Double-imprinted polymer based on cross-linked poly(vinylimidazole-trimethylolpropane trimethacrylate) in solid phase extraction for determination of lead from wastewater samples by UV-vis spectrophotometry

The monitoring of the heavy metal pollution in wastewater is increasingly becoming a crucial global issue since they tend to accumulate in food chains and can cause many biological abnormalities. In this work, it was developed a novel lead ion-imprinted polymer (IIP) using sodium dodecyl sulphate (SDS) as a second template to be used as adsorbent in solid phase extraction (SPE) for determination of lead from wastewater samples by UV-vis spectrophotometry. The polymer called IIP-SDS was synthesised by a double-imprinting process with lead (template) and SDS (template). IIP-SDS was characterised by infrared spectroscopy Fourier transform infrared spectroscopy, thermogravimetric analysis and scanning electron microscopy. IIP-SDS showed good recovery for lead (around 82.0%), while the IIP (only lead as template) was 72.2% and non-IIP was 44.9%. Thus, the double-imprinting process for the preconcentration of Pb2+ proved to be a more adequate methodology than IIP with a single template. The optimised parameters of sample preparation were washing solvent (2.0 mL of tetrahydrofuran), type and volume of eluent (5 mL of 1 mol L-1 hydrochloric acid), sample amount (30 mL of water spiked with 10.0 mu g mL(-1)), amount of IIP-SDS (400 mg) and sample pH (pH = 4.5). Linearity ranged from 10 to 125 mu g L-1 with r > 0.992. The limit of detection and quantification were 6.3 and 10 mu g L-1, respectively. The precision (relative standard deviation, %) and accuracy (relative error, %) were lower than 15%. Finally, IIP-SDS may be an alternative and effective adsorbent for SPE procedures in monitoring of wastewater samples.