The use of a bromide ion selective electrode for the measurement of counter-ion activity in cationic surfactant solutions.

Abstract

Abstract A bromide ion selective electrode has been used in conjunction with a saturated calomel reference electrode to measure bromide ion activity in solutions of n-decyl, n-dodecyl, n-tetradecyl and n-hexadecyl 1-trimethylammonium bromides at 30°; the critical micelle concentrations of the surfactants were measured by electrical conductance. Calibration of the electrode pair in potassium bromide solutions produced a linear response over the range 0·5 to 5·0p Bra− with a slope of 59·1 mV for a 10-fold change in activity. Results for the surfactants were treated to give values for the degree of micellar dissociation; literature values for this quantity reveal wide variation depending on the technique used.