Penicillin activity in brain tissue: a method for continuous measurement.

A double-barrelled microelectrode is described which permits the continuous and simultaneous measurement of penicillin concentration and of the local bioelectric activity in nervous tissue. The electrode, which is based on a chloride ligand (Corning no. 477315), has a short response time and enables reproducible measurements of penicillin concentration even below 500 IU/ml.