Solid phase extraction and determination of Fe (III) in some vegetables and natural water samples using a new inorganic/organic hybrid adsorbent

Abstract

A novel inorganic/organic hybrid material, silica-bound 3-((polyethyleneglycol)ethyl)-8-methyl-1H-imidazolium bromide (SiO₂- PEG-ImBr), was prepared and applied to extract and preconcentrate Fe (III) ions from complex matrices. The method is based on the adsorption and extraction of iron (III) after passing on inorganic/organic hybrid adsorbent in a column with detection by flame atomic absorption spectrometry (FAAS). The optimum conditions for adsorption were evaluated by changing various parameters such as initial pH of the solution, contact time, adsorbent dose, eluent kind and volume. Nitric acid 2 M as eluent was sufficient to obtain the recovery of >98% for Fe (III). The calibration curve was linear in the range of (6–200 ng mL⁻¹) with a correlation coefficient of 0.9991. The limit of detection based on three times the standard deviation of the blank was 1.93 ng mL⁻¹ when 100 mL sample volumes were used. The relative standard deviation (RSD) for determination of 30 ng mL⁻¹ of iron (III) was 3.9%. Langmuir isotherm was demonstrated to describe the adsorption data and the pseudo second-order kinetic model fits the adsorption kinetic processes well. The adsorption capacity of this inorganic/organic hybrid adsorbent has been found to be 4.37 mg g ⁻¹ of hybrid adsorbent. The method was successfully applied to the determination of iron (III) in some vegetables and water samples.

Keywords:

• adsorbent
• equilibrium
• Fe (III)
• kinetics
• preconcentration
• solid phase extraction