Separation-preconcentration and ultra trace lead determination in the environmental sample by a combination of ion-imprinted polymer and solidification of floating organic drop microextraction

Abstract

ABSTRACT The ion-imprinted polymer combined with the solidification of floating organic drop microextraction has been developed as an ultra-pre-concentration technique to determine lead ions in real samples. In ion-imprinted polymer – solidification of floating organic drop microextraction, lead was adsorbed from a large volume of aqueous samples (500 mL) into 100 mg of the ion-imprinted polymer sorbent. After the elution of lead ions from the sorbent by using nitric acid, the solidification of floating organic drop microextraction technique was performed on the obtained solution. Several important extraction parameters, such as weight of ion-imprinted polymer (mg), pH, uptake time (min), desorption time (min), HNO3 desorption volume (mL) aqueous-phase volume (mL), were studied and optimised. The ion–imprinted polymer particles were characterised by Fourier transform infrared spectroscopy and scanning electron microscopy (SEM). The new method (SPE–SFODME) provided an ultra-enrichment factor (5000) for lead. The calibration graphs were linear in the range of 5–200 ng L−1. The optimum conditions for the method were as follows: pH of solution, 7.5; weight of ion-imprinted polymer, 100 mg; type and concentration of eluent, HNO3 1 M; volume of eluent, 1 mL; sorption time, 25 min; desorption time, 15 min. Under optimum conditions, the limit of detection (LOD) was 1 ng L−1 for lead and relative standard deviation (RSD %) for five replicate determinations of 10 ng L−1 for lead was 6.5%. The results for the determination of lead ions in reference materials, tap water, ground vegetables, butter and flour wheat demonstrated the accuracy, recovery and applicability of the presented method.