A microcomputer-based monitoring system for the determination of residual water in organic solvents using ion-selective electrodes in a novel potentiometric method, called the proton iso-concentration technique (PICT), has been developed at UMIST. In the monitor, a sample stream is bled off and mixed with a buffer solution before passing through a cell containing a pH glass electrode, a reference electrode and an automatic temperature compensation probe. The instrument is calibrated with standard solutions containing water in the same solvent. The automatic monitoring system comprises a microcomputer and slave microprocessor system, the former performing system control and data analysis, the latter controlling a number of discrete electronic devices. Results obtained on selected industrially important solvents demonstrate a satisfactory performance of PICT in continuous monitoring, showing it to be accurate, reproducible and sensitive. On-line determination of moisture in solvents is important for process control in industry.
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