LAUSR

Abstract The present paper describes a new restricted access material-ion imprinted polymer for on-line preconcentration of Cd2+ from natural water samples, and simultaneous clean-up of humic acid. Cadmium-imprinted poly(allylthiourea) was synthesized and modified with 2-hydroxyethyl methacrylate (IIP-HEMA) to obtain the restricted access ability. The on-line flow injection system coupled to FAAS (FIA-FAAS) was based on percolation of 20.0 mL of the sample (pH 8.70 and in presence of organic matter) through a mini-column (100.0 mg of IIP-HEMA) at 7.5 mL min−1 flow rate. The elution step was performed using 2.0 mol L−1 HNO3 at 5.0 mL min−1 flow rate. The method provided linearity in the range 0.56–50.00 μg L−1 and limit of detection of 0.17 μg L−1. The preconcentration factor was found to be 37-fold, consumption index of 0.54 mL, preconcentration efficiency of 13.10 min−1 and sample throughput of 21 h−1. The precision of the method was evaluated in terms of intra-day and inter-day repeatability and the relative standard deviation percentage (%RSD) obtained by two-level concentration (2.50 and 40.00 μg L−1) in the presence and absence of humic acid were