Simultaneous chiral separation of tramadol and methadone in tablets, human urine, and plasma by capillary electrophoresis using maltodextrin as the chiral selector

The chiral separation has gained importance in pharmaceutical industry since more than half of the drugs currently in use are chiral and about 90% of the last ones are marketed as racemates consisting of an equimolar mixture of two enantiomers [1]. Various analytical techniques have been successfully employed for the enantioseparation such as capillary electrophoresis using various chiral selectors [2].This paper focuses on the simultaneous stereoselective separation of tramadol and methadone enantiomers using Maltodextrin as the chiral selector in a CE-based analysis. The best separation for the both enantiomers were achieved on an uncoated fused-silica capillary at 25 °C using 100 mM phosphate buffer (pH 8.0) containing 20% (w/v) maltodextrin with dextrose equivalent of 4–7 and an applied voltage of 16 kV (Fig. 1). The relative standard deviations (n = 3) of 20 μg mL−1 TRA and MET were 2.28 and 3.77 %, respectively. The detection limits were found to be 2 μg mL-1 for TRA and 1.5 μg mL-1 for MET. The developed method was successfully applied to the measurement of drugs concentration in their tablets, urine and plasma samples.