Analysis of alendronate in human urine and plasma by magnetic solid-phase extraction and capillary electrophoresis with fluorescence detection

A simple, rapid and sensitive CE-fluorescence (FL) detection method for the analysis of alendronate (ALEN), a bisphosphonate drug, has been developed. Using a buffer solution of 20 mM sodium phosphate (pH 10.0) and a voltage of 24 kV, separation of ALEN in a 55-cm length (35-cm effective length) capillary was achieved in 5 min. FL detection of ALEN was performed via pre-column derivatization with 2,3-naphthalene dicarbox-yaldehyde (NDA). Linear correlation (r=0.9981, n=6) between FL intensity and analyte concentration was obtained in the range of 7200 ng/mL ALEN. The developed CE-FL method was applied to the analysis of ALEN in human urine and plasma samples. In order to eliminate the interfering matrix components, SPE using magnetic Fe3O4@Al2O3 nanoparticles as solid sorbents was employed to clean the biological fluids before CE-FL analysis. The linear ranges of ALEN in urine and plasma were 5100 ng/mL (r = 0.9982, n = 7) and 570 ng/mL (r = 0.9954, n = 7), respectively. The LOD and LOQ in both urine and plasma samples were 1.5 and 5 ng/mL ALEN, respectively. Total analysis time including sample pre-treatment and CE separation was less than 1.5 h.