Sol-gel processed pyridinium ionic liquid-modified silica as a new sorbent for separation and quantification of iron in water samples

1-Hexylpyridinium hexafluorophosphate [C6py][PF6] ionic liquid (IL) was firstly used for chemical modification of silica utilizing the acid-catalyzed sol-gel processing. The obtained pyridinium IL-modified silica was employed as a solid phase extraction (SPE) sorbent for removal of trace levels of Fe(III) ions from aqueous samples. The influence of different variables on the separation efficiency, including the concentration of chelating agent, pH, sample flow rate and volume, eluent type, concentration and volume, and interfering ions was investigated by flame atomic absorption spectrometry (FAAS). In the optimum experimental conditions, the limit of detection (3s), limit of quantification (LOQ) and pre-concentration factor were 0.7 μg L−1, 2.5 μg L−1, and 200, respectively. The relative standard deviation (RSD) for nine replicate determinations of 25 μg L−1 Fe was 3.2%. The calibration graph using the pre-concentration system was linear in the range of 2.5-50 μg L−1 with a correlation coefficient of 0.9997. The developed method was validated by the analysis of certified reference material and applied successfully to the separation and determination of iron in several water samples.