Ion Imprinted Polymer for Preconcentration and Determination of Ultra-Trace Cadmium,Employing Flow Injection Analysis with Thermo Spray Flame Furnace Atomic Absorption Spectrometry

This work proposes a preconcentration method using an ion imprinted polymer (IIP) for determination of cadmium, in several samples, employing a mini-column filled with the polymer coupled into a flow injection analysis system with detection by thermospray flame furnace atomic absorption spectrometry (FIA-TS-FF-AAS). The polymer was synthesized via bulk using methacrylic acid and vinylimidazole as a functional monomer. For the FIA system initial assessment, the variables: pH, eluent concentration and buffer concentration were studied, employing a 23 full factorial design. To obtain the optimum values for each significant variable, a Doehlert matrix was employed. After the optimization conditions as: pH 5.8, eluent (HNO3) concentration of 0.48 mol L⁻¹ and buffer concentration of 0.01 mol L⁻¹, were adopted. The proposed method showed a linear response in the range of 0.081–10.0 μg L⁻¹, limits detection and quantification of 0.024 and 0.081 μg L⁻¹, respectively; preconcentration factor of 165, consumptive index of 0.06 mL, concentration efficiency 132 min⁻¹, and frequency of readings equal to 26 readings h⁻¹. The accuracy was checked by analysis of certified reference materials for trace metals and recovery tests. The obtained results were in agreement with 95% confidence level (t-test). The method was adequate to apply in samples of: jewelry (earrings) (2.38 ± 0.28 μg kg⁻¹), black tea (1.09 ± 0.15 μg kg⁻¹), green tea (3.85 ± 0.13 μg kg⁻¹), cigarette tobacco (38.27 ± 0.22 μg kg⁻¹), and hair (0.35 ± 0.02 μg kg⁻¹).