Highly selective determination of rhodium(III) using silica gel surface-imprinted solid-phase extraction

Abstract

A novel Rh(III)-imprinted amino-functionalised silica gel sorbent was prepared by a surface imprinting technique for preconcentration and separation of Rh(III) prior to its determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). Compared with the traditional solid sorbents and non-imprinted polymer particles, the ion-imprinted polymers (IIPs) had higher adsorption capacity and selectivity for Rh(III). The maximum static adsorption capacity of the imprinted and non-imprinted sorbent for Rh(III) was 29.86 mg g⁻¹ and 11.23 mg g⁻¹, respectively. The imprinted Rh(III) was removed with 2 mL of 3% thiourea + 2 mol L⁻¹ HCl. The obtained imprinted particles exhibited excellent selectivity and rapid kinetics process for Rh(III). The relatively selective factor (α_r) values of Rh(III)/Ru(III), Rh(III)/Au(III), Rh(III)/Pt(IV), Rh(III)/Ir(IV), Rh(III)/Pd(II) were 26.7, 39.0 29.2, 28.1, 43.7, respectively, which were greater than 1. The detection limit (3σ) of the method was 0.26 µg L⁻¹. The relative standard deviation of the method was 1.79% for eight replicate determination of 10 µg of Rh³⁺ in 200 mL water sample. The method was validated by analysing standard reference material (GBW 07293), the results obtained is in good agreement with standard values. The developed method was also successfully applied to the determination of trace rhodium(III) in geological samples with satisfactory results.

Keywords:

• Rh(III)
• solid-phase extraction
• surface imprinting silica gel
• preconcentration
• ICP-AES

Acknowledgements

The authors are thankful for financial support from the Key Project of Chinese Ministry of Education (No. 208155) and QingHai Science and Technology Department (No. 2008-G-166).