Lead‐Selective Potentiometric Sensor Based on Macrocyclic Ionophore [Pyo₂(16)Diene N₆]

Abstract

Polystyrene‐based membrane of 2,3,4:10,11,12‐dipyridine‐1,3,5,9,11,13‐hexaazacyclohexadeca‐2,10‐diene with sodium tetraphenyl borate (STB) and dibutyl phthalate (DBP) as anion excluder and plasticizing agent was prepared and investigated as Pb(II)‐selective electrode. The best performance was observed with the membrane having the polystyrene‐ligand‐DBP‐STB composition 1:6:1:1, worked well over a wide concentration range (1.41 × 10⁻⁶ to 1.00 × 10⁻¹ mol L⁻¹) with a Nernstian slope of 29.0 mV per decade of concentration between pH 3.0 and 6.0. The limit of detection is 1.0 × 10⁻⁶. This electrode has been found to be chemically inert and of adequate stability with a response time of 15 s and was used over a period of 100 d with good reproducibility (S = 0.3 mV). The membrane works satisfactorily in a partially nonaqueous medium up to a maximum 30% (v/v) content of methanol, ethanol, and acetone. The potentiometric selectivity coefficient values indicate that the membrane sensor is highly selective for Pb (II) ions over a number of monovalent, divalent, and trivalent cations. The practical ability of the membrane sensor has also been observed in solutions contaminated with detergents (i.e., cetyltrimethylammonium bromide and sodium dodecyl sulfate). The membrane electrode has also been successfully used to determine Pb²⁺ in real samples.

Supported by the Council of Scientific and Industrial Research (CSIR), New Delhi, India.

Keywords:

• Lead selective electrode
• macrocyclic ionophore
• potentiometric sensor

Notes

Supported by the Council of Scientific and Industrial Research (CSIR), New Delhi, India.