Selective solid-phase extraction of trace Fe(III) from biological and natural water samples using nanometer SiO2 modified with acetylsalicylic acid

. A new method using acetylsalicylic acid (aspirin) modified SiO 2 nanoparticles (nanometer SiO 2 -aspirin) as a solid-phase extractant (SPE) has been developed for the preconcentration of trace amounts of Fe(III) prior to their determination by inductively coupled plasma optical emission spectrometry. The preconcentration conditions of analytes were investigated, including the pH value, the shaking time, the mass of sorbent, the sample flow rate and volume, the elution condition and the interfering ions. At pH 4, the sorption capacity of nanometer SiO 2 -aspirin was found to be 1.28 mmol g −1 . The preconcentration factor is 50. The detection limit (3σ) for Fe(III) was 0.49 ng mL −1 . The method was validated by analyzing two certified reference materials (GBW 08301, river sediment and GBW 08303, polluted farming soil), and the results obtained are in good agreement with standard values. The method was also applied to the determination of trace Fe(III) in biological and water samples with satisfactory results.