Design of a ruthenium(III) immobilized affinity material based on a β-cyclodextrin-functionalized poly(glycidyl methacrylate-ethylene dimethacrylate) monolith for the enrichment of hippuric acid.

Immobilized metal affinity chromatography has drawn great attention as a widespread separation and purification approach. In this work, ruthenium was firstly introduced into the preparation of immobilized metal affinity chromatography considering its affinity to N,O-donor ligands. A β-cyclodextrin-functionalized poly(glycidyl methacrylate-ethylene dimethacrylate) monolith was designed and employed as the supporting material in immobilized metal affinity chromatography. Thiosemicarbazide was introduced into the synthesis process, which not only acted as a bridge between β-cyclodextrin and glycidyl methacrylate, but also chelated with ruthenium because of its mixed hard-soft donor characteristics. The developed monolithic ruthenium(III)-immobilized metal affinity chromatography column was utilized for the adsorption and separation of hippuric acid, a biological indicator of toluene exposure. To achieve high extraction capacity, the parameters affecting the extraction efficiency were investigated with an orthogonal experiment design, L9 (3 ). Under the optimized conditions, the enrichment factor of hippuric acid was 16.7-fold. The method reproducibility was investigated in terms of intra- and interday precisions with relative standard deviations lower than 8.7 and 9.5%, respectively. In addition, ruthenium(III)-immobilized metal affinity chromatography material could be used for up to 80 extractions without an apparent change in extraction recovery.