Ionic liquid-modified silica as sorbent for preconcentration of cadmium prior to its determination by flame atomic absorption spectrometry in water samples.

A new method based on a microcolumn packed with ionic liquid-modified silica combined with flame atomic absorption spectrometry has been developed for the determination of trace amount of cadmium (Cd) in environmental samples. The ionic liquid-modified silica sorbent was prepared by the surface of commercial silica was chemically modified with ionic liquid. Several factors influencing the preconcentration efficiency of Cd and its subsequent determination, such as pH of the sample, sample flow rate and volume, concentration of chelating agent, eluent and interfering effect, have been investigated. Cd could be quantitatively retained by ionic liquid-modified silica in the pH range of 9-12, then eluted completely with 2.0 mL of 1.0 mol L(-1) HCl. The detection limit of this method for Cd was 0.60 microg L(-1) with an enrichment factor of 75, and the relative standard deviation (RSD) was 3.7% at the 100 microg L(-1) Cd level. The method has been applied for the determination of trace amount of Cd in water samples with satisfactory results.