On-line micro-solid phase preconcentration of Cd2 + coupled to TS-FF-AAS using a novel ion-selective bifunctional hybrid imprinted adsorbent

Abstract

A novel hybrid ion imprinted polymer (HIIP) is proposed aiming at the development of an online micro-solid phase preconcentration system of Cd2+ coupled to TS-FF-AAS. To evaluate the selective and adsorptive performance of HIIP towards Cd2+, hybrid non-imprinted polymer (HNIP), organic ion imprinted polymer (OIIP), and the inorganic ion imprinted polymer (IIIP) were synthesized and compared with each other. Adsorption capacity of HIIP was 53% higher than HNIP, and dual-site Langmuir–Freundlich isotherm model showed the best fit for data of both polymers. The preconcentration system coupled to TS-FF-AAS was performed by loading 10.0mL of Cd2+ solution at pH7.5 through 80.0mg of HIIP packed into a micro-column with posterior online elution using 1.0molL−1 HCl/ethanol 1:1 (v/v) mixture. The developed method was highly tolerant for other metal ions Zn2+, Pb2+, Cu2+, Co2+, Fe2+, and Hg2+ at analyte:interferent (1:50, m/m) ratio and Ca2+ and Mg2+ at 1:500 (m/m) ratio. Analytical curve ranging from 0.5 to 7.0μgL−1, limit of detection of 30ngL−1 and preconcentration factor of 14-fold were obtained. Intra-day and inter-day (3days) experiment precision (n=10) was, respectively, 3.9 and 0.6% (relative standard deviation, RSD), and 4.4 and 2.4% for concentrations of 0.7 and 6.5μgL−1. Sensitivity of method (Abs Lμg−1) was about 3.3, 2.2 and 1.9-fold higher when compared to preconcentration method using HNIP, OIIP and IIIP, respectively, thus clearly showing that hybrid polymer and imprinting process enhance Cd2+ adsorption. Addition and recovery experiments ranging from 94 to 106% in mineral, lake water and tap water, urine and cigarette samples attested the feasibility of method for analysis of matrices containing different components. Moreover, the accuracy of method was checked from analysis of certified reference material (DOLT-4, fish liver), being the obtained value of 23.9±0.6mgkg−1 (n=3) statistically equal to the certified value of 24.3±0.8mgkg−1, by applying Student t-test at 95% confidence level.