Potentiometric sensing of iodide using polymeric membranes of microwave stabilized β-AgI

A polymer based heterogeneous ion selective electrode (ISE) membrane was fabricated for the potentiometric sensing of iodide. The sensing element used for the preparation of the ISE membrane was microwave stabilized β-AgI. Because microwave energy was found to be beneficial for causing hysteresis at the phase transition temperature of AgI, an attempt has been made to prepare stable and conductive β-AgI crystals by post microwave irradiation under high pressure. A conventionally precipitated AgI based ISE was also fabricated for comparative studies. The β-AgI based ISE could respond to a wide range of iodide concentrations (1 × 10−8 to 1 M) within 60 s with a detection limit of 10 nM. The ISE gave stable response to iodide ions in a pH range of 2.0–8.0 and was highly selective in the presence of various interfering ions. The performance of the proposed iodide ISE in the analysis of natural and seawater samples was encouraging, and the determination of iodide in table salt and human urine samples was explained using the developed sensor.

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► Stable β-phase was obtained by post MW irradiation of AgI precipitate.
► Constructed ISEby dispersing stable β-AgI crystals in polyvinyl chloride.
► Designed iodide ISE exhibited wide linear range and fast response.
► Highly selective with selectivity factors less than 10−6.
► Successfully applied to natural waters, table salt and human urine samples.