Analytical Sciences

Pyrazole-Containing Crown Ethers as Ionophores for NH ₄⁺ -SelectiveElectrodes

Takayo MORIUCHI-KAWAKAMI,Shigeto NAKAZAWA, MitsuhikoOTA, Masanori NISHIHIRA, Hiroyuki HAYASHI, Yasuhiko SHIBUTANIand Toshiyuki SHONO

Department of Applied Chemistry,Faculty of Engineering, Osaka Institute of Technology, Omiya, Asahi, Osaka535-8585, Japan

The pyrazole-containing 18-membered crown ether1, which possesses a less-bulky substituent on thesp³ nitrogens and not only the sp²nitrogen, but also the carbonyl groups as ligating points, exhibitedexcellent ability as an ionophore for aNH₄⁺-selective electrode. The value of theselectivity coefficient of an ion-selective electrode (ISE) containing1for the NH₄⁺ ion with respect to aninterfering K⁺ ion was 6.3X10^-2. This result issuperior to that of ISE based on an antibiotic substance, nonactin(1.2X10^-1). (Keywords: Pyrazole unit, NH₄⁺-selectivity,ion-selective electrode)

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