The values for the equilibrium constants (K2, K3) were estimated from the relevant Eo values. The simulated voltam-

o-Xylylene bis(diisobuty1-and methyloctadecyl-dithiocarbamate) were synthesised and used as neutral carriers in membrane electrodes t o improve the selectivity for Cu2+. The electrodes based o n these ionophores, with o-nitrophenyl octyl ether as a plasticising solvent mediator and potassium tetrakis-(p-chloropheny1)borate as an anion excluder, exhibit a linearity range of 10-1-10-6 M and have a Nernstian slope of 28-29 mV per decade at 25°C. The highly selective electrode based o n o-xylylene bis(diisobuty1dithiocarbamate) rejected the interference of alkali, alkaline earth and transition metal cations by a factor in the range l O 2 -l O 4 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(diethy1dithiocarbamate) under similar measurement conditions.

PVC membrane electrodes that are selective and sensitive to copper(l1) have been developed. The best electrode, based on 13,14-benzo-I ,5-tetrathiacyclopentadecane and 2-nitrophenyl octyl ether solvent mediator w i t h a potassium tetrakis(p-chloropheny1)borate anion excluder, exhibits a linear response in the range 10-1-10-6 M over the pH range 2.9-6.7 and has a Nernstian slope of 28-29 m V per decade at 25 "C. The response time is 10 s.

Poly(vinyl chloride) membrane electrodes that are sensitive and selective to copper(II) ion were developed. The electrodes based on tetramethyl, tetraethyl and dipyrrolidine thiuram monosulfides as a neutral carrier, exhibit a Nernstian behavior to copper(II) ion in the activity range of 10−1 M to 10−6 M–10−8 M. Properties of the electrodes are briefly discussed.

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