Solid-phase microextraction (SPME) method unify extraction, concentration and sampling into one single step. In SPME, a fused silica fiber is coated with a stationary phase and the fiber is exposed to an aqueous or gaseous sample till equilibrium is achieved between the analyte in the sample and the fiber. The analyte is then thermally desorbed from the fiber in the injection chamber of a gas chromatograph (GC) and analysed by mass spectrometer (MS).