SELF-ASSEMBLED LIPID BILAYERS AS A POTASSIUM SENSOR

The effect of valinomycin on a novel bilayer lipid membrane (BLM) syst em supported on a metallic wire (s-BLM) has been investigated. An incr ease in concentration of valinomycin from 6 X 10(-6) to 6 X 10(-4) mol L-1 increases the conductivity of the system after addition of potass ium ions. A remarkable effect of the buffer medium on the electrode re sponse has been observed, a solution of 0.1 M Tris-HCl being most suit able. The assembled electrode system is stable for about 120 hours. A linear response toward potassium has been found in the range from 2.5 X 10(-3) to 1.3 X 10(-1) mol L-1. Effect of pH, temperature, and possi bly interfering substances are reported.