Rapid-sweep electrochemical detector for chemical analysis of flow streams
First Claim
1. A data acquisition system comprising computer means and a measuring and control instrument, said instrument including analog circuit means for measuring at least one variable analog function with high sensitivity, an internal data bus, digital-to-analog converter means connected to said analog circuit means and fed by said internal data bus for changing the condition of said analog circuit means in accord with digital input to said digital-to-analog converter means, analog-to-digital converter means connected to said analog circuit means for converting the variable analog function being measured to digital format, an active data bus connected with said analog-to-digital converter means for periodically acquiring data therefrom corresponding to the measured analog function, and means interfaced between said active data bus and said internal data bus for sequentially applying digital input from said computer means to said digital-to-analog converter means and for grounding the internal bus to allow the analog function to be measured without being degraded by digital noise.
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Abstract
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 (potential, time and current) 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.
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17 Claims
- 1. A data acquisition system comprising computer means and a measuring and control instrument, said instrument including analog circuit means for measuring at least one variable analog function with high sensitivity, an internal data bus, digital-to-analog converter means connected to said analog circuit means and fed by said internal data bus for changing the condition of said analog circuit means in accord with digital input to said digital-to-analog converter means, analog-to-digital converter means connected to said analog circuit means for converting the variable analog function being measured to digital format, an active data bus connected with said analog-to-digital converter means for periodically acquiring data therefrom corresponding to the measured analog function, and means interfaced between said active data bus and said internal data bus for sequentially applying digital input from said computer means to said digital-to-analog converter means and for grounding the internal bus to allow the analog function to be measured without being degraded by digital noise.
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9. A data acquisition system comprising computer means and a measuring and control instrument, said instrument including analog circuit means for measuring at least one variable analog function with high sensitivity, logic means for controlling the measuring and control instrument, and an internal data bus as an input to said analog circuit means;
- an active data bus connected to said computer means;
input means for sequentially connecting said active data bus as an input to said internal data bus and for grounding said internal data bus for a time sufficient to allow measurement with high sensitivity; and
output means for repetitiously converting said variable analog function to digital format and for connecting said digital format to said active data bus. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17)
- an active data bus connected to said computer means;
Specification