Potentiometric Responses of Polymeric Liquid Membranes Based on Hydrophobic Chelating Agents to Metal Ions

Yasoo Itoh, Yoshihisa Ueda, Ayumi Hirano, Masao Sugawara, Koji Tohda, Hideo Akaiwa, Yoshio Umezawa

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


The effect of hydrophobicity of acidic chelating agents as sensing materials on the potentiometric responses of polymeric liquid membranes was investigated. The chelating agents tested were 8-quinolinol (HOx), dithizone (HDz), 1-(2-pyridylazo)-2-naphthol (PAN) and their alkylated analogues, 5-octyloxymethyl-8-quinolinol (HO8Q), di(p-hexylphenyl)thiocarbazone (C6HDz), 7-pentadecyloxy-1-(2-pyridylazo)-2-naphthol (C15PAN) and a series of N-alkylcarbonyl-N-phenylhydroxylamines (CnPHA, n = 3, 6, 9, 12). The distribution coefficients between membrane solvent and water were determined to evaluate the hydrophobicity of the agents. The potential-pH profiles of the membranes containing hydrophobic chelating agents demonstrated the generation of potentiometric responses, while less hydrophobic agents gave no response. A possible model for the generation of membrane potential is proposed. The charge separation is attained by the permselective uptake of metal cations by the chelating agent anion at membrane/solution interface, where the high hydrophobicity of the agent enables the anionic or deprotonated form of the agents to remain at the membrane/solution interface.

Original languageEnglish
Pages (from-to)621-627
Number of pages7
JournalAnalytical Sciences
Issue number5
Publication statusPublished - 2001


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