Properties of naproxen ion-selective electrodes

Naproxen membrane electrodes based on different plasticizers and the quaternary ammonium salts (QASs) dimethyldidecylammonium bromide, methyltrioctylammonium chloride, or tetraoctylammonium chloride, were prepared. The following basic parameters were investigated for the optimal electrode: measurement range (10−4 − 10−1 mol L−1), slope of the linear range of the calibration curve (−58.3 mV decade−1), limit of detection (6.0 × 10−5 mol L−1), lifetime (2.5 months), dependence of the electrode potential on pH (5.5 − 9.0), reproducibility of potential (1.2 mV) and selectivity coefficients in relation to selected organic and inorganic anions. The electrode was utilized for determination of naproxen in tablets by the calibration curve method and the standard addition method.

Coupled transport of cyanide ions through liquid membranes

In this study, the transport kinetics of coupled transport of cyanide ions through liquid membrane (trichloromethane) containing tetraoctylammonium chloride as a carrier was examined at different temperatures. The kinetics of cyanide transport could be analyzed in the formalism of two consecutive irreversible first order reactions. The influence of the temperature on the kinetic parameters (k1d, k2m, k2a, Rmmax, tmax, Jdmax, Jamax) has been established. For maximum membrane entrance and exit fluxes, Jdmax and Jamax, the activation energies were found from the slopes of the two linear relationships: 9.02 kcal/mol and 11.20 kcal/mol, respectively. The values of the found activation energy indicate that in the first step the transport process of cyanide ions through liquid membrane is difussional controlled, whereas in the second step it is most probably controlled by species diffusion and the rate of the reversible chemical reaction.