title: Potentiometric evaluation of calix[4]arene anion receptors in membrane electrodes: phosphate detection.
abstract: Ion-selective membrane electrodes doped with the urea- or thiourea-functionalised calix[4]arenes, 5,11,17,23-tetra-tert-butyl-25,27-bis[[4-N'-(phenylureido)butyl]oxy]-26,28-dipropoxy calix[4]arene (I) and 5,11,17,23-tetra-tert-butyl-25,27-bis[[4-(N'-phenylthioureido)-butyl]oxy]-26,28-dipropoxy calix[4]arene (II), were evaluated for anion sensing. Potentiometric results show that these calixarene ionophore-based membrane electrodes exhibit a good sensitivity to aqueous solutions of the monohydrogen orthophosphate species HPO(4)(2-) in the concentration range 5.0 x 10(-5) to 1.0 x 10(-1)M, with near-Nernstian response slopes of -33.0 and -28.0 mV dec(-1) for ionophores I and II, respectively. Selectivity coefficient values for monohydrogen orthophosphate over a range of common anions were determined by the fixed interference and matched potential methods and indicated that these membrane electrodes exhibit a good selectivity for HPO(4)(2-) with respect to the other anions, including sulfate and nitrate.
authors: Tyndall National Institute, Lee Maltings, University College, Cork, Ireland.
authors: Francine
authors: F
authors: Kivlehan
authors: Wade J
authors: WJ
authors: Mace
authors: Humphrey A
authors: HA
authors: Moynihan
authors: Damien W M
authors: DW
authors: Arrigan
mesh_terms: D000838:Anions; D047250:Calixarenes / Q000737:chemistry*; D004305:Dose-Response Relationship, Drug; D004563:Electrochemistry / Q000379:methods; D004566:Electrodes; D017736:Ion-Selective Electrodes; D007477:Ions; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D009566:Nitrates / Q000737:chemistry; D010636:Phenols / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry*; D011199:Potentiometry / Q000379:methods*; D012680:Sensitivity and Specificity; D017550:Spectroscopy, Fourier Transform Infrared; D013431:Sulfates / Q000737:chemistry
chemical_list: D000838:Anions; D007477:Ions; D009566:Nitrates; D010636:Phenols; D010710:Phosphates; D013431:Sulfates; C121325:calix(4)arene; D047250:Calixarenes