Copper(II)-selective membrane electrodes based on o-xylylene bis(dithiocarbamates) as neutral carriers

Abstract

o-Xylylene bis(diisobutyl- and methyloctadecyl-dithiocarbamate) were synthesised and used as neutral carriers in membrane electrodes to improve the selectivity for Cu²⁺. The electrodes based on these ionophores, with o-nitrophenyl octyl ether as a plasticising solvent mediator and potassium tetrakis-(p-chlorophenyl)borate as an anion excluder, exhibit a linearity range of 10^–1–10^–6Mand have a Nernstian slope of 28–29 mV per decade at 25 °C. The highly selective electrode based on o-xylylene bis(diisobutyldithiocarbamate) rejected the interference of alkali, alkaline earth and transition metal cations by a factor in the range 10²–10⁴ and showed a high selectivity for Cu²⁺ even in chloride and bromide media. The properties of the electrodes are discussed and also compared with those of o-xylylene bis(diethyldithiocarbamate) under similar measurement conditions.