Thiol functionalised ionic liquid based xerogel: a novel and efficient support for the solid phase extraction of transition metal ions

Abstract

In the present study, a novel thiol functionalised ionic liquid based xerogel (XeIL-SH) has been synthesised and used for the solid phase extraction of Fe³⁺, Co²⁺, Cu²⁺, Ni²⁺, Pb²⁺, and Zn²⁺ ion. The XeIL-SH was prepared by hydrolysis and condensation of 1,3-bis(3-trimethoxysilylpropyl)-imidazolium iodide (BTMSPI) followed by grafting of 3-thiopropyl trimethoxysilane under argon atmosphere. The morphology and approximate particle sizes of the material were determined by scanning electron microscopy. The presence of organic functional groups in the silica framework was also characterised by diffuse reflectance infrared spectroscopy. After characterisation, the XeIL-SH was successfully applied for the solid phase extraction of Fe³⁺, Co²⁺, Cu²⁺, Ni²⁺, Pb²⁺, and Zn²⁺ ion. The influence of effective parameters such as sample flow rate, pH, eluent conditions (type, volume, and concentration) and matrices effect on metal ion recoveries were studied and optimised. The results showed that the limits of detection (LODs) are in the range of 1.5–2.8 µg L⁻¹ and preconcentration factor is about 150. The procedure was also effectively applied for the determination of analytes in various real samples with recoveries > 94.8% and R.S.D. less than 4.4% (N = 5).

Keywords:

• ionic liquid
• solid phase extraction
• thiol functional group
• transition metal ions
• xerogel