Zeitschrift für Chromatographie und Trenntechniken
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Determination of Methadone in Human Urine Using Salting-Out Effect and Dispersive Liquid-Liquid Microextraction Followed by HPLC-UV

Reza Akramipour, Mitra Hemati, Simin Gheini, Nazir Fattahi and Hamid Reza Ghaffari

The salting-out effect combined 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 drug in urine samples. Methadone was employed as model compound 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 saltingout effect. The produced droplets go up through the remained mixture and collect as a separated layer. Then, undecanol (extraction solvent). In the second step, the 5.00 mL K2CO3 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 2-2000 μg L-1 and limit of detection (LOD) is 0.7 μg L-1.  the collected acetonitrile is removed with a syringe and mixed with 30.0 μL-1  .The extraction recovery and enrichment factor were 83% and 140%, respectively. Repeatability (intra-day) and reproducibility (inter-day) of method based on seven replicate measurements of 100 μg L-1 of methadone were 4.1% and 5.3%, respectively. The relative recoveries of urine samples spiked with methadone are 92%-106%.