Ultrasound assisted-dispersive-micro-solid phase extraction based on bulky amino bimodal mesoporous silica nanoparticles for speciation of trace manganese (II)/(VII) ions in water samples

This report described the use of amine-functionalized mesoporous silica UVM-7 as nanoadsorbent in ultrasound assisted-dispersive-micro-solid phase extraction (US-D-mu-SPE) procedure for rapid speciation/preconcentration of trace amounts of manganese (II) and manganese (VII) ions, from water samples prior to their determination by atom trapping-flame atomic absorption spectrometry (AT-F AAS). All main factors for the quantitative recoveries of Mn(II)/Mn(VII) ions were investigated and optimized. Based on the developed method, preconcentration and speciation of Mn(II) and Mn(VII) ions with NH2-UVM-7 were obtained in water samples due to the formation of NH-Mn2+ and -NH3+-MnO4- at optimum pH of 8 and 5, respectively. The batch adsorption capacity of NH2-UVM-7 for Mn(II) and Mn(VII) ions was found to be 1733 mu mol g(-1) and 570 mu mol g(-1), respectively. Under the optimized conditions, limits of detection (3S(b)/m), and limits of quantification (10S(b)/m) were 0.007 mu g L-1 and 0.03 mu g L-1 for Mn(II) as well as 0.008 mu g L-1 and 0.04 mu g L-1 for Mn(VII). The preconcentration factors for Mn(II) and Mn(VII) were calculated as 102.3 and 98.8, and their relative standard deviations were 2.3 and 2.8%, respectively (n = 10, C = 10 mu g L-1). The developed method was successfully applied to natural water samples. The validation of the method was also performed by the standard reference material. (C) 2015 Elsevier B.V. All rights reserved.