Development of efficient pretreatment method for analyzing polar compound using solid-phase derivatization

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Two types of solid phases were examined for solid-phase derivatization of phenols with pentafluoropyridine.(1) Strong anion-exchange solid phaseAdsorption of phenols was performed by passing an alkaline solution through two strong anion-exchange solid phases, silica-based solid and polymer-based solid (Waters, OASIS MAX). Since the silica-based solid phase was labile to the alkaline solution, phenolate ions were not entirely adsorbed onto the solid phase. On the other hand, polymer based solid phase adsorbed effectively the phenolate ions. Quantitative derivatization was attained by retaining hexane solution of pentafluoropyridine to the cartridge for 10 minutes. We found that hydrophobic interaction as well as ionic interaction plays an important role for the adsorption.To evaluate the effect of matrix, the solid-phase derivatization was carried out in the presence of neutral and anionic compounds. As a result, derivatization reaction was not influenced at all. The neutral compounds w … More ere removed by passing acetone through the cartridge and anionic compounds (carboxylic acid) remained unreacted in the cartridge. Only the phenols derivatized with pentafluoropyridine were eluted with hexane solution of pentafluoropyridine.The limit of detection of this method (LOD : 0.88-8.5 ng/l in 100 ml sample) is much better than that of biphasic system using phase-transfer reagent (LOD : 6.9-85 ng/l in 50 ml sample, J.Chromatography A 984 (2003) 237-243), indicating the high performance of this method. Recovery from river water sample was satisfactory level. The method was successfully applied to the environmental water.(2) Ion-pair solid-phase extraction using C_<18>C_<18> solid phase on which THA (tetrahexylammonium bromide) was adsorbed, gave the similar results to OASIS MAX described above. In this case, pheolate ions that were effectively adsorbed onto C_<18> solid phase + THA, were eluted and derivatized with acetone solution of pentafluoropyridine. No reaction time was required for this ion-pair SPE. Less