Online Preconcentration System Using 6-(2-Thienyl)-2-Pyridine Carboxaldehyde Functionalized Amberlite XAD-4 Resin for the Determination of Trace Elements in Waters by Flame Atomic Absorption Spectrometry

An online flow injection method was developed for the determination of trace elements in waters using 6-(2-thienyl)-2-pyridinecarboxaldehyde functionalized Amberlite XAD-4 resin. The metals were eluted with 1.0 M HNO3 directly to a flame atomic absorption spectrometry determination system. The sorption capacities of the resin for metal ions were 74.6, 113.7, 48.3, 131.6, and 88.6 μmol/g for Cd(II), Ni(II), Pb(II), Co(II), and Cu(II), respectively. The resin was found to be very stable and capable of being used for more than 250 retention and elution cycles without major loss of performance. Detection limits (3SD) were determined to be 0.14 μg/L for Cd, 0.39 μg/L for Cu, 0.82 μg/L for Ni, 0.88 μg/L for Co, and 2.54 μg/L for Pb using 10 mL sample loading. The accuracy of the proposed method was checked using different certified reference materials [estuarine water (SLEW-3), riverine water (SRLS-5), 19-element aqueous standard (QCS-19), wheat flour (NBS 1567 a), and rice flour unpolished high level Cd (NIES 10c)]. Results were in agreement with certified values. The proposed method was applied to the determination of Cu, Ni, Co, Cd, and Pb in natural water samples. The recovery values for spiked water samples were between 91.9 and 107.4%.