A SOLID-STATE CONTROLLED-POTENTIAL DC POLAROGRAPH WITH CYCLIC SCANNING AND CALIBRATED FIRST- AND SECOND-DERIVATIVE SCALES

This instrument is a versatile, reliable polarograph incorporating desirable design features of previous ORNL DC polarographs and having additional functional features and operating conveniences. Precision scan rates (less than 0.1% relative standard deviation) from 0.1 to 10 volts/minute in a 1, 2, 3, 5 sequence are provided. Current ranges from 0.02 μA to 10 mA in a 1,2, 5 sequence are available. Efficient filtering of the current signal from the polarographic cell makes possible the use of active first- and secondderivative networks giving accurate derivative waves on precisely calibrated scales. The gain of each derivative network is changed automatically as the scan rate is changed to make the recorded derivative peak heights essentially independent of scan rate, thus eliminating the need for a range search. When the ORNL Polarographic Drop Time Controller is used with this polarograph ata drop time of 0.5 second and a scan rate of 1 volt/minute, polarograms can be recorded in approximately 30 seconds with a relative standard deviation of 0.2% at a concentration of 10-3M. © 1969, American Chemical Society. All rights reserved.