Hydrotalcite-like compounds as ionophores for the development of anion potentiometric sensors

A double layered hydroxide anionic clay containing chloride or nitrate as t he interlayer anion has been used to prepare ion-selective electrodes (ISE) for potentiometric sensing of the intercalated anionic species. The electr odes exhibited a linear range for the potential response to logarithm of co ncentration: from 5.0 x 10(-5) to 2.0 x 10(-1) M with an average slope equa l to - 54.2 mV decade(-1) for chloride and from 2.0 x 10(-4) to 1.0 M with an average slope equal to - 48.3 mV decade-1 for nitrate. The response time was from 1 to 6 min, depending on the analyte concentration; the stability of the signal was quite satisfactory. The effect of interfering ions has b een investigated and the values of the relevant selectivity constants have been determined. The lifetime of the sensors was at least 2 weeks. (C) 2000 Elsevier Science B.V. All rights reserved.