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 4 ). 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.