase micro extraction, SFE, supercritical fluids extraction, drugs of abuse, biological media, drug abuse