a system for identification and quantification of electrochemically active compounds in a flow stream involves stepping the electrode potential in a detector rapidly through the range of interest with a square wave superimposed on a staircase signal and recording the current response as functions of step number and sweep number , i . e ., as functions of voltage and time . from the recorded data , a three - dimensional graph is structured and from which identification and quantification of the electrochemically active compounds is effected with minimum expenditure of time . the system includes a potentiostat controlled by a computer with , however , independent logic control contained in the potentiostat . provision is also made to compensate automatically for variations in resistance between the cell electrodes .