Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction and Capillary Electrophoretic Determination of Tramadol in Human Plasma

Background: Tramadol, (±)-trans-2-[(dimethylamino) methyl]-1-(3-methoxyphenyl) cyclohexanol, is a synthetic centrally acting analgesic used in the treatment of moderate to chronic pain. Tramadol, like other narcotic drugs, is used for the treatment of pain and may also be abused. Its overdose can cause adverse effects such as dizziness, vomiting, and nausea. The aim of this paper is to develop a sample preparation method for the determination of tramadol in human plasma samples, followed by CE analysis. Methods: Ultrasound assisted-dispersive liquid-liquid microextraction using binary mixed extractant solvent (chloroform and ethyl acetate) was used for the extraction of one hundred microliters of tramadol spiked human plasma samples and in real human plasma samples obtained from the patients with abuse of tramadol. After evaporation of the extractant solvent, the residue was reconstituted in 100 μL deionized water and subsequently analyzed by CE-UV. Results: The developed method has remarkable characteristics, including simplicity, good repeatability and appreciable accuracy. Under the best extraction conditions, a low limit of detection at 7.0 μg per liter level with good linearity in the range of 0.02-10 μg mL^-1 was obtained. Conclusion: UA-DLLME, using a binary mixed extraction solvent, was established for the determination of tramadol in human plasma samples via the CE method with UV-detection. In addition, the analysis of tramadol in some plasma samples of patients with abuse of tramadol indicated that the method has acceptable performance for the determination of tramadol in plasma samples, which indicates that the method is suitable for clinical applications.