Quantitative analysis of cyclosporine A in whole blood samples of liver transplant recipients using a stir bar-assisted magnetic dispersive solid phase extraction combined with HPLC-MS/MS.

Cyclosporine A is an immunosuppressive drug which is used in the organ transplantation and treatment of autoimmune diseases. Also, it has been approved to be used as a hepatoprotective agent in the liver transplant recipients. Nephrotoxicity is the major toxic side effect of cyclosporine and due to its narrow therapeutic index, the doses must be adjusted individually. In the current research, a stir bar-assisted magnetic dispersive solid phase extraction method followed by high performance liquid chromatography-tandem mass spectrometry has been introduced and validated for the quantitative analysis of cyclosporine A in the whole blood samples of liver transplant recipients. In this method, briefly, 15 mg of synthesized Fe3O4@bio-metal-organic framework@molecularly imprinted polymer is added into the sample solution and then started to disperse using a stir bar. After that, the sorbent particles containing the adsorbed analyte are collected onto the bar. In the following, the stir bar is transferred into another vial containing the elution solvent and the stirring process is started again to elute the analyte. Then, the liquid phase is taken and evaporated. Finally, the residue is dissolved in the mobile phase and analyzed by using high performance liquid chromatography-tandem mass spectrometry. Amount of the sorbent, stirring rate and time in adsorption step, ionic strength and pH of sample solution, type and volume of elution solvent, and stirring rate and time in desorption step, are the key parameters that optimized in this work. Under the optimum conditions, low limits of detection (0.20 ng mL-1) and quantification (0.69 ng mL-1), good extraction recovery (80%), broad linear range (0.69-500 ng mL-1), and good precisions (relative standard deviation ≤ 6.2%) were obtained using the proposed method. Finally, the applicability of the method was evaluated by analyzing the blood samples obtained from liver transplant recipients. Considering the outcomes, the concentrations of cyclosporine A in the mentioned samples were in the range of 140.5-196.9 ng mL-1.