Lithium-selective potentiometric sensor based on a second generation carbosiloxane dendrimer

A second generation triethylene glycolmonomethylether end-grafted carbosiloxane dendrimer (III) has been synthesized by the reaction of Si(OCH2CH2CH2SiMe(OCH2CH2CH2SiMe2Cl)2)4 (I) with triethylene glycolmonomethylether (II). PVC-based membranes of dendrimer III as electroactive material with sodium tetraphenylborate (NaTPB) as anion excluder and with plasticising solvent mediators have been prepared and used for Li (I) ion determination. The membrane having a composition of PVC:III:NaTPB:chloronaphthalene (150:21.5:3:150) exhibited the best result with linear potential response in the concentration range of 2.5 × 10−5 to 1.0 × 10−1 M of Li+ with a slope of 52.0 mV per decade of Li+ activity. The membrane can be used over a period of 2 months in aqueous as well as in non-aqueous medium with good reproducibility. The electrode works excellent in the pH range of 3.7-8.0. The selectivity coefficient values for mono-, bi-, and tri-valent cations indicate good selectivity for Li+ over a large number of cations.