Surfactant-assisted dispersive liquid–liquid microextraction followed by high-performance liquid chromatography for determination of amphetamine and methamphetamine in urine samples

A novel surfactant-assisted dispersive liquid–liquid microextraction (SADLLME) based on solidification of floating organic drop (SFO) combined with high-performance liquid chromatography-ultraviolet detection (HPLC-UV) has been proposed for extraction and determination of amphetamine (AM) and methamphetamine (MA) in urine samples. 1-undecanol and sodium dodecyl sulfate (SDS) were used as extracting solvent and disperser, respectively. Face-centered central composite design (FCCCD) was used for optimization of several factors affecting extraction recovery. The optimal conditions were pH = 6.4, volume of extracting solvent V = 31.0 μL, 0.08 CMC as surfactant concentration, and the amount of NaCl for ionic strength was 0.3% (W/V). The limits of detection (LODs, S/N = 3) of the extraction method were 2 for AM and 3 μg L−1 for MA, with the enrichment factors (EFs) of 56 and 48 folds, respectively. The relative standard deviation (RSD %) for n = 3 was below 5.6% and a good linearity (R2 > 0.991) in the range of 10–2000 μg L−1 was observed. The application feasibility of SFO-SADLLME-HPLC-UV in real sample was investigated by analyzing different real samples and satisfactory results were obtained.