Determination of rhodium by resonance light-scattering technique coupled with solid phase extraction using Rh(III)
Bing Yang1, Ting Zhang, Wenxiang Tan
1School of Chemical Science and Technology, Key Laboratory of Medicinal Chemistry for Nature Resource, Ministry of Education, Yunnan University, Kunming 650091, China.
Abstract:
A resonance light-scattering method (RLS) for the determination of Rh(III) was initially developed, based on the reaction among Rh(III), WO4(2-) and ethylrhodamine B. The method possesses high sensitivity, but lacks selectivity. Therefore, a Rh(III) ion-imprinted polymer (IIP), prepared by precipitation polymerization using 2-(allylthio)nicotinic acid (ANA) as functional monomer, was used as sorbent to construct a ion-imprint based solid-phase extraction (IIP-SPE) method for separation of rhodium from complicated matrices prior to its determination by RLS. The experimental parameters affecting the extraction efficiency and selectivity of IIP-SPE were studied carefully. Under the optimal conditions, the IIP-SPE column with the enrichment factor (EF) of 10 could be used at least 20 times without decreasing its extraction recovery (above 90%) significantly. The calibration graph for the determination of rhodium by RLS coupled with IIP-SPE procedure was linear in the range of 0.06-1.5 ng mL(-1) with the detection limit of 0.024 ng mL(-1). There is no metal ions tested at the concentration below 10 ng mL(-1) interfered in the determination of 0.8 ng mL(-1) Rh(III). The proposed IIP-SPE-RLS method was successfully applied to the extraction and measurement of trace rhodium in catalyst, water and geochemical samples with the relative standard deviation (RSD) of less than 4.0% (n=4).
