Combination of counter current salting-out homogenous liquid-liquid extraction and dispersive liquid-liquid microextraction as a novel microextraction of drugs in urine samples.

Abstract The counter current salting-out homogenous liquid-liquid extraction (CCSHLLE) joined with the dispersive liquid–liquid microextraction based on solidification of floating organic drop (DLLME–SFO) has been developed as a high preconcentration technique for the determination of different drugs in urine samples. Amphetamines were employed as model compounds to assess the extraction procedure and were determined by high performance liquid chromatography–ultraviolet detection (HPLC–UV). In this method, initially, NaCl as a separation reagent is filled into a small column and a mixture of urine and acetonitrile is passed through the column. By passing the mixture, NaCl is dissolved and the fine droplets of acetonitrile are formed due to salting-out effect. The produced droplets go up through the remained mixture and collect as a separated layer. Then, the collected acetonitrile is removed with a syringe and mixed with 30.0 μL 1-undecanol (extraction solvent). In the second step, the 5.00 mL K 2 CO 3 solution (2% w/v) is rapidly injected into the above mixture placed in a test tube for further DLLME–SFO. Under the optimum conditions, calibration curves are linear in the range of 1–3000 μg L −1 and limit of detections (LODs) are in the range of 0.5–2 μg L −1 . The extraction recoveries and enrichment factors ranged from 78 to 84% and 157 to 168, respectively. Repeatability (intra-day) and reproducibility (inter-day) of method based on seven replicate measurements of 100 μg L −1 of amphetamines were in the range of 3.5–4.5% and 4–5%, respectively. The method was successfully applied for the determination of amphetamines in the actual urine samples. The relative recoveries of urine samples spiked with amphetamine and methamphetamine are 90–108%.