COMPUTER-CONTROLLED BIPOLAR PULSE CONDUCTIVITY SYSTEM FOR APPLICATIONS IN CHEMICAL RATE DETERMINATIONS

A computer-controlled bipolar pulse conductivity system has been developed for use as a detector in chemical rate determinations. The instrument has a wide dynamic range (10-1-10-8Ώ 1), and It exhibits signal-to-noise ratios of up to 6 X 103 for a single data acquisition and 6 X 105 for ensemble averages of 2000 acquisitions. The accuracy of the system depends on several instrumental factors and ranges from 1 % to 0.005 % without calibration. With calibration against suitable standards, the worst-case error is 0.02%. The system is capable of performing discrete conductance measurements in 30 µs when operating at its maximum data rate. The speed and utility of the instrument are demonstrated by its use as the detection system in stopped-flow studies of the dehydration of carbonic acid and the reaction of nitromethane with base. Numerical correction of the data for temperature changes which occur in the conductance cell is also illustrated. © 1978, American Chemical Society. All rights reserved.