Determination of amantadine in biological fluids using simultaneous derivatization and dispersive liquid–liquid microextraction followed by gas chromatography-flame ionization detection

•A simultaneous derivatization/DLLME method for extraction of amantadine is presented.•High EF and EnF are advantages of the method.•The proposed method has a low detection limit and a wide linear range.•The method shows relatively low matrices effects in the complex biological matrices. A one-step derivatization and microextraction technique for the determination of amantadine in the human plasma and urine samples is presented. An appropriate mixture of methanol (disperser solvent), 1,2-dibromoethane (extraction solvent), and butylchloroformate (derivatization agent) is rapidly injected into samples. After centrifuging, the sedimented phase is analyzed by gas chromatography-flame ionization detection (GC-FID). The kind of extraction and disperser solvents and their volumes, amount of derivatization agent and reaction/extraction time which are effective in derivatization/dispersive liquid–liquid microextraction (DLLME) procedure are optimized. Under the optimal conditions, the enrichment factor (EF) of the target analyte was obtained to be 408 and 420, and limit of detection (LOD) 4.2 and 2.7ngmL−1, in plasma and urine respectively. The linear range is 14–5000 and 8.7–5000ng/mL for plasma and urine, respectively (squared correlation coefficient≥0.990). The relative recoveries obtained for the spiked plasma and urine samples are between 72% and 93%. Moreover, the inter- and intra-day precisions are acceptable at all spiked concentrations (relative standard deviation