Analytical Sciences

Abstract − Analytical Sciences, 36(7), 847 (2020).

Roles of Residual Silanol in Solid Phase Extraction of Copper to Octadecylsilyl Silica in the Presence of Acetylacetone
Shizuka NASU, Satoshi OHMURO, Takashi YASUI, and Akio YUCHI
Graduate School of Engineering, Nagoya Institute of Technology, Gokiso, Showa, Nagoya 466-8555, Japan
Batchwise studies have demonstrated that the retention of acetylacetone (Haa) from an aqueous phase in non-endcapped octadecylsilyl (ODS) silica with silanol intentionally left (NEC) is stronger than the retention in endcapped ODS silica under ambient pressure, due to the enhanced wettability and the contribution of adsorption to silanol (–SiOH) as well as of the distribution into the ODS phase. Equilibrium analysis on solid phase extraction (SPE) of copper ion with Haa to NEC has indicated the adsorption of 1:1 species by the proton replacement reaction with silanol to give [–SiOCu(aa)] at relatively low Haa concentrations and the adsorption of [Cu(aa)2] to silanol, as well as the distribution of [Cu(aa)2] into the ODS phase. These adsorbed and distributed species of the same composition could be differentiated by ESR spectroscopy. The advantages of residual silanol in SPE of metal ions are discussed.